Replace direct indexing with named methods.

36 files changed, 327 insertions, 283 deletions

diff --git a/mesonbuild/ast/introspection.py b/mesonbuild/ast/introspection.py
index 1d7dd05..1197510 100644
--- a/mesonbuild/ast/introspection.py
+++ b/mesonbuild/ast/introspection.py
@@ -182,7 +182,7 @@ class IntrospectionInterpreter(AstInterpreter):
                 if self.subproject:
                     options = {}
                     for k in comp.get_options():
-                        v = copy.copy(self.coredata.optstore[k])
+                        v = copy.copy(self.coredata.optstore.get_value_object(k))
                         k = k.evolve(subproject=self.subproject)
                         options[k] = v
                     self.coredata.add_compiler_options(options, lang, for_machine, self.environment, self.subproject)
diff --git a/mesonbuild/backend/backends.py b/mesonbuild/backend/backends.py
index 740f349..c1a72f1 100644
--- a/mesonbuild/backend/backends.py
+++ b/mesonbuild/backend/backends.py
@@ -962,7 +962,7 @@ class Backend:
     def target_uses_pch(self, target: build.BuildTarget) -> bool:
         try:
             return T.cast('bool', target.get_option(OptionKey('b_pch')))
-        except KeyError:
+        except (KeyError, AttributeError):
             return False
 
     @staticmethod
diff --git a/mesonbuild/backend/ninjabackend.py b/mesonbuild/backend/ninjabackend.py
index debde7b..759ae9a 100644
--- a/mesonbuild/backend/ninjabackend.py
+++ b/mesonbuild/backend/ninjabackend.py
@@ -623,7 +623,7 @@ class NinjaBackend(backends.Backend):
             outfile.write('# Do not edit by hand.\n\n')
             outfile.write('ninja_required_version = 1.8.2\n\n')
 
-            num_pools = self.environment.coredata.optstore[OptionKey('backend_max_links')].value
+            num_pools = self.environment.coredata.optstore.get_value('backend_max_links')
             if num_pools > 0:
                 outfile.write(f'''pool link_pool
   depth = {num_pools}
@@ -657,7 +657,7 @@ class NinjaBackend(backends.Backend):
             mlog.log_timestamp("Dist generated")
             key = OptionKey('b_coverage')
             if (key in self.environment.coredata.optstore and
-                    self.environment.coredata.optstore[key].value):
+                    self.environment.coredata.optstore.get_value(key)):
                 gcovr_exe, gcovr_version, lcov_exe, lcov_version, genhtml_exe, llvm_cov_exe = environment.find_coverage_tools(self.environment.coredata)
                 mlog.debug(f'Using {gcovr_exe} ({gcovr_version}), {lcov_exe} and {llvm_cov_exe} for code coverage')
                 if gcovr_exe or (lcov_exe and genhtml_exe):
@@ -1983,7 +1983,7 @@ class NinjaBackend(backends.Backend):
                 buildtype = target.get_option(OptionKey('buildtype'))
                 crt = target.get_option(OptionKey('b_vscrt'))
                 args += rustc.get_crt_link_args(crt, buildtype)
-            except KeyError:
+            except (KeyError, AttributeError):
                 pass
 
         if mesonlib.version_compare(rustc.version, '>= 1.67.0'):
@@ -2287,7 +2287,7 @@ class NinjaBackend(backends.Backend):
         return options
 
     def generate_static_link_rules(self):
-        num_pools = self.environment.coredata.optstore[OptionKey('backend_max_links')].value
+        num_pools = self.environment.coredata.optstore.get_value('backend_max_links')
         if 'java' in self.environment.coredata.compilers.host:
             self.generate_java_link()
         for for_machine in MachineChoice:
@@ -2335,7 +2335,7 @@ class NinjaBackend(backends.Backend):
             self.add_rule(NinjaRule(rule, cmdlist, args, description, **options, extra=pool))
 
     def generate_dynamic_link_rules(self):
-        num_pools = self.environment.coredata.optstore[OptionKey('backend_max_links')].value
+        num_pools = self.environment.coredata.optstore.get_value('backend_max_links')
         for for_machine in MachineChoice:
             complist = self.environment.coredata.compilers[for_machine]
             for langname, compiler in complist.items():
@@ -3727,7 +3727,7 @@ https://gcc.gnu.org/bugzilla/show_bug.cgi?id=47485'''))
             elem.add_dep(self.generate_custom_target_clean(ctlist))
 
         if OptionKey('b_coverage') in self.environment.coredata.optstore and \
-           self.environment.coredata.optstore[OptionKey('b_coverage')].value:
+           self.environment.coredata.optstore.get_value('b_coverage'):
             self.generate_gcov_clean()
             elem.add_dep('clean-gcda')
             elem.add_dep('clean-gcno')
diff --git a/mesonbuild/backend/vs2010backend.py b/mesonbuild/backend/vs2010backend.py
index b2b8d87..793b678 100644
--- a/mesonbuild/backend/vs2010backend.py
+++ b/mesonbuild/backend/vs2010backend.py
@@ -532,7 +532,7 @@ class Vs2010Backend(backends.Backend):
         replace_if_different(sln_filename, sln_filename_tmp)
 
     def generate_projects(self, vslite_ctx: dict = None) -> T.List[Project]:
-        startup_project = self.environment.coredata.optstore[OptionKey('backend_startup_project')].value
+        startup_project = self.environment.coredata.optstore.get_value('backend_startup_project')
         projlist: T.List[Project] = []
         startup_idx = 0
         for (i, (name, target)) in enumerate(self.build.targets.items()):
diff --git a/mesonbuild/build.py b/mesonbuild/build.py
index 517845c..071dbdf 100644
--- a/mesonbuild/build.py
+++ b/mesonbuild/build.py
@@ -664,7 +664,7 @@ class Target(HoldableObject, metaclass=abc.ABCMeta):
     def get_option(self, key: 'OptionKey') -> T.Union[str, int, bool]:
         # TODO: if it's possible to annotate get_option or validate_option_value
         # in the future we might be able to remove the cast here
-        return T.cast('T.Union[str, int, bool]', self.options[key].value)
+        return T.cast('T.Union[str, int, bool]', self.options.get_value(key))
 
     @staticmethod
     def parse_overrides(kwargs: T.Dict[str, T.Any]) -> T.Dict[OptionKey, str]:
@@ -1243,7 +1243,7 @@ class BuildTarget(Target):
         if kwargs.get(arg) is not None:
             val = T.cast('bool', kwargs[arg])
         elif k in self.environment.coredata.optstore:
-            val = self.environment.coredata.optstore[k].value
+            val = self.environment.coredata.optstore.get_value(k)
         else:
             val = False
 
@@ -1931,7 +1931,7 @@ class Executable(BuildTarget):
             kwargs):
         key = OptionKey('b_pie')
         if 'pie' not in kwargs and key in environment.coredata.optstore:
-            kwargs['pie'] = environment.coredata.optstore[key].value
+            kwargs['pie'] = environment.coredata.optstore.get_value(key)
         super().__init__(name, subdir, subproject, for_machine, sources, structured_sources, objects,
                          environment, compilers, kwargs)
         self.win_subsystem = kwargs.get('win_subsystem') or 'console'
diff --git a/mesonbuild/cmake/common.py b/mesonbuild/cmake/common.py
index 0264819..ad4ec6b 100644
--- a/mesonbuild/cmake/common.py
+++ b/mesonbuild/cmake/common.py
@@ -53,7 +53,7 @@ blacklist_cmake_defs = [
 def cmake_is_debug(env: 'Environment') -> bool:
     if OptionKey('b_vscrt') in env.coredata.optstore:
         is_debug = env.coredata.get_option(OptionKey('buildtype')) == 'debug'
-        if env.coredata.optstore[OptionKey('b_vscrt')].value in {'mdd', 'mtd'}:
+        if env.coredata.optstore.get_value('b_vscrt') in {'mdd', 'mtd'}:
             is_debug = True
         return is_debug
     else:
diff --git a/mesonbuild/cmake/executor.py b/mesonbuild/cmake/executor.py
index a8850d6..392063d 100644
--- a/mesonbuild/cmake/executor.py
+++ b/mesonbuild/cmake/executor.py
@@ -51,7 +51,7 @@ class CMakeExecutor:
             self.cmakebin = None
             return
 
-        self.prefix_paths = self.environment.coredata.optstore[OptionKey('cmake_prefix_path', machine=self.for_machine)].value
+        self.prefix_paths = self.environment.coredata.optstore.get_value(OptionKey('cmake_prefix_path', machine=self.for_machine))
         if self.prefix_paths:
             self.extra_cmake_args += ['-DCMAKE_PREFIX_PATH={}'.format(';'.join(self.prefix_paths))]
 
diff --git a/mesonbuild/cmake/interpreter.py b/mesonbuild/cmake/interpreter.py
index 57354d3..f67591f 100644
--- a/mesonbuild/cmake/interpreter.py
+++ b/mesonbuild/cmake/interpreter.py
@@ -532,7 +532,7 @@ class ConverterTarget:
     @lru_cache(maxsize=None)
     def _all_lang_stds(self, lang: str) -> 'ImmutableListProtocol[str]':
         try:
-            res = self.env.coredata.optstore[OptionKey('std', machine=MachineChoice.BUILD, lang=lang)].choices
+            res = self.env.coredata.optstore.get_value_object(OptionKey('std', machine=MachineChoice.BUILD, lang=lang)).choices
         except KeyError:
             return []
 
diff --git a/mesonbuild/compilers/c.py b/mesonbuild/compilers/c.py
index 7f2efc9..f4f1937 100644
--- a/mesonbuild/compilers/c.py
+++ b/mesonbuild/compilers/c.py
@@ -165,16 +165,16 @@ class ClangCCompiler(_ClangCStds, ClangCompiler, CCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
-            args.append('-std=' + std.value)
+        std = options.get_value(key)
+        if std != 'none':
+            args.append('-std=' + std)
         return args
 
     def get_option_link_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         if self.info.is_windows() or self.info.is_cygwin():
             # without a typedict mypy can't understand this.
             key = self.form_langopt_key('winlibs')
-            libs = options[key].value.copy()
+            libs = options.get_value(key).copy()
             assert isinstance(libs, list)
             for l in libs:
                 assert isinstance(l, str)
@@ -258,9 +258,9 @@ class ArmclangCCompiler(ArmclangCompiler, CCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
-            args.append('-std=' + std.value)
+        std = options.get_value(key)
+        if std != 'none':
+            args.append('-std=' + std)
         return args
 
     def get_option_link_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
@@ -318,16 +318,16 @@ class GnuCCompiler(GnuCompiler, CCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
-            args.append('-std=' + std.value)
+        std = options.get_value(key)
+        if std != 'none':
+            args.append('-std=' + std)
         return args
 
     def get_option_link_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         if self.info.is_windows() or self.info.is_cygwin():
             # without a typeddict mypy can't figure this out
             key = self.form_langopt_key('winlibs')
-            libs: T.List[str] = options[key].value.copy()
+            libs: T.List[str] = options.get_value(key).copy()
             assert isinstance(libs, list)
             for l in libs:
                 assert isinstance(l, str)
@@ -432,9 +432,9 @@ class IntelCCompiler(IntelGnuLikeCompiler, CCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
-            args.append('-std=' + std.value)
+        std = options.get_value(key)
+        if std != 'none':
+            args.append('-std=' + std)
         return args
 
 
@@ -461,7 +461,7 @@ class VisualStudioLikeCCompilerMixin(CompilerMixinBase):
     def get_option_link_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         # need a TypeDict to make this work
         key = self.form_langopt_key('winlibs')
-        libs = options[key].value.copy()
+        libs = options.get_value(key).copy()
         assert isinstance(libs, list)
         for l in libs:
             assert isinstance(l, str)
@@ -498,11 +498,11 @@ class VisualStudioCCompiler(MSVCCompiler, VisualStudioLikeCCompilerMixin, CCompi
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args = []
         key = self.form_langopt_key('std')
-        std = options[key]
+        std = options.get_value(key)
         # As of MVSC 16.8, /std:c11 and /std:c17 are the only valid C standard options.
-        if std.value in {'c11'}:
+        if std == 'c11':
             args.append('/std:c11')
-        elif std.value in {'c17', 'c18'}:
+        elif std in {'c17', 'c18'}:
             args.append('/std:c17')
         return args
 
@@ -519,7 +519,7 @@ class ClangClCCompiler(_ClangCStds, ClangClCompiler, VisualStudioLikeCCompilerMi
 
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         key = self.form_langopt_key('std')
-        std = options[key].value
+        std = options.get_value(key)
         if std != "none":
             return [f'/clang:-std={std}']
         return []
@@ -541,7 +541,7 @@ class IntelClCCompiler(IntelVisualStudioLikeCompiler, VisualStudioLikeCCompilerM
     def get_options(self) -> 'MutableKeyedOptionDictType':
         opts = super().get_options()
         key = self.form_langopt_key('std')
-        std_opt = opts[key]
+        std_opt = opts.get_value_object(key)
         assert isinstance(std_opt, options.UserStdOption), 'for mypy'
         std_opt.set_versions(['c89', 'c99', 'c11'])
         return opts
@@ -549,11 +549,11 @@ class IntelClCCompiler(IntelVisualStudioLikeCompiler, VisualStudioLikeCCompilerM
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value == 'c89':
+        std = options.get_value(key)
+        if std == 'c89':
             mlog.log("ICL doesn't explicitly implement c89, setting the standard to 'none', which is close.", once=True)
-        elif std.value != 'none':
-            args.append('/Qstd:' + std.value)
+        elif std != 'none':
+            args.append('/Qstd:' + std)
         return args
 
 
@@ -583,9 +583,9 @@ class ArmCCompiler(ArmCompiler, CCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
-            args.append('--' + std.value)
+        std = options.get_value(key)
+        if std != 'none':
+            args.append('--' + std)
         return args
 
 
@@ -616,10 +616,10 @@ class CcrxCCompiler(CcrxCompiler, CCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value == 'c89':
+        std = options.get_value(key)
+        if std == 'c89':
             args.append('-lang=c')
-        elif std.value == 'c99':
+        elif std == 'c99':
             args.append('-lang=c99')
         return args
 
@@ -664,10 +664,10 @@ class Xc16CCompiler(Xc16Compiler, CCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
+        std = options.get_value(key)
+        if std != 'none':
             args.append('-ansi')
-            args.append('-std=' + std.value)
+            args.append('-std=' + std)
         return args
 
     def get_compile_only_args(self) -> T.List[str]:
@@ -748,9 +748,9 @@ class TICCompiler(TICompiler, CCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
-            args.append('--' + std.value)
+        std = options.get_value(key)
+        if std != 'none':
+            args.append('--' + std)
         return args
 
 class C2000CCompiler(TICCompiler):
@@ -784,10 +784,10 @@ class MetrowerksCCompilerARM(MetrowerksCompiler, CCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
+        std = options.get_value(key)
+        if std != 'none':
             args.append('-lang')
-            args.append(std.value)
+            args.append(std)
         return args
 
 class MetrowerksCCompilerEmbeddedPowerPC(MetrowerksCompiler, CCompiler):
@@ -814,7 +814,7 @@ class MetrowerksCCompilerEmbeddedPowerPC(MetrowerksCompiler, CCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
-            args.append('-lang ' + std.value)
+        std = options.get_value(key)
+        if std != 'none':
+            args.append('-lang ' + std)
         return args
diff --git a/mesonbuild/compilers/compilers.py b/mesonbuild/compilers/compilers.py
index ef0ea70..1e386bb 100644
--- a/mesonbuild/compilers/compilers.py
+++ b/mesonbuild/compilers/compilers.py
@@ -254,7 +254,7 @@ def option_enabled(boptions: T.Set[OptionKey], options: 'KeyedOptionDictType',
     try:
         if option not in boptions:
             return False
-        ret = options[option].value
+        ret = options.get_value(option)
         assert isinstance(ret, bool), 'must return bool'  # could also be str
         return ret
     except KeyError:
@@ -264,8 +264,8 @@ def option_enabled(boptions: T.Set[OptionKey], options: 'KeyedOptionDictType',
 def get_option_value(options: 'KeyedOptionDictType', opt: OptionKey, fallback: '_T') -> '_T':
     """Get the value of an option, or the fallback value."""
     try:
-        v: '_T' = options[opt].value
-    except KeyError:
+        v: '_T' = options.get_value(opt)
+    except (KeyError, AttributeError):
         return fallback
 
     assert isinstance(v, type(fallback)), f'Should have {type(fallback)!r} but was {type(v)!r}'
@@ -279,52 +279,52 @@ def are_asserts_disabled(options: KeyedOptionDictType) -> bool:
     :param options: OptionDictionary
     :return: whether to disable assertions or not
     """
-    return (options[OptionKey('b_ndebug')].value == 'true' or
-            (options[OptionKey('b_ndebug')].value == 'if-release' and
-             options[OptionKey('buildtype')].value in {'release', 'plain'}))
+    return (options.get_value('b_ndebug') == 'true' or
+            (options.get_value('b_ndebug') == 'if-release' and
+             options.get_value('buildtype') in {'release', 'plain'}))
 
 
 def get_base_compile_args(options: 'KeyedOptionDictType', compiler: 'Compiler', env: 'Environment') -> T.List[str]:
     args: T.List[str] = []
     try:
-        if options[OptionKey('b_lto')].value:
+        if options.get_value(OptionKey('b_lto')):
             args.extend(compiler.get_lto_compile_args(
                 threads=get_option_value(options, OptionKey('b_lto_threads'), 0),
                 mode=get_option_value(options, OptionKey('b_lto_mode'), 'default')))
-    except KeyError:
+    except (KeyError, AttributeError):
         pass
     try:
-        args += compiler.get_colorout_args(options[OptionKey('b_colorout')].value)
-    except KeyError:
+        args += compiler.get_colorout_args(options.get_value(OptionKey('b_colorout')))
+    except (KeyError, AttributeError):
         pass
     try:
-        args += compiler.sanitizer_compile_args(options[OptionKey('b_sanitize')].value)
-    except KeyError:
+        args += compiler.sanitizer_compile_args(options.get_value(OptionKey('b_sanitize')))
+    except (KeyError, AttributeError):
         pass
     try:
-        pgo_val = options[OptionKey('b_pgo')].value
+        pgo_val = options.get_value(OptionKey('b_pgo'))
         if pgo_val == 'generate':
             args.extend(compiler.get_profile_generate_args())
         elif pgo_val == 'use':
             args.extend(compiler.get_profile_use_args())
-    except KeyError:
+    except (KeyError, AttributeError):
         pass
     try:
-        if options[OptionKey('b_coverage')].value:
+        if options.get_value(OptionKey('b_coverage')):
             args += compiler.get_coverage_args()
-    except KeyError:
+    except (KeyError, AttributeError):
         pass
     try:
         args += compiler.get_assert_args(are_asserts_disabled(options), env)
-    except KeyError:
+    except (KeyError, AttributeError):
         pass
     # This does not need a try...except
     if option_enabled(compiler.base_options, options, OptionKey('b_bitcode')):
         args.append('-fembed-bitcode')
     try:
-        crt_val = options[OptionKey('b_vscrt')].value
-        buildtype = options[OptionKey('buildtype')].value
         try:
+            crt_val = options.get_value(OptionKey('b_vscrt'))
+            buildtype = options.get_value(OptionKey('buildtype'))
             args += compiler.get_crt_compile_args(crt_val, buildtype)
         except AttributeError:
             pass
@@ -336,8 +336,8 @@ def get_base_link_args(options: 'KeyedOptionDictType', linker: 'Compiler',
                        is_shared_module: bool, build_dir: str) -> T.List[str]:
     args: T.List[str] = []
     try:
-        if options[OptionKey('b_lto')].value:
-            if options[OptionKey('werror')].value:
+        if options.get_value('b_lto'):
+            if options.get_value('werror'):
                 args.extend(linker.get_werror_args())
 
             thinlto_cache_dir = None
@@ -349,24 +349,24 @@ def get_base_link_args(options: 'KeyedOptionDictType', linker: 'Compiler',
                 threads=get_option_value(options, OptionKey('b_lto_threads'), 0),
                 mode=get_option_value(options, OptionKey('b_lto_mode'), 'default'),
                 thinlto_cache_dir=thinlto_cache_dir))
-    except KeyError:
+    except (KeyError, AttributeError):
         pass
     try:
-        args += linker.sanitizer_link_args(options[OptionKey('b_sanitize')].value)
-    except KeyError:
+        args += linker.sanitizer_link_args(options.get_value('b_sanitize'))
+    except (KeyError, AttributeError):
         pass
     try:
-        pgo_val = options[OptionKey('b_pgo')].value
+        pgo_val = options.get_value('b_pgo')
         if pgo_val == 'generate':
             args.extend(linker.get_profile_generate_args())
         elif pgo_val == 'use':
             args.extend(linker.get_profile_use_args())
-    except KeyError:
+    except (KeyError, AttributeError):
         pass
     try:
-        if options[OptionKey('b_coverage')].value:
+        if options.get_value('b_coverage'):
             args += linker.get_coverage_link_args()
-    except KeyError:
+    except (KeyError, AttributeError):
         pass
 
     as_needed = option_enabled(linker.base_options, options, OptionKey('b_asneeded'))
@@ -390,9 +390,9 @@ def get_base_link_args(options: 'KeyedOptionDictType', linker: 'Compiler',
             args.extend(linker.get_allow_undefined_link_args())
 
     try:
-        crt_val = options[OptionKey('b_vscrt')].value
-        buildtype = options[OptionKey('buildtype')].value
         try:
+            crt_val = options.get_value(OptionKey('b_vscrt'))
+            buildtype = options.get_value(OptionKey('buildtype'))
             args += linker.get_crt_link_args(crt_val, buildtype)
         except AttributeError:
             pass
diff --git a/mesonbuild/compilers/cpp.py b/mesonbuild/compilers/cpp.py
index 12d7201..a01b377 100644
--- a/mesonbuild/compilers/cpp.py
+++ b/mesonbuild/compilers/cpp.py
@@ -278,15 +278,15 @@ class ClangCPPCompiler(_StdCPPLibMixin, ClangCompiler, CPPCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args: T.List[str] = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
-            args.append(self._find_best_cpp_std(std.value))
+        std = options.get_value(key)
+        if std != 'none':
+            args.append(self._find_best_cpp_std(std))
 
         key = self.form_langopt_key('eh')
-        non_msvc_eh_options(options[key].value, args)
+        non_msvc_eh_options(options.get_value(key), args)
 
         key = self.form_langopt_key('debugstl')
-        if options[key].value:
+        if options.get_value(key):
             args.append('-D_GLIBCXX_DEBUG=1')
 
             # We can't do _LIBCPP_DEBUG because it's unreliable unless libc++ was built with it too:
@@ -296,7 +296,7 @@ class ClangCPPCompiler(_StdCPPLibMixin, ClangCompiler, CPPCompiler):
                 args.append('-D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_DEBUG')
 
         key = self.form_langopt_key('rtti')
-        if not options[key].value:
+        if not options.get_value(key):
             args.append('-fno-rtti')
 
         return args
@@ -305,7 +305,7 @@ class ClangCPPCompiler(_StdCPPLibMixin, ClangCompiler, CPPCompiler):
         if self.info.is_windows() or self.info.is_cygwin():
             # without a typedict mypy can't understand this.
             key = self.form_langopt_key('winlibs')
-            libs = options[key].value.copy()
+            libs = options.get_value(key).copy()
             assert isinstance(libs, list)
             for l in libs:
                 assert isinstance(l, str)
@@ -365,9 +365,9 @@ class EmscriptenCPPCompiler(EmscriptenMixin, ClangCPPCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args: T.List[str] = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
-            args.append(self._find_best_cpp_std(std.value))
+        std = options.get_value(key)
+        if std != 'none':
+            args.append(self._find_best_cpp_std(std))
         return args
 
 
@@ -409,12 +409,12 @@ class ArmclangCPPCompiler(ArmclangCompiler, CPPCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args: T.List[str] = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
-            args.append('-std=' + std.value)
+        std = options.get_value(key)
+        if std != 'none':
+            args.append('-std=' + std)
 
         key = self.form_langopt_key('eh')
-        non_msvc_eh_options(options[key].value, args)
+        non_msvc_eh_options(options.get_value(key), args)
 
         return args
 
@@ -483,16 +483,16 @@ class GnuCPPCompiler(_StdCPPLibMixin, GnuCompiler, CPPCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args: T.List[str] = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
-            args.append(self._find_best_cpp_std(std.value))
+        std = options.get_value(key)
+        if std != 'none':
+            args.append(self._find_best_cpp_std(std))
 
-        non_msvc_eh_options(options[key.evolve('eh')].value, args)
+        non_msvc_eh_options(options.get_value(key.evolve('eh')), args)
 
-        if not options[key.evolve('rtti')].value:
+        if not options.get_value(key.evolve('rtti')):
             args.append('-fno-rtti')
 
-        if options[key.evolve('debugstl')].value:
+        if options.get_value(key.evolve('debugstl')):
             args.append('-D_GLIBCXX_DEBUG=1')
         return args
 
@@ -500,7 +500,7 @@ class GnuCPPCompiler(_StdCPPLibMixin, GnuCompiler, CPPCompiler):
         if self.info.is_windows() or self.info.is_cygwin():
             # without a typedict mypy can't understand this.
             key = self.form_langopt_key('winlibs')
-            libs = options[key].value.copy()
+            libs = options.get_value(key).copy()
             assert isinstance(libs, list)
             for l in libs:
                 assert isinstance(l, str)
@@ -616,15 +616,15 @@ class ElbrusCPPCompiler(ElbrusCompiler, CPPCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args: T.List[str] = []
         key = self.form_langopt_key('std')
-        std = options[key]
+        std = options.get_value(key)
         if std.value != 'none':
             args.append(self._find_best_cpp_std(std.value))
 
         key = self.form_langopt_key('eh')
-        non_msvc_eh_options(options[key].value, args)
+        non_msvc_eh_options(options.get_value(key), args)
 
         key = self.form_langopt_key('debugstl')
-        if options[key].value:
+        if options.get_value(key):
             args.append('-D_GLIBCXX_DEBUG=1')
         return args
 
@@ -688,18 +688,18 @@ class IntelCPPCompiler(IntelGnuLikeCompiler, CPPCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args: T.List[str] = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
+        std = options.get_value(key)
+        if std != 'none':
             remap_cpp03 = {
                 'c++03': 'c++98',
                 'gnu++03': 'gnu++98'
             }
-            args.append('-std=' + remap_cpp03.get(std.value, std.value))
-        if options[key.evolve('eh')].value == 'none':
+            args.append('-std=' + remap_cpp03.get(std.value, std))
+        if options.get_value(key.evolve('eh')) == 'none':
             args.append('-fno-exceptions')
-        if not options[key.evolve('rtti')].value:
+        if not options.get_value(key.evolve('rtti')):
             args.append('-fno-rtti')
-        if options[key.evolve('debugstl')].value:
+        if options.get_value(key.evolve('debugstl')):
             args.append('-D_GLIBCXX_DEBUG=1')
         return args
 
@@ -733,7 +733,7 @@ class VisualStudioLikeCPPCompilerMixin(CompilerMixinBase):
     def get_option_link_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         # need a typeddict for this
         key = self.form_langopt_key('winlibs')
-        return T.cast('T.List[str]', options[key].value[:])
+        return T.cast('T.List[str]', options.get_value(key)[:])
 
     def _get_options_impl(self, opts: 'MutableKeyedOptionDictType', cpp_stds: T.List[str]) -> 'MutableKeyedOptionDictType':
         key = self.form_langopt_key('std')
@@ -762,18 +762,18 @@ class VisualStudioLikeCPPCompilerMixin(CompilerMixinBase):
         args: T.List[str] = []
         key = self.form_langopt_key('std')
 
-        eh = options[self.form_langopt_key('eh')]
-        if eh.value == 'default':
+        eh = options.get_value(self.form_langopt_key('eh'))
+        if eh == 'default':
             args.append('/EHsc')
-        elif eh.value == 'none':
+        elif eh == 'none':
             args.append('/EHs-c-')
         else:
-            args.append('/EH' + eh.value)
+            args.append('/EH' + eh)
 
-        if not options[self.form_langopt_key('rtti')].value:
+        if not options.get_value(self.form_langopt_key('rtti')):
             args.append('/GR-')
 
-        permissive, ver = self.VC_VERSION_MAP[options[key].value]
+        permissive, ver = self.VC_VERSION_MAP[options.get_value(key)]
 
         if ver is not None:
             args.append(f'/std:c++{ver}')
@@ -801,7 +801,7 @@ class CPP11AsCPP14Mixin(CompilerMixinBase):
         # (i.e., after VS2015U3)
         # if one is using anything before that point, one cannot set the standard.
         key = self.form_langopt_key('std')
-        if options[key].value in {'vc++11', 'c++11'}:
+        if options.get_value(key) in {'vc++11', 'c++11'}:
             mlog.warning(self.id, 'does not support C++11;',
                          'attempting best effort; setting the standard to C++14',
                          once=True, fatal=False)
@@ -809,10 +809,10 @@ class CPP11AsCPP14Mixin(CompilerMixinBase):
             # deepcopy since we're messing with members, and we can't simply
             # copy the members because the option proxy doesn't support it.
             options = copy.deepcopy(options)
-            if options[key].value == 'vc++11':
-                options[key].value = 'vc++14'
+            if options.get_value(key) == 'vc++11':
+                options.set_value(key,'vc++14')
             else:
-                options[key].value = 'c++14'
+                options.set_value(key,  'c++14')
         return super().get_option_compile_args(options)
 
 
@@ -848,10 +848,10 @@ class VisualStudioCPPCompiler(CPP11AsCPP14Mixin, VisualStudioLikeCPPCompilerMixi
 
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         key = self.form_langopt_key('std')
-        if options[key].value != 'none' and version_compare(self.version, '<19.00.24210'):
+        if options.get_value(key) != 'none' and version_compare(self.version, '<19.00.24210'):
             mlog.warning('This version of MSVC does not support cpp_std arguments', fatal=False)
             options = copy.copy(options)
-            options[key].value = 'none'
+            options.set_value(key, 'none')
 
         args = super().get_option_compile_args(options)
 
@@ -924,10 +924,10 @@ class ArmCPPCompiler(ArmCompiler, CPPCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args: T.List[str] = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value == 'c++11':
+        std = options.get_value(key)
+        if std == 'c++11':
             args.append('--cpp11')
-        elif std.value == 'c++03':
+        elif std == 'c++03':
             args.append('--cpp')
         return args
 
@@ -986,9 +986,9 @@ class TICPPCompiler(TICompiler, CPPCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args: T.List[str] = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
-            args.append('--' + std.value)
+        std = options.get_value(key)
+        if std != 'none':
+            args.append('--' + std)
         return args
 
     def get_always_args(self) -> T.List[str]:
@@ -1027,10 +1027,10 @@ class MetrowerksCPPCompilerARM(MetrowerksCompiler, CPPCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args: T.List[str] = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
+        std = options.get_value(key)
+        if std != 'none':
             args.append('-lang')
-            args.append(std.value)
+            args.append(std)
         return args
 
 class MetrowerksCPPCompilerEmbeddedPowerPC(MetrowerksCompiler, CPPCompiler):
@@ -1056,7 +1056,7 @@ class MetrowerksCPPCompilerEmbeddedPowerPC(MetrowerksCompiler, CPPCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args: T.List[str] = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
-            args.append('-lang ' + std.value)
+        std = options.get_value(key)
+        if std != 'none':
+            args.append('-lang ' + std)
         return args
diff --git a/mesonbuild/compilers/cuda.py b/mesonbuild/compilers/cuda.py
index 5a93551..2e9218e 100644
--- a/mesonbuild/compilers/cuda.py
+++ b/mesonbuild/compilers/cuda.py
@@ -13,7 +13,7 @@ from .. import options
 from .. import mlog
 from ..mesonlib import (
     EnvironmentException, Popen_safe,
-    is_windows, LibType, version_compare,
+    is_windows, LibType, version_compare, OptionKey
 )
 from .compilers import Compiler
 
@@ -655,15 +655,15 @@ class CudaCompiler(Compiler):
                                ''),
         )
 
-    def _to_host_compiler_options(self, options: 'KeyedOptionDictType') -> 'KeyedOptionDictType':
+    def _to_host_compiler_options(self, master_options: 'KeyedOptionDictType') -> 'KeyedOptionDictType':
         """
         Convert an NVCC Option set to a host compiler's option set.
         """
 
         # We must strip the -std option from the host compiler option set, as NVCC has
         # its own -std flag that may not agree with the host compiler's.
-        host_options = {key: options.get(key, opt) for key, opt in self.host_compiler.get_options().items()}
-        std_key = self.form_langopt_key('std')
+        host_options = {key: master_options.get(key, opt) for key, opt in self.host_compiler.get_options().items()}
+        std_key = OptionKey('std', machine=self.for_machine, lang=self.host_compiler.language)
         overrides = {std_key: 'none'}
         return coredata.OptionsView(host_options, overrides=overrides)
 
@@ -674,9 +674,9 @@ class CudaCompiler(Compiler):
         # and attempting to use it will result in a warning: https://stackoverflow.com/a/51272091/741027
         if not is_windows():
             key = self.form_langopt_key('std')
-            std = options[key]
-            if std.value != 'none':
-                args.append('--std=' + std.value)
+            std = options.get_value(key)
+            if std != 'none':
+                args.append('--std=' + std)
 
         return args + self._to_host_flags(self.host_compiler.get_option_compile_args(self._to_host_compiler_options(options)))
 
@@ -792,9 +792,9 @@ class CudaCompiler(Compiler):
     def get_dependency_link_args(self, dep: 'Dependency') -> T.List[str]:
         return self._to_host_flags(super().get_dependency_link_args(dep), _Phase.LINKER)
 
-    def get_ccbin_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
+    def get_ccbin_args(self, ccoptions: 'KeyedOptionDictType') -> T.List[str]:
         key = self.form_langopt_key('ccbindir')
-        ccbindir = options[key].value
+        ccbindir = ccoptions.get_value(key)
         if isinstance(ccbindir, str) and ccbindir != '':
             return [self._shield_nvcc_list_arg('-ccbin='+ccbindir, False)]
         else:
diff --git a/mesonbuild/compilers/cython.py b/mesonbuild/compilers/cython.py
index 76e66c0..7c11286 100644
--- a/mesonbuild/compilers/cython.py
+++ b/mesonbuild/compilers/cython.py
@@ -84,10 +84,10 @@ class CythonCompiler(Compiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args: T.List[str] = []
         key = self.form_langopt_key('version')
-        version = options[key]
-        args.append(f'-{version.value}')
+        version = options.get_value(key)
+        args.append(f'-{version}')
         key = self.form_langopt_key('language')
-        lang = options[key]
-        if lang.value == 'cpp':
+        lang = options.get_value(key)
+        if lang == 'cpp':
             args.append('--cplus')
         return args
diff --git a/mesonbuild/compilers/fortran.py b/mesonbuild/compilers/fortran.py
index 66fb466..9b288e9 100644
--- a/mesonbuild/compilers/fortran.py
+++ b/mesonbuild/compilers/fortran.py
@@ -154,9 +154,9 @@ class GnuFortranCompiler(GnuCompiler, FortranCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args: T.List[str] = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
-            args.append('-std=' + std.value)
+        std = options.get_value(key)
+        if std != 'none':
+            args.append('-std=' + std)
         return args
 
     def get_dependency_gen_args(self, outtarget: str, outfile: str) -> T.List[str]:
@@ -291,10 +291,10 @@ class IntelFortranCompiler(IntelGnuLikeCompiler, FortranCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args: T.List[str] = []
         key = self.form_langopt_key('std')
-        std = options[key]
+        std = options.get_value(key)
         stds = {'legacy': 'none', 'f95': 'f95', 'f2003': 'f03', 'f2008': 'f08', 'f2018': 'f18'}
-        if std.value != 'none':
-            args.append('-stand=' + stds[std.value])
+        if std != 'none':
+            args.append('-stand=' + stds[std])
         return args
 
     def get_preprocess_only_args(self) -> T.List[str]:
@@ -346,10 +346,10 @@ class IntelClFortranCompiler(IntelVisualStudioLikeCompiler, FortranCompiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args: T.List[str] = []
         key = self.form_langopt_key('std')
-        std = options[key]
+        std = options.get_value(key)
         stds = {'legacy': 'none', 'f95': 'f95', 'f2003': 'f03', 'f2008': 'f08', 'f2018': 'f18'}
-        if std.value != 'none':
-            args.append('/stand:' + stds[std.value])
+        if std != 'none':
+            args.append('/stand:' + stds[std])
         return args
 
     def get_werror_args(self) -> T.List[str]:
diff --git a/mesonbuild/compilers/mixins/clike.py b/mesonbuild/compilers/mixins/clike.py
index 87cb819..70e81a4 100644
--- a/mesonbuild/compilers/mixins/clike.py
+++ b/mesonbuild/compilers/mixins/clike.py
@@ -26,7 +26,7 @@ from ... import arglist
 from ... import mesonlib
 from ... import mlog
 from ...linkers.linkers import GnuLikeDynamicLinkerMixin, SolarisDynamicLinker, CompCertDynamicLinker
-from ...mesonlib import LibType, OptionKey
+from ...mesonlib import LibType
 from .. import compilers
 from ..compilers import CompileCheckMode
 from .visualstudio import VisualStudioLikeCompiler
@@ -376,8 +376,8 @@ class CLikeCompiler(Compiler):
             # linking with static libraries since MSVC won't select a CRT for
             # us in that case and will error out asking us to pick one.
             try:
-                crt_val = env.coredata.optstore[OptionKey('b_vscrt')].value
-                buildtype = env.coredata.optstore[OptionKey('buildtype')].value
+                crt_val = env.coredata.optstore.get_value('b_vscrt')
+                buildtype = env.coredata.optstore.get_value('buildtype')
                 cargs += self.get_crt_compile_args(crt_val, buildtype)
             except (KeyError, AttributeError):
                 pass
diff --git a/mesonbuild/compilers/mixins/emscripten.py b/mesonbuild/compilers/mixins/emscripten.py
index 8d3dc95..6b7f087 100644
--- a/mesonbuild/compilers/mixins/emscripten.py
+++ b/mesonbuild/compilers/mixins/emscripten.py
@@ -51,7 +51,7 @@ class EmscriptenMixin(Compiler):
 
     def thread_link_flags(self, env: 'Environment') -> T.List[str]:
         args = ['-pthread']
-        count: int = env.coredata.optstore[OptionKey('thread_count', lang=self.language, machine=self.for_machine)].value
+        count: int = env.coredata.optstore.get_value(OptionKey('thread_count', lang=self.language, machine=self.for_machine))
         if count:
             args.append(f'-sPTHREAD_POOL_SIZE={count}')
         return args
diff --git a/mesonbuild/compilers/objc.py b/mesonbuild/compilers/objc.py
index 4d33ec8..c63f288 100644
--- a/mesonbuild/compilers/objc.py
+++ b/mesonbuild/compilers/objc.py
@@ -90,9 +90,9 @@ class ClangObjCCompiler(ClangCompiler, ObjCCompiler):
 
     def get_option_compile_args(self, options: 'coredata.KeyedOptionDictType') -> T.List[str]:
         args = []
-        std = options[OptionKey('std', machine=self.for_machine, lang='c')]
-        if std.value != 'none':
-            args.append('-std=' + std.value)
+        std = options.get_value(OptionKey('std', machine=self.for_machine, lang='c'))
+        if std != 'none':
+            args.append('-std=' + std)
         return args
 
 class AppleClangObjCCompiler(ClangObjCCompiler):
diff --git a/mesonbuild/compilers/objcpp.py b/mesonbuild/compilers/objcpp.py
index e28e3ed..e24406c 100644
--- a/mesonbuild/compilers/objcpp.py
+++ b/mesonbuild/compilers/objcpp.py
@@ -92,9 +92,9 @@ class ClangObjCPPCompiler(ClangCompiler, ObjCPPCompiler):
 
     def get_option_compile_args(self, options: 'coredata.KeyedOptionDictType') -> T.List[str]:
         args = []
-        std = options[OptionKey('std', machine=self.for_machine, lang='cpp')]
-        if std.value != 'none':
-            args.append('-std=' + std.value)
+        std = options.get_value(OptionKey('std', machine=self.for_machine, lang='cpp'))
+        if std != 'none':
+            args.append('-std=' + std)
         return args
 
 
diff --git a/mesonbuild/compilers/rust.py b/mesonbuild/compilers/rust.py
index 346a3dd..b130c58 100644
--- a/mesonbuild/compilers/rust.py
+++ b/mesonbuild/compilers/rust.py
@@ -173,9 +173,9 @@ class RustCompiler(Compiler):
     def get_option_compile_args(self, options: 'KeyedOptionDictType') -> T.List[str]:
         args = []
         key = self.form_langopt_key('std')
-        std = options[key]
-        if std.value != 'none':
-            args.append('--edition=' + std.value)
+        std = options.get_value(key)
+        if std != 'none':
+            args.append('--edition=' + std)
         return args
 
     def get_crt_compile_args(self, crt_val: str, buildtype: str) -> T.List[str]:
diff --git a/mesonbuild/coredata.py b/mesonbuild/coredata.py
index 8804547..60f3574 100644
--- a/mesonbuild/coredata.py
+++ b/mesonbuild/coredata.py
@@ -58,7 +58,7 @@ if T.TYPE_CHECKING:
 
     OptionDictType = T.Union[T.Dict[str, 'options.UserOption[T.Any]'], 'OptionsView']
     MutableKeyedOptionDictType = T.Dict['OptionKey', 'options.UserOption[T.Any]']
-    KeyedOptionDictType = T.Union['options.OptionStore', MutableKeyedOptionDictType, 'OptionsView']
+    KeyedOptionDictType = T.Union['options.OptionStore', 'OptionsView']
     CompilerCheckCacheKey = T.Tuple[T.Tuple[str, ...], str, FileOrString, T.Tuple[str, ...], CompileCheckMode]
     # code, args
     RunCheckCacheKey = T.Tuple[str, T.Tuple[str, ...]]
@@ -150,8 +150,8 @@ class DependencyCache:
 
     def __calculate_subkey(self, type_: DependencyCacheType) -> T.Tuple[str, ...]:
         data: T.Dict[DependencyCacheType, T.List[str]] = {
-            DependencyCacheType.PKG_CONFIG: stringlistify(self.__builtins[self.__pkg_conf_key].value),
-            DependencyCacheType.CMAKE: stringlistify(self.__builtins[self.__cmake_key].value),
+            DependencyCacheType.PKG_CONFIG: stringlistify(self.__builtins.get_value(self.__pkg_conf_key)),
+            DependencyCacheType.CMAKE: stringlistify(self.__builtins.get_value(self.__cmake_key)),
             DependencyCacheType.OTHER: [],
         }
         assert type_ in data, 'Someone forgot to update subkey calculations for a new type'
@@ -415,33 +415,33 @@ class CoreData:
             if opt.yielding:
                 # This option is global and not per-subproject
                 return
-            value = opts_map[key.as_root()].value
+            value = opts_map.get_value(key.as_root())
         else:
             value = None
-        opts_map[key] = opt.init_option(key, value, options.default_prefix())
+        opts_map.add_system_option(key, opt.init_option(key, value, options.default_prefix()))
 
     def init_backend_options(self, backend_name: str) -> None:
         if backend_name == 'ninja':
-            self.optstore[OptionKey('backend_max_links')] = options.UserIntegerOption(
+            self.optstore.add_system_option('backend_max_links', options.UserIntegerOption(
                 'backend_max_links',
                 'Maximum number of linker processes to run or 0 for no '
                 'limit',
-                (0, None, 0))
+                (0, None, 0)))
         elif backend_name.startswith('vs'):
-            self.optstore[OptionKey('backend_startup_project')] = options.UserStringOption(
+            self.optstore.add_system_option('backend_startup_project', options.UserStringOption(
                 'backend_startup_project',
                 'Default project to execute in Visual Studio',
-                '')
+                ''))
 
     def get_option(self, key: OptionKey) -> T.Union[T.List[str], str, int, bool]:
         try:
-            v = self.optstore[key].value
+            v = self.optstore.get_value(key)
             return v
         except KeyError:
             pass
 
         try:
-            v = self.optstore[key.as_root()]
+            v = self.optstore.get_value_object(key.as_root())
             if v.yielding:
                 return v.value
         except KeyError:
@@ -455,11 +455,11 @@ class CoreData:
             if key.name == 'prefix':
                 value = self.sanitize_prefix(value)
             else:
-                prefix = self.optstore[OptionKey('prefix')].value
+                prefix = self.optstore.get_value('prefix')
                 value = self.sanitize_dir_option_value(prefix, key, value)
 
         try:
-            opt = self.optstore[key]
+            opt = self.optstore.get_value_object(key)
         except KeyError:
             raise MesonException(f'Tried to set unknown builtin option {str(key)}')
 
@@ -510,7 +510,7 @@ class CoreData:
 
     def get_nondefault_buildtype_args(self) -> T.List[T.Union[T.Tuple[str, str, str], T.Tuple[str, bool, bool]]]:
         result: T.List[T.Union[T.Tuple[str, str, str], T.Tuple[str, bool, bool]]] = []
-        value = self.optstore[OptionKey('buildtype')].value
+        value = self.optstore.get_value('buildtype')
         if value == 'plain':
             opt = 'plain'
             debug = False
@@ -529,8 +529,8 @@ class CoreData:
         else:
             assert value == 'custom'
             return []
-        actual_opt = self.optstore[OptionKey('optimization')].value
-        actual_debug = self.optstore[OptionKey('debug')].value
+        actual_opt = self.optstore.get_value('optimization')
+        actual_debug = self.optstore.get_value('debug')
         if actual_opt != opt:
             result.append(('optimization', actual_opt, opt))
         if actual_debug != debug:
@@ -559,8 +559,8 @@ class CoreData:
             assert value == 'custom'
             return False
 
-        dirty |= self.optstore[OptionKey('optimization')].set_value(opt)
-        dirty |= self.optstore[OptionKey('debug')].set_value(debug)
+        dirty |= self.optstore.set_value('optimization', opt)
+        dirty |= self.optstore.set_value('debug', debug)
 
         return dirty
 
@@ -572,30 +572,32 @@ class CoreData:
 
     def get_external_args(self, for_machine: MachineChoice, lang: str) -> T.List[str]:
         # mypy cannot analyze type of OptionKey
-        return T.cast('T.List[str]', self.optstore[OptionKey('args', machine=for_machine, lang=lang)].value)
+        key = OptionKey('args', machine=for_machine, lang=lang)
+        return T.cast('T.List[str]', self.optstore.get_value(key))
 
     def get_external_link_args(self, for_machine: MachineChoice, lang: str) -> T.List[str]:
         # mypy cannot analyze type of OptionKey
-        return T.cast('T.List[str]', self.optstore[OptionKey('link_args', machine=for_machine, lang=lang)].value)
+        key = OptionKey('link_args', machine=for_machine, lang=lang)
+        return T.cast('T.List[str]', self.optstore.get_value(key))
 
-    def update_project_options(self, options: 'MutableKeyedOptionDictType', subproject: SubProject) -> None:
-        for key, value in options.items():
+    def update_project_options(self, project_options: 'MutableKeyedOptionDictType', subproject: SubProject) -> None:
+        for key, value in project_options.items():
             if not key.is_project():
                 continue
             if key not in self.optstore:
-                self.optstore[key] = value
+                self.optstore.add_project_option(key, value)
                 continue
             if key.subproject != subproject:
                 raise MesonBugException(f'Tried to set an option for subproject {key.subproject} from {subproject}!')
 
-            oldval = self.optstore[key]
+            oldval = self.optstore.get_value_object(key)
             if type(oldval) is not type(value):
-                self.optstore[key] = value
+                self.optstore.set_value(key, value.value)
             elif oldval.choices != value.choices:
                 # If the choices have changed, use the new value, but attempt
                 # to keep the old options. If they are not valid keep the new
                 # defaults but warn.
-                self.optstore[key] = value
+                self.optstore.set_value_object(key, value)
                 try:
                     value.set_value(oldval.value)
                 except MesonException:
@@ -603,9 +605,9 @@ class CoreData:
                                  fatal=False)
 
         # Find any extranious keys for this project and remove them
-        for key in self.optstore.keys() - options.keys():
+        for key in self.optstore.keys() - project_options.keys():
             if key.is_project() and key.subproject == subproject:
-                del self.optstore[key]
+                self.optstore.remove(key)
 
     def is_cross_build(self, when_building_for: MachineChoice = MachineChoice.HOST) -> bool:
         if when_building_for == MachineChoice.BUILD:
@@ -616,13 +618,13 @@ class CoreData:
         dirty = False
         assert not self.is_cross_build()
         for k in options.BUILTIN_OPTIONS_PER_MACHINE:
-            o = self.optstore[k]
-            dirty |= self.optstore[k.as_build()].set_value(o.value)
+            o = self.optstore.get_value_object(k)
+            dirty |= self.optstore.set_value(k.as_build(), o.value)
         for bk, bv in self.optstore.items():
             if bk.machine is MachineChoice.BUILD:
                 hk = bk.as_host()
                 try:
-                    hv = self.optstore[hk]
+                    hv = self.optstore.get_value_object(hk)
                     dirty |= bv.set_value(hv.value)
                 except KeyError:
                     continue
@@ -637,10 +639,10 @@ class CoreData:
         pfk = OptionKey('prefix')
         if pfk in opts_to_set:
             prefix = self.sanitize_prefix(opts_to_set[pfk])
-            dirty |= self.optstore[OptionKey('prefix')].set_value(prefix)
+            dirty |= self.optstore.set_value('prefix', prefix)
             for key in options.BUILTIN_DIR_NOPREFIX_OPTIONS:
                 if key not in opts_to_set:
-                    dirty |= self.optstore[key].set_value(options.BUILTIN_OPTIONS[key].prefixed_default(key, prefix))
+                    dirty |= self.optstore.set_value(key, options.BUILTIN_OPTIONS[key].prefixed_default(key, prefix))
 
         unknown_options: T.List[OptionKey] = []
         for k, v in opts_to_set.items():
@@ -690,7 +692,7 @@ class CoreData:
             # Always test this using the HOST machine, as many builtin options
             # are not valid for the BUILD machine, but the yielding value does
             # not differ between them even when they are valid for both.
-            if subproject and k.is_builtin() and self.optstore[k.evolve(subproject='', machine=MachineChoice.HOST)].yielding:
+            if subproject and k.is_builtin() and self.optstore.get_value_object(k.evolve(subproject='', machine=MachineChoice.HOST)).yielding:
                 continue
             # Skip base, compiler, and backend options, they are handled when
             # adding languages and setting backend.
@@ -703,14 +705,14 @@ class CoreData:
 
         self.set_options(options, subproject=subproject, first_invocation=env.first_invocation)
 
-    def add_compiler_options(self, options: MutableKeyedOptionDictType, lang: str, for_machine: MachineChoice,
+    def add_compiler_options(self, c_options: MutableKeyedOptionDictType, lang: str, for_machine: MachineChoice,
                              env: Environment, subproject: str) -> None:
-        for k, o in options.items():
+        for k, o in c_options.items():
             value = env.options.get(k)
             if value is not None:
                 o.set_value(value)
                 if not subproject:
-                    self.optstore[k] = o  # override compiler option on reconfigure
+                    self.optstore.set_value_object(k, o)  # override compiler option on reconfigure
             self.optstore.setdefault(k, o)
 
             if subproject:
@@ -718,7 +720,7 @@ class CoreData:
                 value = env.options.get(sk) or value
                 if value is not None:
                     o.set_value(value)
-                    self.optstore[sk] = o  # override compiler option on reconfigure
+                    self.optstore.set_value_object(sk, o)  # override compiler option on reconfigure
                 self.optstore.setdefault(sk, o)
 
     def add_lang_args(self, lang: str, comp: T.Type['Compiler'],
@@ -742,19 +744,19 @@ class CoreData:
             else:
                 skey = key
             if skey not in self.optstore:
-                self.optstore[skey] = copy.deepcopy(compilers.base_options[key])
+                self.optstore.add_system_option(skey, copy.deepcopy(compilers.base_options[key]))
                 if skey in env.options:
-                    self.optstore[skey].set_value(env.options[skey])
+                    self.optstore.set_value(skey, env.options[skey])
                     enabled_opts.append(skey)
                 elif subproject and key in env.options:
-                    self.optstore[skey].set_value(env.options[key])
+                    self.optstore.set_value(skey, env.options[key])
                     enabled_opts.append(skey)
                 if subproject and key not in self.optstore:
-                    self.optstore[key] = copy.deepcopy(self.optstore[skey])
+                    self.optstore.add_system_option(key, copy.deepcopy(self.optstore.get_value_object(skey)))
             elif skey in env.options:
-                self.optstore[skey].set_value(env.options[skey])
+                self.optstore.set_value(skey, env.options[skey])
             elif subproject and key in env.options:
-                self.optstore[skey].set_value(env.options[key])
+                self.optstore.set_value(skey, env.options[key])
         self.emit_base_options_warnings(enabled_opts)
 
     def emit_base_options_warnings(self, enabled_opts: T.List[OptionKey]) -> None:
@@ -905,7 +907,15 @@ class OptionsView(abc.Mapping):
         if not key.is_project():
             opt = self.original_options.get(key)
             if opt is None or opt.yielding:
-                opt = self.original_options[key.as_root()]
+                key2 = key.as_root()
+                # This hack goes away once wi start using OptionStore
+                # to hold overrides.
+                if isinstance(self.original_options, options.OptionStore):
+                    if key2 not in self.original_options:
+                        raise KeyError
+                    opt = self.original_options.get_value_object(key2)
+                else:
+                    opt = self.original_options[key2]
         else:
             opt = self.original_options[key]
             if opt.yielding:
@@ -917,6 +927,16 @@ class OptionsView(abc.Mapping):
                 opt.set_value(override_value)
         return opt
 
+    def get_value(self, key: T.Union[str, OptionKey]):
+        if isinstance(key, str):
+            key = OptionKey(key)
+        return self[key].value
+
+    def set_value(self, key: T.Union[str, OptionKey], value: T.Union[str, int, bool, T.List[str]]):
+        if isinstance(key, str):
+            key = OptionKey(key)
+        self.overrides[key] = value
+
     def __iter__(self) -> T.Iterator[OptionKey]:
         return iter(self.original_options)
 
diff --git a/mesonbuild/dependencies/boost.py b/mesonbuild/dependencies/boost.py
index 39b3cfe..02aa1ea 100644
--- a/mesonbuild/dependencies/boost.py
+++ b/mesonbuild/dependencies/boost.py
@@ -580,8 +580,8 @@ class BoostDependency(SystemDependency):
         # MSVC is very picky with the library tags
         vscrt = ''
         try:
-            crt_val = self.env.coredata.optstore[mesonlib.OptionKey('b_vscrt')].value
-            buildtype = self.env.coredata.optstore[mesonlib.OptionKey('buildtype')].value
+            crt_val = self.env.coredata.optstore.get_value('b_vscrt')
+            buildtype = self.env.coredata.optstore.get_value('buildtype')
             vscrt = self.clib_compiler.get_crt_compile_args(crt_val, buildtype)[0]
         except (KeyError, IndexError, AttributeError):
             pass
diff --git a/mesonbuild/dependencies/pkgconfig.py b/mesonbuild/dependencies/pkgconfig.py
index b6647b4..a87f413 100644
--- a/mesonbuild/dependencies/pkgconfig.py
+++ b/mesonbuild/dependencies/pkgconfig.py
@@ -238,7 +238,7 @@ class PkgConfigCLI(PkgConfigInterface):
     def _get_env(self, uninstalled: bool = False) -> EnvironmentVariables:
         env = EnvironmentVariables()
         key = OptionKey('pkg_config_path', machine=self.for_machine)
-        extra_paths: T.List[str] = self.env.coredata.optstore[key].value[:]
+        extra_paths: T.List[str] = self.env.coredata.optstore.get_value(key)[:]
         if uninstalled:
             uninstalled_path = Path(self.env.get_build_dir(), 'meson-uninstalled').as_posix()
             if uninstalled_path not in extra_paths:
@@ -397,7 +397,7 @@ class PkgConfigDependency(ExternalDependency):
         #
         # Only prefix_libpaths are reordered here because there should not be
         # too many system_libpaths to cause library version issues.
-        pkg_config_path: T.List[str] = self.env.coredata.optstore[OptionKey('pkg_config_path', machine=self.for_machine)].value
+        pkg_config_path: T.List[str] = self.env.coredata.optstore.get_value(OptionKey('pkg_config_path', machine=self.for_machine))
         pkg_config_path = self._convert_mingw_paths(pkg_config_path)
         prefix_libpaths = OrderedSet(sort_libpaths(list(prefix_libpaths), pkg_config_path))
         system_libpaths: OrderedSet[str] = OrderedSet()
diff --git a/mesonbuild/dependencies/python.py b/mesonbuild/dependencies/python.py
index 2ec7b9d..27340eb 100644
--- a/mesonbuild/dependencies/python.py
+++ b/mesonbuild/dependencies/python.py
@@ -297,7 +297,7 @@ class PythonSystemDependency(SystemDependency, _PythonDependencyBase):
                     is_debug_build = debug or buildtype == 'debug'
                     vscrt_debug = False
                     if mesonlib.OptionKey('b_vscrt') in self.env.coredata.optstore:
-                        vscrt = self.env.coredata.optstore[mesonlib.OptionKey('b_vscrt')].value
+                        vscrt = self.env.coredata.optstore.get_value('b_vscrt')
                         if vscrt in {'mdd', 'mtd', 'from_buildtype', 'static_from_buildtype'}:
                             vscrt_debug = True
                     if is_debug_build and vscrt_debug and not self.variables.get('Py_DEBUG'):
diff --git a/mesonbuild/dependencies/qt.py b/mesonbuild/dependencies/qt.py
index cc80ce8..86e3214 100644
--- a/mesonbuild/dependencies/qt.py
+++ b/mesonbuild/dependencies/qt.py
@@ -298,7 +298,7 @@ class QmakeQtDependency(_QtBase, ConfigToolDependency, metaclass=abc.ABCMeta):
         # compiler supports it.
         is_debug = self.env.coredata.get_option(mesonlib.OptionKey('buildtype')) == 'debug'
         if mesonlib.OptionKey('b_vscrt') in self.env.coredata.optstore:
-            if self.env.coredata.optstore[mesonlib.OptionKey('b_vscrt')].value in {'mdd', 'mtd'}:
+            if self.env.coredata.optstore.get_value('b_vscrt') in {'mdd', 'mtd'}:
                 is_debug = True
         modules_lib_suffix = _get_modules_lib_suffix(self.version, self.env.machines[self.for_machine], is_debug)
 
diff --git a/mesonbuild/interpreter/interpreter.py b/mesonbuild/interpreter/interpreter.py
index a423ed8..ef28d86 100644
--- a/mesonbuild/interpreter/interpreter.py
+++ b/mesonbuild/interpreter/interpreter.py
@@ -1013,7 +1013,7 @@ class Interpreter(InterpreterBase, HoldableObject):
                              kwargs: kwtypes.DoSubproject) -> SubprojectHolder:
         from ..cmake import CMakeInterpreter
         with mlog.nested(subp_name):
-            prefix = self.coredata.optstore[OptionKey('prefix')].value
+            prefix = self.coredata.optstore.get_value('prefix')
 
             from ..modules.cmake import CMakeSubprojectOptions
             options = kwargs.get('options') or CMakeSubprojectOptions()
@@ -1061,9 +1061,9 @@ class Interpreter(InterpreterBase, HoldableObject):
                     return v
 
         try:
-            opt = self.coredata.optstore[key]
+            opt = self.coredata.optstore.get_value_object(key)
             if opt.yielding and key.subproject and key.as_root() in self.coredata.optstore:
-                popt = self.coredata.optstore[key.as_root()]
+                popt = self.coredata.optstore.get_value_object(key.as_root())
                 if type(opt) is type(popt):
                     opt = popt
                 else:
@@ -1543,7 +1543,7 @@ class Interpreter(InterpreterBase, HoldableObject):
             if self.subproject:
                 options = {}
                 for k in comp.get_options():
-                    v = copy.copy(self.coredata.optstore[k])
+                    v = copy.copy(self.coredata.optstore.get_value_object(k))
                     k = k.evolve(subproject=self.subproject)
                     options[k] = v
                 self.coredata.add_compiler_options(options, lang, for_machine, self.environment, self.subproject)
@@ -3045,9 +3045,9 @@ class Interpreter(InterpreterBase, HoldableObject):
             return
         if OptionKey('b_sanitize') not in self.coredata.optstore:
             return
-        if (self.coredata.optstore[OptionKey('b_lundef')].value and
-                self.coredata.optstore[OptionKey('b_sanitize')].value != 'none'):
-            value = self.coredata.optstore[OptionKey('b_sanitize')].value
+        if (self.coredata.optstore.get_value('b_lundef') and
+                self.coredata.optstore.get_value('b_sanitize') != 'none'):
+            value = self.coredata.optstore.get_value('b_sanitize')
             mlog.warning(textwrap.dedent(f'''\
                     Trying to use {value} sanitizer on Clang with b_lundef.
                     This will probably not work.
diff --git a/mesonbuild/interpreter/interpreterobjects.py b/mesonbuild/interpreter/interpreterobjects.py
index f5dafa7..32f05ba 100644
--- a/mesonbuild/interpreter/interpreterobjects.py
+++ b/mesonbuild/interpreter/interpreterobjects.py
@@ -24,7 +24,7 @@ from ..interpreterbase import (
 from ..interpreter.type_checking import NoneType, ENV_KW, ENV_SEPARATOR_KW, PKGCONFIG_DEFINE_KW
 from ..dependencies import Dependency, ExternalLibrary, InternalDependency
 from ..programs import ExternalProgram
-from ..mesonlib import HoldableObject, OptionKey, listify, Popen_safe
+from ..mesonlib import HoldableObject, listify, Popen_safe
 
 import typing as T
 
@@ -90,7 +90,7 @@ class FeatureOptionHolder(ObjectHolder[options.UserFeatureOption]):
         super().__init__(option, interpreter)
         if option and option.is_auto():
             # TODO: we need to cast here because options is not a TypedDict
-            auto = T.cast('options.UserFeatureOption', self.env.coredata.optstore[OptionKey('auto_features')])
+            auto = T.cast('options.UserFeatureOption', self.env.coredata.optstore.get_value_object('auto_features'))
             self.held_object = copy.copy(auto)
             self.held_object.name = option.name
         self.methods.update({'enabled': self.enabled_method,
diff --git a/mesonbuild/mconf.py b/mesonbuild/mconf.py
index 0ed7c92..1f167df 100644
--- a/mesonbuild/mconf.py
+++ b/mesonbuild/mconf.py
@@ -229,7 +229,7 @@ class Conf:
             return
         if title:
             self.add_title(title)
-        auto = T.cast('options.UserFeatureOption', self.coredata.optstore[OptionKey('auto_features')])
+        auto = T.cast('options.UserFeatureOption', self.coredata.optstore.get_value_object('auto_features'))
         for k, o in sorted(opts.items()):
             printable_value = o.printable_value()
             root = k.as_root()
diff --git a/mesonbuild/modules/gnome.py b/mesonbuild/modules/gnome.py
index f46e4f5..cab7c76 100644
--- a/mesonbuild/modules/gnome.py
+++ b/mesonbuild/modules/gnome.py
@@ -906,7 +906,7 @@ class GnomeModule(ExtensionModule):
             if state.project_args.get(lang):
                 cflags += state.project_args[lang]
             if mesonlib.OptionKey('b_sanitize') in compiler.base_options:
-                sanitize = state.environment.coredata.optstore[mesonlib.OptionKey('b_sanitize')].value
+                sanitize = state.environment.coredata.optstore.get_value('b_sanitize')
                 cflags += compiler.sanitizer_compile_args(sanitize)
                 sanitize = sanitize.split(',')
                 # These must be first in ldflags
diff --git a/mesonbuild/modules/python.py b/mesonbuild/modules/python.py
index 3f7affe..b599a5e 100644
--- a/mesonbuild/modules/python.py
+++ b/mesonbuild/modules/python.py
@@ -205,7 +205,7 @@ class PythonInstallation(_ExternalProgramHolder['PythonExternalProgram']):
 
                 new_link_args = mesonlib.extract_as_list(kwargs, 'link_args')
 
-                is_debug = self.interpreter.environment.coredata.optstore[OptionKey('debug')].value
+                is_debug = self.interpreter.environment.coredata.optstore.get_value('debug')
                 if is_debug:
                     new_link_args.append(python_windows_debug_link_exception)
                 else:
diff --git a/mesonbuild/msetup.py b/mesonbuild/msetup.py
index 8f561e4..931b1eb 100644
--- a/mesonbuild/msetup.py
+++ b/mesonbuild/msetup.py
@@ -273,9 +273,9 @@ class MesonApp:
 
             # collect warnings about unsupported build configurations; must be done after full arg processing
             # by Interpreter() init, but this is most visible at the end
-            if env.coredata.optstore[mesonlib.OptionKey('backend')].value == 'xcode':
+            if env.coredata.optstore.get_value('backend') == 'xcode':
                 mlog.warning('xcode backend is currently unmaintained, patches welcome')
-            if env.coredata.optstore[mesonlib.OptionKey('layout')].value == 'flat':
+            if env.coredata.optstore.get_value('layout') == 'flat':
                 mlog.warning('-Dlayout=flat is unsupported and probably broken. It was a failed experiment at '
                              'making Windows build artifacts runnable while uninstalled, due to PATH considerations, '
                              'but was untested by CI and anyways breaks reasonable use of conflicting targets in different subdirs. '
diff --git a/mesonbuild/options.py b/mesonbuild/options.py
index 6ffcf1a..435c53d 100644
--- a/mesonbuild/options.py
+++ b/mesonbuild/options.py
@@ -481,16 +481,40 @@ class OptionStore:
     def __len__(self):
         return len(self.d)
 
-    def __setitem__(self, key, value):
-        self.d[key] = value
+    def ensure_key(self,key: T.Union[OptionKey, str]) -> OptionKey:
+        if isinstance(key, str):
+            return OptionKey(key)
+        return key
 
-    def __getitem__(self, key):
-        return self.d[key]
+    def get_value_object(self, key: T.Union[OptionKey, str]) -> 'UserOption[T.Any]':
+        return self.d[self.ensure_key(key)]
 
-    def __delitem__(self, key):
+    def get_value(self, key: T.Union[OptionKey, str]) -> 'T.Any':
+        return self.get_value_object(key).value
+
+    def add_system_option(self, key: T.Union[OptionKey, str], valobj: 'UserOption[T.Any'):
+        key = self.ensure_key(key)
+        self.d[key] = valobj
+
+    def add_project_option(self, key: T.Union[OptionKey, str], valobj: 'UserOption[T.Any]'):
+        key = self.ensure_key(key)
+        self.d[key] = valobj
+
+    def set_value(self, key: T.Union[OptionKey, str], new_value: 'T.Any') -> bool:
+        key  = self.ensure_key(key)
+        return self.d[key].set_value(new_value)
+
+    # FIXME, this should be removed.or renamed to "change_type_of_existing_object" or something like that
+    def set_value_object(self, key: T.Union[OptionKey, str], new_object: 'UserOption[T.Any]') -> bool:
+        key  = self.ensure_key(key)
+        self.d[key] = new_object
+
+
+    def remove(self, key):
         del self.d[key]
 
     def __contains__(self, key):
+        key = self.ensure_key(key)
         return key in self.d
 
     def __repr__(self):
diff --git a/run_tests.py b/run_tests.py
index 5b229d7..8ab53a1 100755
--- a/run_tests.py
+++ b/run_tests.py
@@ -151,7 +151,7 @@ def get_fake_env(sdir='', bdir=None, prefix='', opts=None):
     if opts is None:
         opts = get_fake_options(prefix)
     env = Environment(sdir, bdir, opts)
-    env.coredata.optstore[OptionKey('args', lang='c')] = FakeCompilerOptions()
+    env.coredata.optstore.set_value_object(OptionKey('args', lang='c'),  FakeCompilerOptions())
     env.machines.host.cpu_family = 'x86_64' # Used on macOS inside find_library
     # Invalidate cache when using a different Environment object.
     clear_meson_configure_class_caches()
diff --git a/unittests/allplatformstests.py b/unittests/allplatformstests.py
index 042f210..201dae6 100644
--- a/unittests/allplatformstests.py
+++ b/unittests/allplatformstests.py
@@ -2621,35 +2621,35 @@ class AllPlatformTests(BasePlatformTests):
         out = self.init(testdir, extra_args=['--profile-self', '--fatal-meson-warnings'])
         self.assertNotIn('[default: true]', out)
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('default_library')].value, 'static')
-        self.assertEqual(obj.optstore[OptionKey('warning_level')].value, '1')
-        self.assertEqual(obj.optstore[OptionKey('set_sub_opt')].value, True)
-        self.assertEqual(obj.optstore[OptionKey('subp_opt', 'subp')].value, 'default3')
+        self.assertEqual(obj.optstore.get_value('default_library'), 'static')
+        self.assertEqual(obj.optstore.get_value('warning_level'), '1')
+        self.assertEqual(obj.optstore.get_value('set_sub_opt'), True)
+        self.assertEqual(obj.optstore.get_value(OptionKey('subp_opt', 'subp')), 'default3')
         self.wipe()
 
         # warning_level is special, it's --warnlevel instead of --warning-level
         # for historical reasons
         self.init(testdir, extra_args=['--warnlevel=2', '--fatal-meson-warnings'])
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('warning_level')].value, '2')
+        self.assertEqual(obj.optstore.get_value('warning_level'), '2')
         self.setconf('--warnlevel=3')
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('warning_level')].value, '3')
+        self.assertEqual(obj.optstore.get_value('warning_level'), '3')
         self.setconf('--warnlevel=everything')
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('warning_level')].value, 'everything')
+        self.assertEqual(obj.optstore.get_value('warning_level'), 'everything')
         self.wipe()
 
         # But when using -D syntax, it should be 'warning_level'
         self.init(testdir, extra_args=['-Dwarning_level=2', '--fatal-meson-warnings'])
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('warning_level')].value, '2')
+        self.assertEqual(obj.optstore.get_value('warning_level'), '2')
         self.setconf('-Dwarning_level=3')
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('warning_level')].value, '3')
+        self.assertEqual(obj.optstore.get_value('warning_level'), '3')
         self.setconf('-Dwarning_level=everything')
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('warning_level')].value, 'everything')
+        self.assertEqual(obj.optstore.get_value('warning_level'), 'everything')
         self.wipe()
 
         # Mixing --option and -Doption is forbidden
@@ -2673,15 +2673,15 @@ class AllPlatformTests(BasePlatformTests):
         # --default-library should override default value from project()
         self.init(testdir, extra_args=['--default-library=both', '--fatal-meson-warnings'])
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('default_library')].value, 'both')
+        self.assertEqual(obj.optstore.get_value('default_library'), 'both')
         self.setconf('--default-library=shared')
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('default_library')].value, 'shared')
+        self.assertEqual(obj.optstore.get_value('default_library'), 'shared')
         if self.backend is Backend.ninja:
             # reconfigure target works only with ninja backend
             self.build('reconfigure')
             obj = mesonbuild.coredata.load(self.builddir)
-            self.assertEqual(obj.optstore[OptionKey('default_library')].value, 'shared')
+            self.assertEqual(obj.optstore.get_value('default_library'), 'shared')
         self.wipe()
 
         # Should fail on unknown options
@@ -2718,22 +2718,22 @@ class AllPlatformTests(BasePlatformTests):
         # Test we can set subproject option
         self.init(testdir, extra_args=['-Dsubp:subp_opt=foo', '--fatal-meson-warnings'])
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('subp_opt', 'subp')].value, 'foo')
+        self.assertEqual(obj.optstore.get_value(OptionKey('subp_opt', 'subp')), 'foo')
         self.wipe()
 
         # c_args value should be parsed with split_args
         self.init(testdir, extra_args=['-Dc_args=-Dfoo -Dbar "-Dthird=one two"', '--fatal-meson-warnings'])
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('args', lang='c')].value, ['-Dfoo', '-Dbar', '-Dthird=one two'])
+        self.assertEqual(obj.optstore.get_value(OptionKey('args', lang='c')), ['-Dfoo', '-Dbar', '-Dthird=one two'])
 
         self.setconf('-Dc_args="foo bar" one two')
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('args', lang='c')].value, ['foo bar', 'one', 'two'])
+        self.assertEqual(obj.optstore.get_value(OptionKey('args', lang='c')), ['foo bar', 'one', 'two'])
         self.wipe()
 
         self.init(testdir, extra_args=['-Dset_percent_opt=myoption%', '--fatal-meson-warnings'])
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('set_percent_opt')].value, 'myoption%')
+        self.assertEqual(obj.optstore.get_value('set_percent_opt'), 'myoption%')
         self.wipe()
 
         # Setting a 2nd time the same option should override the first value
@@ -2744,19 +2744,19 @@ class AllPlatformTests(BasePlatformTests):
                                            '-Dc_args=-Dfoo', '-Dc_args=-Dbar',
                                            '-Db_lundef=false', '--fatal-meson-warnings'])
             obj = mesonbuild.coredata.load(self.builddir)
-            self.assertEqual(obj.optstore[OptionKey('bindir')].value, 'bar')
-            self.assertEqual(obj.optstore[OptionKey('buildtype')].value, 'release')
-            self.assertEqual(obj.optstore[OptionKey('b_sanitize')].value, 'thread')
-            self.assertEqual(obj.optstore[OptionKey('args', lang='c')].value, ['-Dbar'])
+            self.assertEqual(obj.optstore.get_value('bindir'), 'bar')
+            self.assertEqual(obj.optstore.get_value('buildtype'), 'release')
+            self.assertEqual(obj.optstore.get_value('b_sanitize'), 'thread')
+            self.assertEqual(obj.optstore.get_value(OptionKey('args', lang='c')), ['-Dbar'])
             self.setconf(['--bindir=bar', '--bindir=foo',
                           '-Dbuildtype=release', '-Dbuildtype=plain',
                           '-Db_sanitize=thread', '-Db_sanitize=address',
                           '-Dc_args=-Dbar', '-Dc_args=-Dfoo'])
             obj = mesonbuild.coredata.load(self.builddir)
-            self.assertEqual(obj.optstore[OptionKey('bindir')].value, 'foo')
-            self.assertEqual(obj.optstore[OptionKey('buildtype')].value, 'plain')
-            self.assertEqual(obj.optstore[OptionKey('b_sanitize')].value, 'address')
-            self.assertEqual(obj.optstore[OptionKey('args', lang='c')].value, ['-Dfoo'])
+            self.assertEqual(obj.optstore.get_value('bindir'), 'foo')
+            self.assertEqual(obj.optstore.get_value('buildtype'), 'plain')
+            self.assertEqual(obj.optstore.get_value('b_sanitize'), 'address')
+            self.assertEqual(obj.optstore.get_value(OptionKey('args', lang='c')), ['-Dfoo'])
             self.wipe()
         except KeyError:
             # Ignore KeyError, it happens on CI for compilers that does not
@@ -2770,25 +2770,25 @@ class AllPlatformTests(BasePlatformTests):
         # Verify default values when passing no args
         self.init(testdir)
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('warning_level')].value, '0')
+        self.assertEqual(obj.optstore.get_value('warning_level'), '0')
         self.wipe()
 
         # verify we can override w/ --warnlevel
         self.init(testdir, extra_args=['--warnlevel=1'])
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('warning_level')].value, '1')
+        self.assertEqual(obj.optstore.get_value('warning_level'), '1')
         self.setconf('--warnlevel=0')
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('warning_level')].value, '0')
+        self.assertEqual(obj.optstore.get_value('warning_level'), '0')
         self.wipe()
 
         # verify we can override w/ -Dwarning_level
         self.init(testdir, extra_args=['-Dwarning_level=1'])
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('warning_level')].value, '1')
+        self.assertEqual(obj.optstore.get_value('warning_level'), '1')
         self.setconf('-Dwarning_level=0')
         obj = mesonbuild.coredata.load(self.builddir)
-        self.assertEqual(obj.optstore[OptionKey('warning_level')].value, '0')
+        self.assertEqual(obj.optstore.get_value('warning_level'), '0')
         self.wipe()
 
     def test_feature_check_usage_subprojects(self):
diff --git a/unittests/datatests.py b/unittests/datatests.py
index b596446..b7b2d32 100644
--- a/unittests/datatests.py
+++ b/unittests/datatests.py
@@ -163,9 +163,9 @@ class DataTests(unittest.TestCase):
             else:
                 raise RuntimeError(f'Invalid debug value {debug!r} in row:\n{m.group()}')
             env.coredata.set_option(OptionKey('buildtype'), buildtype)
-            self.assertEqual(env.coredata.optstore[OptionKey('buildtype')].value, buildtype)
-            self.assertEqual(env.coredata.optstore[OptionKey('optimization')].value, opt)
-            self.assertEqual(env.coredata.optstore[OptionKey('debug')].value, debug)
+            self.assertEqual(env.coredata.optstore.get_value('buildtype'), buildtype)
+            self.assertEqual(env.coredata.optstore.get_value('optimization'), opt)
+            self.assertEqual(env.coredata.optstore.get_value('debug'), debug)
 
     def test_cpu_families_documented(self):
         with open("docs/markdown/Reference-tables.md", encoding='utf-8') as f:
diff --git a/unittests/internaltests.py b/unittests/internaltests.py
index 42cc41e..fe9f0d4 100644
--- a/unittests/internaltests.py
+++ b/unittests/internaltests.py
@@ -625,7 +625,7 @@ class InternalTests(unittest.TestCase):
             env = get_fake_env()
             compiler = detect_c_compiler(env, MachineChoice.HOST)
             env.coredata.compilers.host = {'c': compiler}
-            env.coredata.optstore[OptionKey('link_args', lang='c')] = FakeCompilerOptions()
+            env.coredata.optstore.set_value_object(OptionKey('link_args', lang='c'), FakeCompilerOptions())
             p1 = Path(tmpdir) / '1'
             p2 = Path(tmpdir) / '2'
             p1.mkdir()
diff --git a/unittests/linuxliketests.py b/unittests/linuxliketests.py
index 1e8038f..ea86784 100644
--- a/unittests/linuxliketests.py
+++ b/unittests/linuxliketests.py
@@ -1124,7 +1124,7 @@ class LinuxlikeTests(BasePlatformTests):
         # option, adding the meson-uninstalled directory to it.
         PkgConfigInterface.setup_env({}, env, MachineChoice.HOST, uninstalled=True)
 
-        pkg_config_path = env.coredata.optstore[OptionKey('pkg_config_path')].value
+        pkg_config_path = env.coredata.optstore.get_value('pkg_config_path')
         self.assertEqual(pkg_config_path, [pkg_dir])
 
     @skipIfNoPkgconfig