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authorDylan Baker <dylan@pnwbakers.com>2017-05-01 15:11:01 -0700
committerJussi Pakkanen <jpakkane@gmail.com>2017-05-02 21:57:26 +0300
commita8173630eac1f35914fdc2d918a636ac268b9033 (patch)
treec971b7e0be066df5a2a77f1141eb1517dd3903ef /mesonbuild/scripts/uninstall.py
parentae924b01a006bc1542fe7eaae1d8a933459e8a0a (diff)
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Don't use len() to test emptiness vs not emptiness
Meson has a common pattern of using 'if len(foo) == 0:' or 'if len(foo) != 0:', however, this is a common anti-pattern in python. Instead tests for emptiness/non-emptiness should be done with a simple 'if foo:' or 'if not foo:' Consider the following: >>> import timeit >>> timeit.timeit('if len([]) == 0: pass') 0.10730923599840025 >>> timeit.timeit('if not []: pass') 0.030033907998586074 >>> timeit.timeit('if len(['a', 'b', 'c', 'd']) == 0: pass') 0.1154778649979562 >>> timeit.timeit("if not ['a', 'b', 'c', 'd']: pass") 0.08259823200205574 >>> timeit.timeit('if len("") == 0: pass') 0.089759664999292 >>> timeit.timeit('if not "": pass') 0.02340641999762738 >>> timeit.timeit('if len("foo") == 0: pass') 0.08848102600313723 >>> timeit.timeit('if not "foo": pass') 0.04032287199879647 And for the one additional case of 'if len(foo.strip()) == 0', which can be replaced with 'if not foo.isspace()' >>> timeit.timeit('if len(" ".strip()) == 0: pass') 0.15294511600222904 >>> timeit.timeit('if " ".isspace(): pass') 0.09413968399894657 >>> timeit.timeit('if len(" abc".strip()) == 0: pass') 0.2023209120015963 >>> timeit.timeit('if " abc".isspace(): pass') 0.09571301700270851 In other words, it's always a win to not use len(), when you don't actually want to check the length.
Diffstat (limited to 'mesonbuild/scripts/uninstall.py')
-rw-r--r--mesonbuild/scripts/uninstall.py2
1 files changed, 1 insertions, 1 deletions
diff --git a/mesonbuild/scripts/uninstall.py b/mesonbuild/scripts/uninstall.py
index 85c4bba..1480921 100644
--- a/mesonbuild/scripts/uninstall.py
+++ b/mesonbuild/scripts/uninstall.py
@@ -36,7 +36,7 @@ def do_uninstall(log):
print('\nRemember that files created by custom scripts have not been removed.')
def run(args):
- if len(args) != 0:
+ if args:
print('Weird error.')
return 1
if not os.path.exists(logfile):