diff options
Diffstat (limited to 'gdb/doc/gdb.texinfo')
| -rw-r--r-- | gdb/doc/gdb.texinfo | 46 |
1 files changed, 42 insertions, 4 deletions
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index a74d10e..8d93565 100644 --- a/gdb/doc/gdb.texinfo +++ b/gdb/doc/gdb.texinfo @@ -19312,7 +19312,9 @@ access this functionality: @item @code{-var-info-type} @tab show the type of this variable object @item @code{-var-info-expression} -@tab print what this variable object represents +@tab print parent-relative expression that this variable object represents +@item @code{-var-info-path-expression} +@tab print full expression that this variable object represents @item @code{-var-show-attributes} @tab is this variable editable? does it exist here? @item @code{-var-evaluate-expression} @@ -19513,14 +19515,50 @@ returned as a string in the same format as it is output by the -var-info-expression @var{name} @end smallexample -Returns what is represented by the variable object @var{name}: +Returns a string that is suitable for presenting this +variable object in user interface. The string is generally +not valid expression in the current language, and cannot be evaluated. + +For example, if @code{a} is an array, and variable object +@code{A} was created for @code{a}, then we'll get this output: @smallexample - lang=@var{lang-spec},exp=@var{expression} +(gdb) -var-info-expression A.1 +^done,lang="C",exp="1" @end smallexample @noindent -where @var{lang-spec} is @code{@{"C" | "C++" | "Java"@}}. +Here, the values of @code{lang} can be @code{@{"C" | "C++" | "Java"@}}. + +Note that the output of the @code{-var-list-children} command also +includes those expressions, so the @code{-var-info-expression} command +is of limited use. + +@subheading The @code{-var-info-path-expression} Command +@findex -var-info-path-expression + +@subsubheading Synopsis + +@smallexample + -var-info-path-expression @var{name} +@end smallexample + +Returns an expression that can be evaluated in the current +context and will yield the same value that a variable object has. +Compare this with the @code{-var-info-expression} command, which +result can be used only for UI presentation. Typical use of +the @code{-var-info-path-expression} command is creating a +watchpoint from a variable object. + +For example, suppose @code{C} is a C@t{++} class, derived from class +@code{Base}, and that the @code{Base} class has a member called +@code{m_size}. Assume a variable @code{c} is has the type of +@code{C} and a variable object @code{C} was created for variable +@code{c}. Then, we'll get this output: +@smallexample +(gdb) -var-info-path-expression C.Base.public.m_size +^done,path_expr=((Base)c).m_size) +@end smallexample @subheading The @code{-var-show-attributes} Command @findex -var-show-attributes |