* Re: MI: variable objects: children naming
2006-03-17 17:23 ` Daniel Jacobowitz
@ 2006-03-17 19:42 ` Jim Ingham
2006-03-20 23:11 ` Vladimir Prus
1 sibling, 0 replies; 4+ messages in thread
From: Jim Ingham @ 2006-03-17 19:42 UTC (permalink / raw)
To: Daniel Jacobowitz; +Cc: Vladimir Prus, gdb
You need to two different things.
If you are displaying a variable tree, then you need just the name of
the child in it's parent. That's what the "exp" element is for. I
guess for the array, you could argue that the exp should be "[0]",
not "0". That might help you print it without the UI having to do
any work. I'm not sure why we didn't change this as well. But in
our version of gdb we also return the typecode, and the UI can use
that to hint on how to print it. So from Apple's gdb you would get
(for int foo[3]):
-var-create - * foo
^done,name="var1",numchild="3",type="int
[3]",typecode="ARRAY",dynamic_type="",in_scope="true",block_start_addr="
0x00002a80",block_end_addr="0x00002afc"
(gdb)
-var-list-children var1
^done,numchild="3",children={child=
{name="var1.0",exp="0",numchild="0",type="int",typecode="INT",dynamic_ty
pe=""},child=
{name="var1.1",exp="1",numchild="0",type="int",typecode="INT",dynamic_ty
pe=""},child=
{name="var1.2",exp="2",numchild="0",type="int",typecode="INT",dynamic_ty
pe=""}}
At other times, you need to take a child varobj and figure out what
the full expression for it should be. Note this can be non-trivial
to cons up from just the names. For instance, if you have a class
that inherits from two other classes, each of which has the same
named member, you have to cons up a moderately complex expression
involving casts to get back from one of these child varobj's to an
expression you can give gdb, and have it print the right value...
That's what the -var-info-path-expression is for. We use it, for
example, in the right-click menu on the variables view, where you can
choose "Add to Expressions Window" or "View Memory", etc...
Jim
On Mar 17, 2006, at 9:07 AM, Daniel Jacobowitz wrote:
> On Fri, Mar 17, 2006 at 04:20:07PM +0300, Vladimir Prus wrote:
>> (gdb)
>> -var-create TMP * m
>> ^done,name="TMP",numchild="3",type="int [3]"
>> (gdb)
>> -var-list-children TMP
>> ^done,numchild="3",children=[
>> child={name="TMP.0",exp="0",numchild="0",type="int"},
>> child={name="TMP.1",exp="1",numchild="0",type="int"},
>> child={name="TMP.2",exp="2",numchild="0",type="int"}]
>>
>>
>> Suppose I display this to the user as a tree. If user selects
>> first child of
>> "m" and wants to set watchpoint on it, I need to know the full
>> name of
>> first child of "m". In C++, that would be m[0].
>>
>> However, the information gdb prints does not allow me to compute m
>> [0]:
>
> Is this the only thing you need the name for, or is it useful for
> other
> purposes in the user interface too? (Honest question - I have no
> idea.)
>
> If watchpoints are the only reason, then you could have a variant of a
> watchpoint command which took a varobj.
>
>> - Calling '-var-info-expression TMP.0' returns:
>> ^done,lang="C++",exp="0"
>>
>> It seems like Apple version has new command -var-info-path-
>> expression, which
>> is not present in FSF version, and which supposedly will produce "m
>> [0]".
>
> We'd have to ask Jim for the history, but why should we do this
> instead
> of fixing -var-info-expression? That behavior looks pretty wrong!
>
> --
> Daniel Jacobowitz
> CodeSourcery
Jim Ingham
Apple Developer Tools
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: MI: variable objects: children naming
2006-03-17 17:23 ` Daniel Jacobowitz
2006-03-17 19:42 ` Jim Ingham
@ 2006-03-20 23:11 ` Vladimir Prus
1 sibling, 0 replies; 4+ messages in thread
From: Vladimir Prus @ 2006-03-20 23:11 UTC (permalink / raw)
To: gdb
Daniel Jacobowitz wrote:
>> However, the information gdb prints does not allow me to compute m[0]:
>
> Is this the only thing you need the name for, or is it useful for other
> purposes in the user interface too? (Honest question - I have no
> idea.)
>
Yes, there are other purposes. Say, if you right-click an item in variables
tree and select, in the popup menu, the "Remember" command, the current
value of the item will be shown in a separate area for future reference.
But we need to show the full name of the item there. It's only for user, and
we need full name there.
> If watchpoints are the only reason, then you could have a variant of a
> watchpoint command which took a varobj.
>
>> - Calling '-var-info-expression TMP.0' returns:
>> ^done,lang="C++",exp="0"
>>
>> It seems like Apple version has new command -var-info-path-expression,
>> which is not present in FSF version, and which supposedly will produce
>> "m[0]".
>
> We'd have to ask Jim for the history, but why should we do this instead
> of fixing -var-info-expression? That behavior looks pretty wrong!
Jim has explained this -- 'info-expression' is local name of an item
relative to the parent, while 'info-path-expression' is full name.
- Volodya
^ permalink raw reply [flat|nested] 4+ messages in thread