Re: [MI] lvalues and variable_editable

[Nick Roberts <nickrob at snap dot net dot nz>]

 > - Why do variable_editable_p and varobj_value_is_changeable_p have to
 > be different?  That is, do we need varobj_value_is_changeable_p to be
 > true for any non-lvals.  If not, we can eliminate one of them.

Taking my earlier example:

-var-create - * "i1 + i2"

As it's not an lvalue it's not editable (variable_editable_p returns 0)
but it's value can surely change (variable_changeable_p returns 1).  So GDB
has to check for this and report any change when -var-update is issued.

While

int m[10]

-var-create - * m

is not editable and not changeable.

Does this show that variable_editable_p and varobj_value_is_changeable_p
are necessarily different?  (One is used to tell the user he can't edit the
value, the other to tell GDB not to bother check for a change in value.)

 > - Why do you need to re-evaluate the expression?  I think we can use
 > var->value, and report anything with a NULL value as non-editable.
 > No point editing it if we can't save it somewhere.

Perhaps you don't.  Currently you can do things like:

(gdb) 
-var-create - * 1/0
^done,name="var1",numchild="0",value="",type="int"
(gdb) 
-var-create - * 0/0
^done,name="var2",numchild="0",value="",type="int"

I was just being cautious, and cut and pasting.

 > Also, I think varobj_value_is_changeable_p was missing from your
 > changelog (if I've correctly understood where one hunk of that patch
 > goes),

OK.

 >        and the patch had "variable_editable_pv" in it.

Sticky fingers, sorry about that.  My version of varobj.c compiles and doesn't
have this, of course.

-- 
Nick                                           http://www.inet.net.nz/~nickrob