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Re: [RFA] Sorting symbols. Again.
- From: Daniel Jacobowitz <drow at mvista dot com>
- To: Syd Polk <spolk at apple dot com>
- Cc: gdb-patches at sources dot redhat dot com, insight at sources dot redhat dot com,keiths at cygnus dot com, Elena Zannoni <ezannoni at cygnus dot com>
- Date: Wed, 30 Jan 2002 17:37:35 -0500
- Subject: Re: [RFA] Sorting symbols. Again.
- References: <20020130005430.A28900@nevyn.them.org> <DE5AE60F-15CC-11D6-99A6-0050E4C09301@apple.com>
On Wed, Jan 30, 2002 at 02:01:10PM -0800, Syd Polk wrote:
>
> Where is sort_funcVals called from? It it called pretty close to the Tcl
> layer? If so, you might want to use "lsort -command foo" from the tcl
> level and implement the comparison command in C. Given that the sort
> command you are using pares down to a simple strcmp, this would be much
> cleaner than doing what you are doing.
It's called from gdb_listfuncs. Are the TCL functions exported by
insight generally available to some kind of user scripts, or can I
change callers?
In fact, I see that one of the two callers already sorts the list
itself.
> You should not have to loop through the objects in list_objv to Incr or
> Decr their refCounts. Tcl_SetListObj does that automatically. They are
> created with a refCount of 0; Tcl_SetListObj incrs them to 1. What you
> are doing is creating them, setting them to 1, calling Tcl_SetListObj
> (which incrs them to 2), and the decrementing them back to 1.
>
> Also, it is really, really slimy to create Tcl_Objs without going
> through Tcl_New*Obj.
>
> I would much prefer that you duplicate the list, and then call "lsort".
> Pseudo-code:
>
> Tcl_Obj *commandArray[2];
>
> Tcl_ListObjGetElements (NULL, result_ptr->obj_ptr, &list_objc,
> &list_objv);
> newList = Tcl_NewListObj(list_objc, list_objv);
> commandArray[1] = newList;
> Tcl_IncrRefCount(newList);
> commandArray[0] = Tcl_NewObjFromString("lsort");
> Tcl_IncrRefCount(commandArray[0]);
> result = Tcl_EvalObjv(interp, 2, commandArray);
> Tcl_DecrRefCount(commandArray[0]);
>
> /* newList now has sorted list. */
>
> I am not a maintainer, but I worked in the core of Tcl for a couple of
> years for John O., and doing block allocates of Tcl_Objs is just asking
> for trouble, and will lead to problems if insight is ever compiled to
> TCL_MEM_DEBUG, or other things.
I don't think I did anything of the sort; but perhaps I misunderstood
Tcl_SetListObj. The documentation doesn't say anything about how to
allocate the objv. The refcount mess was because of using SetListObj,
but I suppose I understand now that creating a new object and then
destroying the old one would have worked out cleaner. Hopefully the
above will be accepted and I can delete the sort entirely :)
Thanks for the helpful comments.
--
Daniel Jacobowitz Carnegie Mellon University
MontaVista Software Debian GNU/Linux Developer