[Python-Dev] about line numbers

[Vladimir Marangozov]

Chris, could you please repeat that step by step in more detail?
I'm not sure I understand your suggestions.

Christian Tismer wrote:
>
> Vladimir Marangozov wrote:
> ...
> > I wrote a very rough first implementation of this idea. The files are at:
> >
> > http://sirac.inrialpes.fr/~marangoz/python/lineno/
> >
> > Basically, what I did is:
> >
> > 1) what I said :-)
> > 2) No more SET_LINENO
> > 3) In tracing mode, a copy of the original code is put in an additional
> >    slot (co_tracecode) of the code object. Then it's overwritten with
> >    CALL_TRACE opcodes at the locations returned by PyCode_Line2Addr.
>
> I'd rather keep the original code object as it is, create a copy
> with inserted breakpoints and put that into the frame slot.

You seem to suggest to duplicate the entire code object, right?
And reference the modified duplicata from the current frame?

I actually duplicate only the opcode string (that is, the co_code string
object) and I don't see the point of duplicating the entire code object.

Keeping a reference from the current frame makes sense, but won't it
deallocate the modified version on every frame release (then redo all the
code duplication work for every frame) ?

> Pointing back to the original from there.

I don't understand this. What points back where?

>
> Then I'd redirect the code from the CALL_TRACE opcode completely
> to a user-defined function.

What user-defined function? I don't understand that either...
Except the sys_tracefunc, what other (user-defined) function do we have here?
Is it a Python or a C function?

> Getting rid of the extra code object would be done by this function
> when tracing is off.

How exactly? This seems to be obvious for you, but obviously, not for me ;-)

> It also vanishes automatically when the frame is released.

The function or the extra code object?

>
> > a) how to deallocate the modified code string when tracing is off
>
> By making the copy a frame property which is temporary, I think.

I understood that the frame lifetime could be exploited "somehow"...

> Or, if tracing should work for all frames, by pushing the original
> in the back of the modified. Both works.

Tracing is done for all frames, if sys_tracefunc is not NULL, which
is a function that usually ends up in the f_trace slot.

>
> ciao - chris

I'm confused. I didn't understand your idea.

-- 
       Vladimir MARANGOZOV          | Vladimir.Marangozov@inrialpes.fr
http://sirac.inrialpes.fr/~marangoz | tel:(+33-4)76615277 fax:76615252