[Python-Dev] seeing off SET_LINENO

[Guido van Rossum]

> The problem is that when we jump into the epilogue, a 'line' trace
> event gets generated before the 'return' one.  So there is no
> --Return-- hint.

Ah, I missed that detail in your transcript.

> 1) Don't you find the idea of type(co.co_code) == types.ArrayType at
>    least a little scary?  Mainly due to resizes -- having mutable code
>    might be nice for development environments and such.

Yes, it's scary.  But nobody does this, and as you say, it can't be
done from Python.

> 2) I thought it was possible for bf_getreadbuffer to fail (maybe I'm
>    wrong here).  _PyCode_GETCODEPTR does no error checking.

So one should only use objects whose bf_getreadbuffer won't fail (when
invoked with segment index 0).

> > I'd be happy to kill it as a YAGNI.
> 
> That's nice, but if...
> 
> > But that still doesn't mean I approve checking for "4 bytes from the
> > end".
> 
> ...it doesn't actually help.

Well, it kills off a potentially unsafe feature.

> Does anyone have any better ideas for not generating 'line' trace
> events in the epilogue?

Use a separate opcode for which you could check?

--Guido van Rossum (home page: http://www.python.org/~guido/)