[Python-Dev] PyEval_GetFrame() revisited (original) (raw)

Armin Rigo arigo@tunes.org
Sat, 15 Mar 2003 23:33:03 -0800 (PST)

Hello Christian,

On Fri, Mar 14, 2003 at 07:05:05PM +0100, Christian Tismer wrote:

> where the PyEvalGetGLobals is used instead of > tstate->frame->fglobals Ah!! Can it be that PyEvalGetFrame() is just indended to signal to an extension like Psyco that it needs to quickly invent a frame now?

Yes, indeed. This was a very limited hack so that the frame would get the correct locals even in the presence of Psyco. Now I realize that it may have been pointless anyway, if this dummy frame is never really used but for tracebacks.

Maybe an API to manipulate tstate->frame could be useful and really lightweight. Alternatively, we could consider what pyexpat does as a general pattern and have an API for it, e.g.:

PyFrame_Push(PyFrameObject* f) -> pushes 'f' on the frame stack, assert()ing that f->f_back is tstate->frame or pushes a new placeholder frame if 'f' is NULL. This also calls the profile and trace hooks.

PyFrame_Pop() -> pops the frame, calling profile and trace hooks, and recording a traceback if PyErr_Occurred().

and maybe a PyFrame_FromC() function that creates a placeholder with controllable parameters as in pyexpat.c:getcode().

A bient�t,

Armin.