[Python-Dev] Re: tp_clear return value

[Tim Peters]

[Greg Ewing]
> But what about the *visit function*? You need to take
> account of what it might do as well. And if it's ever
> used for something beside GC, it could do anything.

I don't see the relevance.  The visit functions are where the longjmps would
go, if a visit function felt like using one.  Two visit functions in
gcmodule.c would use them, the other visit functions in gcmodule.c would
not.  I don't know of any visit functions not in gcmodule.c (where they all
have static scope), nor do I expect to see any outside of gcmodule.c --
visit functions are Python internals.  tp_clear and tp_traverse functions
must be supplied by extension authors who want their types to play with the
gc system, but extension authors are never required (or even asked) to write
a visit function.