[Python-Dev] PySet API

Greg Ewing greg.ewing at canterbury.ac.nz
Tue Mar 28 07:28:57 CEST 2006

Barry Warsaw wrote:
> My PySet_Clear() raises a SystemError
> and returns -1 when the object is a frozen set.

Isn't SystemError a bit drastic? TypeError would be
sufficient here, surely.
> If PyObject_Clear() is implemented something like
> int PyObject_Clear(PyObject *o)
> {
>     return (o->ob_type->tp_clear ? o->ob_type->tp_clear(o) : -1);
> }
> then you /would/ be able to clear a frozen set.

Hmmm, the problem here, I think, is that tp_clear is
really only designed for use by the garbage collector.
Giving anything else access to it is probably wrong.

Clearability is not a general feature in Python land --
a few types have a clear() method, but this is an
ad hoc feature of the type concerned. I don't think
it makes sense to have a general PyObject_Clear
function at all.


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