[Python-Dev] [2.3a2+] Change in int() behavior

Tim Peters tim.one@comcast.net
Sat, 08 Mar 2003 01:28:54 -0500

[David Abrahams]
> Yes, but in the meantime, PyInt_AS_LONG( invoke_int_conversion(x) )
> might be a crash instead of raising an exception.

As the comment before that macro's definition says,

/* Macro, trading safety for speed */

PyInt_AsLong() won't crash, but its result needs to be checked for an error

Note that your example:

    PyInt_AS_LONG( invoke_int_conversion(x) )

wasn't safe before either:  I'm not sure what invoke_int_conversion(x) means
exactly, but the plausible meanings I can think of for it *could* yield a
NULL pointer, or a pointer to a non-int object, in any version of Python
(e.g., PyNumber_Int() calls tp_as_number->nb_int but doesn't check the
return value for sanity).  In either of those cases PyInt_AS_LONG blindly
applied to the result could crash.

> That's what is causing my test to fail.  I guess I just need to lowercase
> a few characters,

You also need to check for an error return -- PyInt_AsLong() can fail.

> but it's worth noting that this change breaks existing
> extension module code.

I'm not sure it can break any I wouldn't have considered broken before.
It's normal (& expected) not to use the macro unless you *know* you've got
an int object, usually by virtue of passing a PyInt_Check() test first.