[Python-Dev] sizeof(long) != sizeof(void*)

[Martin v. Löwis]

Samuele Pedroni <pedronis at bluewin.ch> writes:

> but that something like id() can be cheaply offered/exposed is very
> much a characteristic of the underlying GC implementation that is
> being exploited (objects don't move)

That is not true. id() exposes the "identity" of an object, and an
run-time system that has the notion of object identities (as opposed
to all-things-with-equal-values-are-equal) should have no difficulties
exposing the object identity as a number.

> I have just gone through implementing a correct id() for Jython.

It sounds like you haven't been looking hard enough. The Java VM
certainly has a unique (among "life" objects) identification of
objects, which likely also fits into a fixed number of bytes.

Interpret these bytes as a number.

Regards,
Martin