[Python-Dev] ctypes: is it intentional that id() is the only way to get the address of an object?

[David Mertz]

Oh, bracket my brain glitch on small integers.  Yes, they still give id()
of memory address, they just get reused, which is different.  Nonetheless,
I never teach id(obj)
== ctypes.c_void_p.from_buffer(ctypes.py_object(b)).value ... and not only
because I only learned the latter spelling from eryk sun.

On Fri, Jan 18, 2019 at 10:29 AM David Mertz <mertz at gnosis.cx> wrote:

> On Fri, Jan 18, 2019, 5:55 AM Antoine Pitrou <solipsis at pitrou.net wrote:
>
>>
>> > id() returning the address of the object should be a guaranteed feature
>>
>> For me, the definitive answer is "yes, it's a CPython feature".
>> That doesn't mean the CPython feature has to live forever.  We may want
>> to deprecate it at some point
>
>
> Whenever I've taught Python (quite a bit between writing, in person, and
> webinars), I have been very explicit in stating that id(obj) returns some
> unique number for each object, and mentioned that for MANY Python objects
> CPython users an implementation convenience of using the memory address.
>
> Every time I've explained it I've said not to rely on that implementation
> detail. It's not true for small integers, for example, even in CPython.
>


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