[Python-Dev] That depends on what the meaning of "is" is (was Re: http://mail.python.org/pipermail/python-dev/2011-December/115172.html)

[Jim Jewett]

On Mon, Jan 2, 2012 at 1:16 AM, PJ Eby <pje at telecommunity.com> wrote:
> On Sun, Jan 1, 2012 at 10:28 PM, Jim Jewett <jimjjewett at gmail.com> wrote:
>>
>> Given the wording requiring a real dictionary, I would have assumed
>> that it was OK (if perhaps not sensible) to do pointer arithmetic and
>> access the keys/values/hashes directly.  (Though if the breakage was
>> between python versions, I would feel guilty about griping too
>> loudly.)

> If you're going to be a language lawyer about it, I would simply point out
> that all the spec requires is that "type(env) is dict" -- it says nothing
> about how Python defines "type" or "is" or "dict".  So, you're on your own
> with that one. ;-)

But the public header file <
http://hg.python.org/cpython/file/3ed5a6030c9b/Include/dictobject.h >
defines the typedef structs for PyDictEntry and _dictobject.

What is the purpose of the requiring a "real dict" without also
promising what the header file promises?

-jJ