[Cython] ANN: Pyrex 0.9.7

[Stefan Behnel]

Hi,

Greg Ewing wrote:
> Stefan Behnel wrote:
> 
>> Greg Ewing wrote:
>>
>>> There's no run-time
>>> distinction between a builtin class, an extension class
>>> implemented with Pyrex, or an extension class created some
>>> other way.
>>
>> I didn't mean at runtime. The compiler knows how to distinguish them.
> 
> Well, there's no compile-time distinction either, really.
> They're all the same thing. Treating a type differently
> depending on whether it was implemented using a Pyrex
> extension class would be bizarre and confusing.

Why? If the docs stated "explicitly testing isinstance(obj, ExtType) for a
Pyrex extension type will make sure it's really that specific type with the
expected field structure", then that's just another Pyrex/Cython specific
enhancement that deals with the grey area between Python and C, and that most
(should I say all?) users would expect anyway when calling isinstance(). This
does in no way interfere with Python semantics, as testing for (non-cdefed)
Python types will not imply a specific struct layout anyway.

Make it a feature: tell people that they can assert the C type structure by
calling isinstance(obj, MyExtType) explicitly, and that all other calls will
use the normal Python semantics.

Then, you could still use the following to do a non-explicit test:

>>     allowed_type = ExtType
>>     print isinstance(obj, allowed_type) # Python semantics

This could even become an example in the docs, right next to the paragraph
that explains the lack of "security" in the Python semantics.


> I'm not going to be changing
> my own test setup, so you're not going to be able to share
> any new tests that I add without converting them to your
> format.

Ok, then we'll continue to do that.

Stefan