[Python-Dev] Binary Compatibility Issue with Python v2.6.5 and v3.1.2

[Phil Thompson]

On Tue, 20 Apr 2010 21:50:51 +0900, David Cournapeau <cournape at gmail.com>
wrote:
> On Tue, Apr 20, 2010 at 9:19 PM, Phil Thompson
> <phil at riverbankcomputing.com> wrote:
>> When I build my C++ extension on Windows (specifically PyQt with MinGW)
>> against Python v2.6.5 it fails to run under v2.6.4. The same problem
>> exists
>> when building against v3.1.2 and running under v3.1.1.
>>
>> The error message is...
>>
>> ImportError: DLL load failed: The specified procedure could not be
found.
>>
>> ...though I don't know what the procedure is.
>>
>> When built against v2.6.4 it runs fine under all v2.6.x. When built
under
>> v3.1.1 it runs fine under all v3.1.x.
>>
>> I had always assumed that an extension built with vX.Y.Z would always
run
>> under vX.Y.Z-1.
> 
> I don't know how well it is handled in python, but this is extremely
> hard to do in general - you are asking about forward compatibility,
> not backward compatibility.

Yes, I know.

> Is there a reason why you need to do this ? The usual practice is to
> build against the *oldest* compatible version you can, so that it
> remains compatible with everything afterwards,

I'm happy to do that if that is the recommendation, although this is the
first time I've noticed this sort of problem (since v1.5).

Phil