[Python-Dev] a new type for sys.implementation

[Eric Snow]

On Thu, May 31, 2012 at 9:08 PM, Barry Warsaw <barry at python.org> wrote:
> On Jun 01, 2012, at 11:49 PM, Nick Coghlan wrote:
>
>>The long term goal here is that all the code in the standard library
>>should be implementation independent - PyPy, Jython, IronPython, et al
>>should be able to grab it and just run it. That means the
>>implementation specific stuff needs to migrate into the C code and get
>>exposed through standard APIs. PEP 421 is one step along that road.
>
> Exactly.  Or to put it another way, if you implemented sys.implementation in
> some stdlib Python module, you wouldn't be able to share that module between
> the various Python implementations.  I think the stdlib should strive for
> *more* commonality across Python implementations, not less.  Yes, you could
> conditionalize your way around that, but why do it when writing the code in
> the interpreter implementation language is easy enough?  Plus, who wants to
> maintain the ugly mass of if-statements that would probably require?

Not only that, but any new/experimental/etc. implementation would
either have be blessed in that module by Python committers (a la the
platform module*) or would have to use a fork of the standard library.

* I don't mean to put down the platform module, with has and will
continue to serve us well.  Rather, just pointing out that a small
part of it demonstrates a limitation in the stdlib relative to
alternate implementations.

>
> Eric's C code is easily auditable to anyone who knows the C API well enough,
> and I can't imagine it wouldn't be pretty trivial to write it in Java,
> RPython, or C#.

And I'm by no means a C veteran.  :)

-eric