[Python-Dev] a new type for sys.implementation (original) (raw)

Nick Coghlan ncoghlan at gmail.com
Fri Jun 1 14:07:01 CEST 2012

On Fri, Jun 1, 2012 at 9:49 PM, Mark Shannon <mark at hotpy.org> wrote:

What is wrong with something like the following (for CPython)?

class SysImplemention:  "Define repr(), etc here "  ... sys.implementation = SysImplemention() sys.implementation.name = 'cpython' sys.implementation.version = (3, 3, 0, 'alpha', 4) sys.implementation.hexversion = 0x30300a4 sys.implementation.cachetag = 'cpython-33'

Because now you're double keying data in a completely unnecessary fashion. The sys module initialisation code already has access to the info needed to fill out sys.implementation correctly, moving that code somewhere else purely for the sake of getting to write it in Python instead of C would be foolish. Some things are best written in Python, some make sense to write in the underlying implementation language. This is one of the latter because it's all about implementation details.

Also, should the build/machine info be removed from sys.version and moved it to sys.implementation?

No, as the contents of sys.version are already defined as implementation dependent. It remains as the easy to print version, while sys.implementation provides a programmatic interface.

There may be other CPython-specific fields currently in sys.version that it makes sense to also include in sys.implementation, but:

  1. That's as well as, not instead of
  2. It's something that can be looked at after the initial implementation of the PEP has been checked in (and should only be done with a concrete use case, such as eliminating sys.version introspection in other parts of the stdlib or in third party code)

Cheers, Nick.

-- Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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