[Python-Dev] sys.implementation

[Eric Snow]

On Wed, May 9, 2012 at 3:57 AM, "Martin v. Löwis" <martin at v.loewis.de> wrote:
> Interesting proposal. I have a number of comments:

Thanks for taking a look, Martin.

> - namespace vs. dictionary. Barry was using it in the form
>  sys.implementation.version. I think this is how it should work,
>  yet the PEP says that sys.implementation is a dictionary, which
>  means that you would need to write
>  sys.implementation['version']
>
>  I think the PEP should be silent on the type of sys.implementation,
>  in particular, it should not mandate that it be a module (else
>  "from sys.implementation import url" ought to work)
>
>  [Update: it seems this is already reflected in the PEP. I wonder
>   where the requirement for "a new type" comes from. I think making
>   it a module should be conforming, even though probably discouraged
>   for cpython, as it would make people think that they can rely on
>   it being a module. I wish there was a builtin class
>
>     class record:
>        pass
>
>   which can be used to create objects which have only attributes
>   and no methods. Making it a type should also work:
>
>    class implementation:
>       name = "cpython"
>       version = (3,3,0)
>
>  in which case it would an instance of an existing type, namely,
>  "type"]

The type for sys.implementation has slowly shifted from the original
proposal.  At this point it's settled into where I think it will stay,
a custom type.  I've covered the choice of type in the rationale
section.  However, there may be merit in not being so specific about
the type.  I'll give that some thought.

> - under-specified attributes: "run-time environment" doesn't mean much
>  to me - my first guess is that it is the set of environment variables,
>  i.e. a dictionary identical to os.environ. I assume you mean something
>  different ...
>  gc_type is supposedly a string, but I cannot guess what possible
>  values it may have. I also wonder why it's relevant.

Sorry for the confusion.  These are from the examples section for
sys.implementation.metadata.  I believe the current version of the PEP
is more clear on the distinction.

Thanks again for the feedback.

-eric