[Distutils] [RFC] PEP 345 and PEP 386 updates

[Tarek Ziadé]

On Wed, Oct 21, 2009 at 10:42 AM, M.-A. Lemburg <mal at egenix.com> wrote:
> Tarek Ziadé wrote:
>> On Tue, Oct 20, 2009 at 5:20 PM, M.-A. Lemburg <mal at egenix.com> wrote:
>>>>> The micro-language should provide a limited number of
>>>>> variables to use on the conditions:
>>>>>
>>>>> python_version = sys.version
>>>>> sys_platform = sys.platform
>>>>
>>>> If we adopt such a micro-language (I'm reserving judgment until I've
>>>> had more time to read the relevant PEPs carefully), I'd rather see the
>>>> names match what's in the Python runtime more closely, probably only
>>>> avoiding the call syntax.
>>>
>>> We could do that as well, yes.
>>
>> +1 on close names + no call syntax
>>
>> but, notice that "python_version" here is:   "%s.%s" %
>> sys.version_info[0], sys.version_info[1]
>>
>> thats why we came up with that name, to disinguish it from sys.version
>> (that contains more stuff)
>
> I think we do need the full version here, so perhaps using
> sys.version.split()[0] would be better or simply the full
> version string and then have conditions use >=, <=, <, >
> only (ie. not =, since that would likely never match).

Notice that for the comparisons >, < to work, that requires more than string
comparisons in case we provide the ability to work with rc versions, because:

>>> '2.6.3rc4' < '2.6.3'
False

We said earlier that we could use sys.hexversion to handle this, but otherwise,
at least for the Python version, we can use the StrictVersion() class
from Distutils,

*But* we ended up thinking that it would be better for the first version to keep
just "==", "!=", "in" and "not in" operators and a MAJOR.MINOR string.

These are enough just to compare strings, on a limited number of
versions for Python.

What use case you have in mind for a three numbers version ?

>
> Note that packages do sometimes need to know that a certain
> Python patch level release is installed (e.g. Zope often has
> had this need) and a proper dependency checker would have to
> detect a possible mismatch.

I see. I would rather have this patch info in another variable, and restrict
the micro language capabilities as much as possible.

Any hint were Zope does this ?

Regards
Tarek