[Distutils] RFC : Version comparison

[Jean-Paul Calderone]

On Mon, 27 Apr 2009 09:36:24 -0700, Trent Mick <trentm at gmail.com> wrote:
>>> Can a constructor which takes each part of the version data
>>> as a separate object be added?
>>
>> Sounds good, I'd be in favor of making RationalVersion using explicit
>> version bits,
>> and having some kind of function:
>>
>> str2version(somestring) -> RationalVersion instance
>
>Or we could have:
>
>   RationalVersion(...version bits...)
>   RationalVersion.from_string(s)      # this is a @classmethod

I like the sound of that.

>
>> I have pushed the prototype in a bitbucket project so everyone can
>> work it out (just join the project)
>>
>> http://bitbucket.org/tarek/distutilsversion/
>
>Thanks for putting this up.
>
>If we provide a way to construct a RationalVersion with version bits,
>then we need to discuss what those "version bits" look like. Currently
>the internal tuple data structure (`self.info`) looks like this (from
>verlib.py's description of the 'f' marker used to help with sort
>ordering, http://bitbucket.org/tarek/distutilsversion/src/cc93f5e1df3f/verlib.py#cl-163):
>
>    # A marker used in the second and third parts of the `info` tuple, for
>    # versions that don't have those segments, to sort properly. A example
>    # of versions in sort order ('highest' last):
>    #   1.0b1           ((1,0), ('b',1), ('f',))
>    #   1.0.dev345      ((1,0), ('f',),  ('dev', 345))
>    #   1.0             ((1,0), ('f',),  ('f',))
>    #   1.0.post345     ((1,0), ('f',),  ('post', 345))
>    #                           ^        ^
>    #   'f' < 'b' -------------/         |
>    #                                    |
>    #   'dev' < 'f' < 'post' -----------/
>    # Other letters would do, bug 'f' for 'final' is kind of nice.
>
>Is this what we would want the constructor to take?
>
>  RationalVersion( (1,0), ('b', 1) )     # 1.0b1
>  RationalVersion( (1,0), ('f',), ('post', 345) )   # 1.0.post345
>
>It seems a little too low-level. We could allow something a little nicer:
>
>  RationalVersion( (1, 0, 'b', 1) )   # 1.0b1
>  RationalVersion( (1, 0, 'post', 345) ) # 1.0.post345
>
>If we did this, then we'd probably want these attributes on RationalVersion:
>
>>>> v = RationalVersion((1,0,'b',1))
>>>> str(v)
>'1.0b1'
>>>> v.info
>(1, 0, 'b', 1)
>>>> v._cmp_info   # use for comparison
>((1, 0), ('b', 1), ('f',))
>
>
>Thoughts?
>

I'd be in favor of replacing the 'b' and 'post' and so forth with
symbolic constants - eg, RationalVersion((1, 0, RationalVersion.POST, 345)).
If not that, then I'd at least like 'final' instead of 'f', 'beta' instead
of 'b' (is that what 'b' means?) - since this doesn't necessarily need to
be tied to how the version is serialized: it's for programmers to type, so
the more obvious it is what things mean, the better.

Jean-Paul