[Distutils] RFC : Version comparison

[Trent Mick]

>> 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 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?


Trent

-- 
Trent Mick
trentm at gmail.com