[Zope-CMF] GenericSetup: comparing version numbers

[Maurits van Rees]

Hanno Schlichting, on 2009-11-16:
> On Mon, Nov 16, 2009 at 6:07 PM, Maurits van Rees
><m.van.rees at zestsoftware.nl> wrote:
>> In the metadata.xml in your profile the best practice is currently to
>> use plain version numbers, right?  So just 1, then 2, then 3 etc and
>> not 1.0 then 1.1 then 1.2, right?
>
> Yes.
>
>> Using plain version numbers I have just hit a problem that I find
>> strange that I have not hit before.  An upgrade step from 8 to 9 went
>> fine.  Then I did an upgrade step from 9 to 10 and suddenly
>> portal_setup listed theprevious upgrade step as available, since '10'
>> was alphabetically smaller than '9'...
>>
>> As a workaround I added one or more zeroes to the source, destination
>> and metadata.xml version numbers and then it works. I will hit the
>> next problem after the 99th upgrade step. ;-)
>>
>> Should we change this in GenericSetup itself and add some zeroes in
>> front when comparing numbers?
>
> Which version of GenericSetup was this? In the upcoming 1.5 (Plone
> 4.0) the code uses the pkg_resources API to parse version numbers
> instead of interpreting them as simple strings. That should cover your
> use-case.

Ah, right, this is GS 1.4.5.  And 1.5 does it like this, which works:

>>> from pkg_resources import parse_version
>>> parse_version('9')
('00000009', '*final')
>>> parse_version('10')
('00000010', '*final')
>>> parse_version('9') < parse_version('10')
True

I haven't seen this problem before because I mostly begin counting in
metadata.xml at 100 or 1000.  I guess this is a fine way to avoid this
problem.

-- 
Maurits van Rees | http://maurits.vanrees.org/
            Work | http://zestsoftware.nl/
"This is your day, don't let them take it away." [Barlow Girl]