Re: Converting PyPI to feeds

On 10 March 2017 at 16:21, Tim Diels <[email protected]> wrote:
> I figured out that versions are lists of lists and thus 1 < 1.0 because [1]
> < [1, 0]. So, I don't see a way of converting Python version specifiers to
> Zero Install constraints, due to the lack of zero padding in the dotted
> lists of versions.
>
> One workaround is to pad the versions with zeros according to the longest
> version of the package to convert (E.g. a package with versions 1, 2.2,
> 3.3.3 will zero pad versions to match num.num.num). When, later, a component
> (referring to a '.num') is added, all versions will need to be changed to
> increase padding by one component (E.g. when adding 4.4.4.4). Version
> contraints will need to be padded as well (e.g. ==1 becomes ==1.0.0.0), so
> when a component is added, all constraints need to be updated as well. A
> feed can be required by a feed outside the pypi_to_zi project and thus that
> feed would break when a version component is added. So, this workaround is
> not really an option.

Or, you could strip trailing zeros, so 3.0.0 becomes 3.

> So how could we make this work? It appears it is needed to either:
>
> - change the versioning scheme to add zero padding
> - or support multiple versioning schemes. E.g. like one of these approaches:
>
>   <implementation version='pep440:1.0>
>   <implementation version='1.0' version_scheme='pep440'>
>   <interface><versioning_scheme>pep440  <!-- or only at interface level, as
> you might not want to support using multiple versioning schemes in the same
> interface -->
>
> Cheers,
> Tim
>
> On 9 March 2017 at 18:52, Tim Diels <[email protected]> wrote:
>>
>> Dear Thomas, all,
>>
>> I need input on these problems encountered while converting Python version
>> specifiers to ZI constraints:
>>
>> 1. in Zero Install, version 1 < 1.0 < 1.0.0. In Python, version 1 == 1.0
>> == 1.0.0. E.g. the specifier '==1' would have to be converted to constraint
>> '1..1.0.0.0...' (infinite zeros). Also, how do 1.0.0 and 1.1 compare in Zero
>> Install? Should 1 be interpreted as 1.(-1) perhaps?
>> 2. <version after=... not-after=...> will need to be implemented. Or
>> `version=` should support an & operator for intersection. This is to support
>> '<=version' for example.
>>
>> Thanks,
>> Cheers,
>> Tim
>
>
>
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