Re: [gentoo-dev] [GLEP56] USE flag descriptions in metadata

[Doug Goldstein]

Marius Mauch wrote:
> On Thu, 05 Jun 2008 17:01:00 -0400
> Doug Goldstein <cardoe@g.o> wrote:
>
>
>> Marius Mauch wrote:
>>
>>> On Thu, 05 Jun 2008 15:42:24 -0400
>>> Doug Goldstein <cardoe@g.o> wrote:
>>>
>>>
>>>
>>>> All,
>>>>
>>>> Here's a GLEP for the addition of USE flag descriptions to package
>>>> metadata. It does not address any future ideas that others may have
>>>> had or suggested. It merely gives developers the necessary "tools"
>>>> to document their USE flag usage it better detail on a per package
>>>> basis.
>>>>
>>>> An clearly motivation explanation that I didn't add, which I'm
>>>> going to add once I send this is the fact that as per the QA
>>>> Project, use.local.desc can not contain a USE flag that already
>>>> appears globally in use.desc. This would allow a description for
>>>> that USE flag to be contained in the metadata.
>>>>
>>>> http://www.gentoo.org/proj/en/glep/glep-0056.html
>>>>
>>>> I encourage any and all _technical_ feedback.
>>>>
>>>>
>>> Doesn't include any statement about compability with existing tools
>>> or how it's related to use.local.desc (replacement, extension, ...)
>>>
>>> Marius
>>>
>>>
>> It purposefully does not. XML is an extensible language that allows
>> for this type of expandability. Current tools should be able to
>> validate that adding these tags are valid if they appear in the DTD.
>> However, if those tools do not handle those tags they should not do
>> anything with them, hence the nature of XML.
>>
>
> I was more talking about tools that process use flag information
> (equery, euse, ufed, ...).
>
>
>> The replacement of use.local.desc would necessitate a change to any
>> and all tools which use that file and require them to support the new
>> XML data. This of course introduces a chicken/egg issue. I have
>> mentioned to infra the possibility of having a pre-rsync process that
>> condensed all metadata.xml's into a use.local.desc that would be part
>> of rsync data but not part of CVS. This could be written as a CVS
>> hook to see when a metadata.xml was touched and run the utility
>> appropriately.
>>
>> But again, this is outside the scope of this GLEP, whose purpose
>> merely is to provide a way to document this.
>>
>
> I disagree. At the very least state that the GLEP does not replace
> use.local.desc if that's the intention, and which location is
> supposed to take priority if a flag is defined in both. Otherwise
> different tools will use different rules and generating inconsistent
> results. And there are many tools affected by this ...
>
> Marius
>
> PS: I like the general idea, but as long as compability issues are
> completely ignored by the GLEP I have to oppose it.
>
Considering Portage and repoman currently require any and all USE flags 
appearing in IUSE to be present in use.local.desc, there should be no 
ambiguity to the compatibility issues currently. I 100% expect different 
tools to provide different results. Writing a GLEP stating that one file 
is preferred over another will not cause those tools to magically 
choose. The tools and their maintainers should be pushed by the 
community to use the best data available. If use.local.desc provides 
this data, then so be it. The initial goal of this GLEP is really to 
allow per-package descriptions of global USE flags [*]. There by 
different tools will provide more detailed information about USE flags 
and some will simply not. That will result in a community push to make 
these tools use newer data available and as such will result in one day 
use.local.desc becoming deprecated. But, we're speaking about something 
which may never happen. Or may happen in another GLEP in the future.

[*] As decided by the Gentoo QA Team, any USE flag that appears in 
use.desc CAN NOT appear in use.local.desc. There by, there is no way for 
a descriptive variation of a global USE flag to officially appear in any 
medium.
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