spec: Add support for source locales

[pwithnall]

This allows specifying the locale of the source translatable strings
in a component. The vast majority of the time, this is en_US, but
that’s not guaranteed. Add a source-locale attribute to allow changing
this default.

Signed-off-by: Philip Withnall pwithnall@endlessos.org

Helps: #345

[ximion]

With the tag name style change and the para typo fixed, I think this is fine.
I do wonder though whether we maybe only need source_locale on the translation tag, and, since the language tags are usually auto-generated, could then make the generator code just "do the right thing" and insert a 100% en_US block or whatever source_locale was set to.
Is there any value in knowing the original language in a language tag block?

If we would go with the source_locale property on both translation and languages approach, I wonder if implementation-wise, libappstream should just abstract this away and "do the right thing", that is, add a "100% en_US" or "100% de_DE" entry if source_locale is either of the two. Then, when serializing the XML, it could restore the original source_locale property and drop the extra language value.
Would probably be a bit annoying to implement, but would save all clients from having to deal with this explicitly.

[pwithnall]

With the tag name style change and the para typo fixed, I think this is fine.
I do wonder though whether we maybe only need source_locale on the translation tag, and, since the language tags are usually auto-generated, could then make the generator code just "do the right thing" and insert a 100% en_US block or whatever source_locale was set to.

Sure, I’ve changed the spec wording and changes to go with that.

I’ll start working on the appstream-compose changes for this now, so please shout if something still looks wrong in the spec!

[pwithnall]

I’ll start working on the appstream-compose changes for this now, so please shout if something still looks wrong in the spec!

Done!

[ximion]

Looks good, except for the memory leak ^^
One peculiar thing about libappstream's code is that a lot of it was written without convenience helpers for the XML stuff at first, because adding if (a != NULL) and (xmlChar*) everywhere isn't so bad... you would think, until you have done that a billion times :-P
So, new code should use those helpers, but reading through all the old code to refactor 100% of it to use the new helpers so far wasn't worth the effort. I admit that the current mix is odd for people touching the code initially though.

[pwithnall]

So, new code should use those helpers, but reading through all the old code to refactor 100% of it to use the new helpers so far wasn't worth the effort. I admit that the current mix is odd for people touching the code initially though.

Makes sense. Branch updated :)

[ximion]

Looks good, thank you for working on this! :-)