bug#65424: Guix doesn't use positional arguments in translated formatted messages

[Maxime Devos]

Op 21-08-2023 om 16:20 schreef Julien Lepiller:
> Le 21 août 2023 14:09:14 GMT+02:00, Maxime Devos <maximedevos@telenet.be> a 
> écrit :
> > Consider, e.g.,
> >
> > (format #t (G_ "~0@*~a should be set to ~1@*~a instead of ~2@*~a~%") "CC" 
> > "(cc-for-target)" "gcc")
> > ->
> > CC should be set to (cc-for-target) instead of gcc
> >
> > By using positional arguments like this, translators can reorder the sentence 
> > to:
> >
> > (format #t (G_ "It's not ~2@*~a that ~0@*~a should be set to, but ~1@*~a~%") "CC" 
> > (cc-for-target) "gcc"))
> >
> > ~0@*~a should be set to ~1@*~a instead of ~2@*~a~%") "CC" "(cc-for-target)" 
> > "gcc")
> > ->
> > It's not gcc that CC should be set to, but (cc-for-target).
> >
> > CC should be set to (cc-for-target) instead of gcc
> >
> > Such reorderings are occasionally useful, yet AFAIK nowhere (except 
> > po/guix/ta.po, the mcron service and de.po) is this used.
> >
> > Sure, you could as translator add these ~N@* afterwards, but you need to know 
> > that's possible in the first place (and if you know it's possible, you still 
> > need to remember or rediscover what exactly to write), and it would be much 
> > simpler and more discoverable if they were included from the start.  Also, 
> > IIRC, Weblate complains if you add these.
> >
> > p.s.: I'm writing a new linter, this particular example doesn't occur yet in 
> > Guix.
>
> That sounds reasonnabe. The very least we could do is document this syntax in 
> the manual. Weblate would complain indeed, sirce it won't find the same formats 
> in the source and target strings. It might complain about the order too, but 
> that's something we could contribute upstseam if it happens.


Proposed new documentation:

* 22.5.5 Translatable messages

When constructing translatable messages with 'format' (<reference to 
guile manual>), it is important to use positional arguments.  For 
example, instead of writing

  (format #t (G_ "The package '~a' is newer than '~a'.~%")
             '("foo" "bar")),

you should write

  (format #t (G_ "The package '~1@*~a' is newer than '~2@*~a'.~%")
             '("foo" "bar"))

instead.  The reason for this is that when translating between 
languages, the word order sometimes changes.  While a translator could 
manually add the '~N@*' to the translation, it is more straightforward 
to include it in the untranslated message from the beginning.

There is also a technical reason for this: Weblate doesn't cope well 
with the translated message and original message having a different 
number of '~'.

Update the following documentation:

     If there are multiple formatting symbols, make sure to respect the
     order.  Guile does not know in which order you intended the string
     to be read, so it will substitute the symbols in the same order as
     the English sentence.

     As an example, you cannot translate ‘package '~a' has been
     superseded by '~a'’ by ‘'~a' superseeds package '~a'’, because the
     meaning would be reversed.  If FOO is superseded by BAR, the
     translation would read ‘'foo' superseeds package 'bar'’.  To work
     around this problem, it is possible to use more advanced formatting
     to select a given piece of data, instead of following the default
     English order.  *Note (guile)Formatted Output::, for more
     information on formatting in Guile.

--->

     If there are multiple formatting symbols, and positional arguments
     are used, you should be able to reorder the formatting symbols if
     it makes more sense in your language.  The positional information
     tells Guile which formatting symbol needs to be replaced by which
     value.

     If positional arguments aren't used and there are multiple
     formatting symbols, that's a bug, and possibly to translate
     the message properly you may need to report the bug.  The use of
     positional arguments in Guix is fairly new, so you might need
     to report plenty of them!

     As an example, you can translate ‘package '~1@*~a' has been
     superseded by '~2@*~a'’ by ‘'~2@*~a' superseeds package '~1@*~a'’.
     In this example, you recognise the positional arguments by the
     prefixes '~1@*' and '~2@*'.

(To be explicit, the changes are Copyright 2023 Maxime Devos

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