Localization guidelines

This document provides some guidelines for programmers write user messages. To help translations, user messages must be uniformized. Follow these rules when coding for LilyPond. Hopefully, this can be replaced by general GNU guidelines in the future. Even better would be to have an English (en_BR, en_AM) helping programmers writing consistent messages for all GNU programs.

Not-preferred messages are marked with `+'. By convention, ungrammatical examples are marked with `*'.

Every message to the user should be localised (and thus be marked for localisation). This includes warning and error messages.
Don't localise/gettextify:
- `programming_error ()'s

- `programming_warning ()'s

- debug strings

- output strings (PostScript, TeX, etc.)
Messages to be localised must be encapsulated in `_ (STRING)' or `_f (FORMAT, ...)'. Eg:
```
      warning (_ ("need music in a score"));
      error (_f ("cannot open file: `%s'", file_name));
    
```
In some rare cases you may need to call `gettext ()' by hand. This happens when you pre-define (a list of) string constants for later use. In that case, you'll probably also need to mark these string constants for translation, using `_i (STRING)'. The `_i' macro is a no-op, it only serves as a marker for `xgettext'.
```
      char const* messages[] = {
      _i ("enable debugging output"),
      _i ("ignore lilypond version"),
      0
      };

    
```
```
      void
      foo (int i)
      {
      puts (gettext (messages i));
      }
    
```
See also `flower/getopt-long.cc' and `lily/main.cc'.
Do not use leading or trailing whitespace in messages. If you need whitespace to be printed, prepend or append it to the translated message
```
      message (Calculating line breaks... + " ");
    
```
Error or warning messages displayed with a file name and line number never start with a capital, eg,
```
	foo.ly: 12: not a duration: 3
      
```
Messages containing a final verb, or a gerund (`-ing'-form) always start with a capital. Other (simpler) messages start with a lowercase letter
```
      Processing foo.ly...
      `foo': not declared.
      Not declaring: `foo'.
    
```
Avoid abbreviations or short forms, use `cannot' and `do not' rather than `can't' or `don't'
To avoid having a number of different messages for the same situation, we'll use quoting like this `"message: `%s'"' for all strings. Numbers are not quoted:
```
      _f ("cannot open file: `%s'", name_str)
      _f ("cannot find character number: %d", i)
    
```
Think about translation issues. In a lot of cases, it is better to translate a whole message. The english grammar mustn't be imposed on the translator. So, instead of
```
      stem at  + moment.str () +  does not fit in beam
    
```
have
```
      _f ("stem at %s does not fit in beam", moment.str ())
    
```

Split up multi-sentence messages, whenever possible. Instead of

      warning (_f ("out of tune!  Can't find: `%s'", "Key_engraver"));
      warning (_f ("cannot find font `%s', loading default",
      font_name));

rather say:

      warning (out of tune:;
      warning (_f ("cannot find: `%s', "Key_engraver"));
      warning (_f ("cannot find font: `%s', font_name));
      warning (_f ("Loading default font"));

If you must have multiple-sentence messages, use full punctuation.

Use two spaces after end of sentence punctuation. No punctuation (esp. period) is used at the end of simple messages.

      _f ("Non-matching braces in text `%s', adding braces", text)
      Debug output disabled.  Compiled with NPRINT.
      _f ("Huh?  Not a Request: `%s'.  Ignoring.", request)

Do not modularise too much; a lot of words cannot be translated without context. It's probably safe to treat most occurences of words like stem, beam, crescendo as separately translatable words.
When translating, it is preferable to put interesting information at the end of the message, rather than embedded in the middle. This especially applies to frequently used messages, even if this would mean sacrificing a bit of eloquency. This holds for original messages too, of course.
```
      en: cannot open: `foo.ly'
      +   nl: kan `foo.ly' niet openen (1)
      kan niet openen: `foo.ly'*   (2)
      niet te openen: `foo.ly'*    (3)

    
```
The first nl message, although grammatically and stylistically correct, is not friendly for parsing by humans (even if they speak dutch). I guess we'd prefer something like (2) or (3).
Do not run make po/po-update with GNU gettext < 0.10.35