i18n: factorize "--foo outside a repository"

[alt-git.git] / po / README.md

# Core GIT Translations

This directory holds the translations for the core of Git. This document
describes how you can contribute to the effort of enhancing the language
coverage and maintaining the translation.

The localization (l10n) coordinator, Jiang Xin <worldhello.net@gmail.com>,
coordinates our localization effort in the l10 coordinator repository:

    https://github.com/git-l10n/git-po/

The two character language translation codes are defined by ISO\_639-1, as
stated in the gettext(1) full manual, appendix A.1, Usual Language Codes.


## Contributing to an existing translation

As a contributor for a language XX, you should first check TEAMS file in
this directory to see whether a dedicated repository for your language XX
exists. Fork the dedicated repository and start to work if it exists.

Sometime, contributors may find that the translations of their Git
distributions are quite different with the translations of the
corresponding version from Git official. This is because some Git
distributions (such as from Ubuntu, etc.) have their own l10n workflow.
For this case, wrong translations should be reported and fixed through
their workflows.


## Creating a new language translation

If you are the first contributor for the language XX, please fork this
repository, prepare and/or update the translated message file "po/XX.po"
(described later), and ask the l10n coordinator to pull your work.

If there are multiple contributors for the same language, please first
coordinate among yourselves and nominate the team leader for your
language, so that the l10n coordinator only needs to interact with one
person per language.


## Core translation

The core translation is the smallest set of work that must be completed
for a new language translation. Because there are more than 5000 messages
in the template message file "po/git.pot" that need to be translated,
this is not a piece of cake for the contributor for a new language.

The core template message file which contains a small set of messages
will be generated in "po-core/core.pot" automatically by running a helper
program named "git-po-helper" (described later).

```shell
git-po-helper init --core XX.po
```

After translating the generated "po-core/XX.po", you can merge it to
"po/XX.po" using the following commands:

```shell
msgcat po-core/XX.po po/XX.po -s -o /tmp/XX.po
mv /tmp/XX.po po/XX.po
git-po-helper update XX.po
```

Edit "po/XX.po" by hand to fix "fuzzy" messages, which may have misplaced
translated messages and duplicate messages.


## Translation Process Flow

The overall data-flow looks like this:

    +-------------------+            +------------------+
    | Git source code   | ---(1)---> | L10n coordinator |
    | repository        | <---(4)--- | repository       |
    +-------------------+            +------------------+
                                          |      ^
                                         (2)    (3)
                                          V      |
                                     +------------------+
                                     | Language Team XX |
                                     +------------------+

- Translatable strings are marked in the source file.
- L10n coordinator pulls from the source (1)
- L10n coordinator updates the message template "po/git.pot"
- Language team pulls from L10n coordinator (2)
- Language team updates the message file "po/XX.po"
- L10n coordinator pulls from Language team (3)
- L10n coordinator asks the result to be pulled (4).


## Maintaining the "po/git.pot" file

(This is done by the l10n coordinator).

The "po/git.pot" file contains a message catalog extracted from Git's
sources. The l10n coordinator maintains it by adding new translations with
msginit(1), or update existing ones with msgmerge(1).  In order to update
the Git sources to extract the messages from, the l10n coordinator is
expected to pull from the main git repository at strategic point in
history (e.g. when a major release and release candidates are tagged),
and then run "make pot" at the top-level directory.

Language contributors use this file to prepare translations for their
language, but they are not expected to modify it.


## Initializing a "XX.po" file

(This is done by the language teams).

If your language XX does not have translated message file "po/XX.po" yet,
you add a translation for the first time by running:

```shell
msginit --locale=XX
```

in the "po/" directory, where XX is the locale, e.g. "de", "is", "pt\_BR",
"zh\_CN", etc.

Then edit the automatically generated copyright info in your new "XX.po"
to be correct, e.g. for Icelandic:

```diff
@@ -1,6 +1,6 @@
-# Icelandic translations for PACKAGE package.
-# Copyright (C) 2010 THE PACKAGE'S COPYRIGHT HOLDER
-# This file is distributed under the same license as the PACKAGE package.
+# Icelandic translations for Git.
+# Copyright (C) 2010 Ævar Arnfjörð Bjarmason <avarab@gmail.com>
+# This file is distributed under the same license as the Git package.
 # Ævar Arnfjörð Bjarmason <avarab@gmail.com>, 2010.
```

And change references to PACKAGE VERSION in the PO Header Entry to
just "Git":

```shell
perl -pi -e 's/(?<="Project-Id-Version: )PACKAGE VERSION/Git/' XX.po
```

Once you are done testing the translation (see below), commit the result
and ask the l10n coordinator to pull from you.


## Updating a "XX.po" file

(This is done by the language teams).

If you are replacing translation strings in an existing "XX.po" file to
improve the translation, just edit the file.

If there's an existing "XX.po" file for your language, but the repository
of the l10n coordinator has newer "po/git.pot" file, you would need to first
pull from the l10n coordinator (see the beginning of this document for its
URL), and then update the existing translation by running:

```shell
msgmerge --add-location --backup=off -U XX.po git.pot
```

in the "po/" directory, where "XX.po" is the file you want to update.

Once you are done testing the translation (see below), commit the result
and ask the l10n coordinator to pull from you.


## Fuzzy translation

Fuzzy translation is a translation marked by comment "fuzzy" to let you
know that the translation is out of date because the "msgid" has been
changed. A fuzzy translation will be ignored when compiling using "msgfmt".
Fuzzy translation can be marked by hands, but for most cases they are
marked automatically when running "msgmerge" to update your "XX.po" file.

After fixing the corresponding translation, you must remove the "fuzzy"
tag in the comment.


## Testing your changes

(This is done by the language teams, after creating or updating "XX.po" file).

Before you submit your changes go back to the top-level and do:

```shell
make
```

On systems with GNU gettext (i.e. not Solaris) this will compile your
changed PO file with `msgfmt --check`, the --check option flags many
common errors, e.g. missing printf format strings, or translated
messages that deviate from the originals in whether they begin/end
with a newline or not.


## Marking strings for translation

(This is done by the core developers).

Before strings can be translated they first have to be marked for
translation.

Git uses an internationalization interface that wraps the system's
gettext library, so most of the advice in your gettext documentation
(on GNU systems `info gettext` in a terminal) applies.

General advice:

- Don't mark everything for translation, only strings which will be
  read by humans (the porcelain interface) should be translated.

  The output from Git's plumbing utilities will primarily be read by
  programs and would break scripts under non-C locales if it was
  translated. Plumbing strings should not be translated, since
  they're part of Git's API.

- Adjust the strings so that they're easy to translate. Most of the
  advice in `info '(gettext)Preparing Strings'` applies here.

- If something is unclear or ambiguous you can use a "TRANSLATORS"
  comment to tell the translators what to make of it. These will be
  extracted by xgettext(1) and put in the "po/\*.po" files, e.g. from
  git-am.sh:

  ```shell
  # TRANSLATORS: Make sure to include [y], [n], [e], [v] and [a]
  # in your translation. The program will only accept English
  # input at this point.
  gettext "Apply? [y]es/[n]o/[e]dit/[v]iew patch/[a]ccept all "
  ```

  Or in C, from builtin/revert.c:

  ```c
  /* TRANSLATORS: %s will be "revert" or "cherry-pick" */
  die(_("%s: Unable to write new index file"), action_name(opts));
  ```

We provide wrappers for C, Shell and Perl programs. Here's how they're
used:


### C

Include builtin.h at the top, it'll pull in gettext.h, which
defines the gettext interface. Consult with the list if you need to
use gettext.h directly.

The C interface is a subset of the normal GNU gettext
interface. We currently export these functions:

- \_()

  Mark and translate a string. E.g.:

  ```c
  printf(_("HEAD is now at %s"), hex);
  ```

- Q\_()

  Mark and translate a plural string. E.g.:

  ```c
  printf(Q_("%d commit", "%d commits", number_of_commits));
  ```

  This is just a wrapper for the ngettext() function.

- N\_()

  A no-op pass-through macro for marking strings inside static
  initializations, e.g.:

  ```c
  static const char *reset_type_names[] = {
      N_("mixed"), N_("soft"), N_("hard"), N_("merge"), N_("keep"), NULL
  };
  ```

  And then, later:

  ```c
  die(_("%s reset is not allowed in a bare repository"),
        _(reset_type_names[reset_type]));
  ```

  Here `_()` couldn't have statically determined what the translation
  string will be, but since it was already marked for translation
  with `N_()` the look-up in the message catalog will succeed.


### Shell

The Git gettext shell interface is just a wrapper for
gettext.sh. Import it right after git-sh-setup like this:

```shell
. git-sh-setup
. git-sh-i18n
```

And then use the `gettext` or `eval_gettext` functions:

```shell
# For constant interface messages:
gettext "A message for the user"; echo

# To interpolate variables:
details="oh noes"
eval_gettext "An error occurred: \$details"; echo
```

In addition we have wrappers for messages that end with a trailing
newline. I.e. you could write the above as:

```shell
# For constant interface messages:
gettextln "A message for the user"

# To interpolate variables:
details="oh noes"
eval_gettextln "An error occurred: \$details"
```

More documentation about the interface is available in the GNU info
page: `info '(gettext)sh'`. Looking at git-am.sh (the first shell
command to be translated) for examples is also useful:

```shell
git log --reverse -p --grep=i18n git-am.sh
```


### Perl

The Git::I18N module provides a limited subset of the
Locale::Messages functionality, e.g.:

```perl
use Git::I18N;
print __("Welcome to Git!\n");
printf __("The following error occurred: %s\n"), $error;
```

Run `perldoc perl/Git/I18N.pm` for more info.


## Testing marked strings

Git's tests are run under `LANG=C LC_ALL=C`. So the tests do not need be
changed to account for translations as they're added.


## PO helper

To make the maintenance of "XX.po" easier, the l10n coordinator and l10n
team leaders can use a helper program named "git-po-helper". It is a
wrapper to gettext suite, specifically written for the purpose of Git
l10n workflow.

To build and install the helper program from source, see
[git-po-helper/README][].

Usage for git-po-helper:

- To start a new language translation:

  ```shell
  git-po-helper init XX.po
  ```

- To update your "XX.po" file:

  ```shell
  git-po-helper update XX.po
  ```

- To check commit log and syntax of "XX.po":

  ```shell
  git-po-helper check-po XX.po
  git-po-helper check-commits
  ```

Run "git-po-helper" without arguments to show usage.


## Conventions

There are some conventions that l10n contributors must follow:

- The subject of each l10n commit should be prefixed with "l10n: ".

- Do not use non-ASCII characters in the subject of a commit.

- The length of commit subject (first line of the commit log) should
  be less than 50 characters, and the length of other lines of the
  commit log should be no more than 72 characters.

- Add "Signed-off-by" trailer to your commit log, like other commits
  in Git. You can automatically add the trailer by committing with
  the following command:

  ```shell
  git commit -s
  ```

- Check syntax with "msgfmt" or the following command before creating
  your commit:

  ```shell
  git-po-helper check-po <XX.po>
  ```

- Squash trivial commits to make history clear.

- DO NOT edit files outside "po/" directory.

- Other subsystems ("git-gui", "gitk", and Git itself) have their
  own workflow. See [Documentation/SubmittingPatches][] for
  instructions on how to contribute patches to these subsystems.


To contribute for a new l10n language, contributor should follow
additional conventions:

- Initialize proper filename of the "XX.po" file conforming to
  iso-639 and iso-3166.

- Must complete a minimal translation based on the "po-core/core.pot"
  template. Using the following command to initialize the minimal
  "po-core/XX.po" file:

  ```shell
  git-po-helper init --core <your-language>
  ```

- Add a new entry in the "po/TEAMS" file with proper format, and check
  the syntax of "po/TEAMS" by running the following command:

  ```shell
  git-po-helper team --check
  ```


[git-po-helper/README]: https://github.com/git-l10n/git-po-helper#readme
[Documentation/SubmittingPatches]: Documentation/SubmittingPatches