NAME
po4a-runtime - po4a and runtime gettext translation without autotools.
Introduction
With po4a-build, po4a also includes support for adding translation of
runtime script output messages using gettext but without requiring the
package to adopt autotools and the typical ./configure process.
Using example Makefile snippets, packages can harness intltool with
minimal effort.
Layout
Documentation translation should NOT use the same po/ directory as the
runtime translation. Whilst runtime translation can use directories
other than po/, it is usually easiest to go with the convention.
Multiple languages
Just a word on packages that use scripts in multiple programming
languages. A common mix is perl and shell. Note bene: gettext WILL get
confused and omit strings from one or other language unless file
extensions are used for whichever is the least problematic language.
When using multiple languages, experiment with various settings in
po/Makevars until you get all the strings you need in the POT file.
In particular, specifying two languages in po/Makevars can be
problematic. Instead of:
# Don't do this:
XGETTEXT_OPTIONS = -L Perl -L Shell --from-code=iso-8859-1
Consider renaming (or providing symlink(s) for) all files for one of
the languages involved and omitting the explicit -L options. The file
extension only needs to exist during the time that po/POTFILES.in is
being processed.
The --keywords option can also be useful - see the xgettext
documentation.
Populating po/
So, create your top level po/ directory and then use the example files
in /usr/share/doc/po4a/examples/ to populate it.
LINGUAS
Must exist, even if empty. Consists of a list of translations -
each line not starting with a '#' must match an existing PO file.
e.g. if LINGUAS contains a single line, 'fr', an fr.po file must
exist alongside the LINGUAS file.
$ cat po/LINGUAS
cs
de
fr
$
By convention, the LINGUAS file is sorted alphabetically but that
is a manual process.
POTFILES.in
The list of files containing the messages that need to be
translated at runtime - i.e. your scripts. If you've used the top
level po/ directory, the paths should be relative to the top level
directory, not the po/ directory itself.
$ ls -l
myscript.pl
another.pl
foo/support.pl
po/
po/POTFILES.in
$ cat po/POTFILES.in
myscript.pl
another.pl
foo/support.pl
$
Note that it is explicitly supported that the scripts themselves
can contain strings for both runtime and documentation translation,
e.g. using gettext functions for runtime and embedded POD content
for documentation. So it is not a problem to have the same file
listed in po/POTFILES.in and doc/po4a-build.conf
Makevars-perl.example
If your scripts are perl, copy this example file as po/Makevars and
edit it to suit.
Makevars-shell.example
If your scripts are shell, copy this example file as po/Makevars
and edit it to suit.
po4a-build.make
Copy this example file as po/Makefile - it shouldn't need editing
but you may want to keep it updated against
/usr/share/doc/po4a/examples/po4a-build.make as it may need to be
updated within po4a releases as the underlying intltool support
changes. (The file itself was generated from another project using
autotools and intltool.)
Building
These snippets need to be added to your top level Makefile or whatever
other method you use to prepare your sources for distribution.
clean:
$(MAKE) -C po/ clean
install:
$(MAKE) -C po/ install DESTDIR=$(DESTDIR)
dist:
$(MAKE) -C po/ pot
(In an autotools project, this would happen automatically by simply
adding po to the "SUBDIRS" value in Makefile.am.)
Maintenance
Runtime translation isn't quite as easy as po4a-build in that adding a
new translation does require editing po/LINGUAS, but apart from that,
updating translations is merely a case of replacing the relevant PO
file with the new version.
Depending on how you prepare your source tarball, you may also need to
list new PO files in the MANIFEST file or add to the script(s) that
prepare the tarball. (That also applies to po4a-build.)
Any *.mo or *.gmo files in po can be deleted / cleaned up.
Copyright
Whilst the example files are part of the po4a project, you are free to
use, modify and distribute them in your own projects without needing to
refer back to po4a or list the po4a team in your own copyright notices,
in the same manner as other build tools like automake itself. If you
want to mention po4a, that is fine too.
AUTHORS
Neil Williams <linux@codehelp.co.uk>