2 language applications

Alex Martelli aleaxit at yahoo.com
Wed Jun 6 11:49:50 CEST 2001

"Cristian Echeverria" <cer at tutopia.com> wrote in message
news:9fk6ll$4ln39$1 at ID-44371.news.dfncis.de...
> Hi
> I have a gui application with all the messages in spanish, now I want to
> include an option that allow the user to choose the language.
> Wich is the right way to do things like this?
> Any suggestion that can help me?
> (I'am using Python2.0 and wxPython 2.3 on win9X)

See standard Python module gettext -- it's part of core
Python so you should have it in any distribution.

The tools to *generate* the needed messagefiles may or
may not be part of your Python distribution -- if you
can't find them, get a Python *source* distribution and
look for Tools/i18n.  (Not sure why this VERY useful
directory is not included in some distributions - it's
just two Python scripts after all!-).

Say I have this big Python application saluta.py...:
print "buon giorno!"
print "ciao!")
print "buona sera!"

First I internationalize it as follows:
import os,gettext


print _("buon giorno!")
print _("ciao!")
print _("buona sera!")

The key thing is marking with _(...) the
strings which ARE to be translated!

Now I can't run it...:

D:\py21>python saluta.py
Traceback (most recent call last):
  File "saluta.py", line 4, in ?
  File "d:\python21\lib\gettext.py", line 251, in install
    translation(domain, localedir).install(unicode)
  File "d:\python21\lib\gettext.py", line 238, in translation
    raise IOError(ENOENT, 'No translation file found for domain', domain)
IOError: [Errno 2] No translation file found for domain: 'saluta'


I have to prepare a message file first...:

D:\py21>python \python-2.1\Tools\i18n\pygettext.py saluta.py

D:\py21>type messages.pot
msgid ""
msgstr ""
"Project-Id-Version: PACKAGE VERSION\n"
"POT-Creation-Date: Wed Jun 06 11:29:12 2001\n"
"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
"Last-Translator: FULL NAME <EMAIL at ADDRESS>\n"
"Language-Team: LANGUAGE <LL at li.org>\n"
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=CHARSET\n"
"Content-Transfer-Encoding: ENCODING\n"
"Generated-By: pygettext.py 1.3\n"

#: saluta.py:5
msgid "buon giorno!"
msgstr ""

#: saluta.py:7
msgid "buona sera!"
msgstr ""

#: saluta.py:6
msgid "ciao!"
msgstr ""


Now I have to edit this textfile to prepare the
needed .po files -- after the beginning metadata
(to be suitably edited), I'll have an it.po something
#: saluta.py:5
msgid "buon giorno!"
msgstr "buon giorno!"

#: saluta.py:7
msgid "buona sera!"
msgstr "buona sera!"

#: saluta.py:6
msgid "ciao!"
msgstr "ciao!"

and an en.po something like:
#: saluta.py:5
msgid "buon giorno!"
msgstr "good morning!"

#: saluta.py:7
msgid "buona sera!"
msgstr "good evening!"

#: saluta.py:6
msgid "ciao!"
msgstr "hello!"

So I compile them:
D:\py21>python \python-2.1\Tools\i18n\msgfmt.py en.po

D:\py21>python \python-2.1\Tools\i18n\msgfmt.py it.po

And prepare the needed directories (lots of intermediate
mkdir's snipped:-):
D:\py21>mkdir \python21\share\locale\it\LC_MESSAGES
D:\py21>mkdir \python21\share\locale\en\LC_MESSAGES

and put the .mo files in the right places:

D:\py21>copy it.mo \python21\share\locale\it\LC_MESSAGES\saluta.mo
        1 file(s) copied.

D:\py21>copy en.mo \python21\share\locale\en\LC_MESSAGES\saluta.mo
        1 file(s) copied.


And NOW it finally runs properly:

D:\py21>python saluta.py
buon giorno!
buona sera!

D:\py21>set LANGUAGE=en

D:\py21>python saluta.py
good morning!
good evening!

I hope this simple toy example helps you get started... it's a
rich and complex system, meant to cover potentially very large
applications with dozens of languages, modules that must not
touch global settings, etc, etc, and it works quite smoothly
over its broad range of applicability, even though it MAY look
like a BIT of an overkill when just looking at one simple case
such as this one!-)


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