Internationalization in Sugar
Broad Steps to Internationalize/Localize Your Code
Most of these steps are adapted from the Python i18n with some changes for clarity and accuracy.
Step 1: Instrument all the translatable strings in your source code to use the gettext utility.
To ensure that string output from your activity is correctly translated, you would use the gettext utility. The code below imports gettext, renaming it as '_' for code brevity. Then, whenever there is a string that you want to make sure is translated based on language settings, you simply pass it to the _() function. According to the Python Reference Library, gettext will "return the localized translation of message, based on the current global domain, language, and locale directory."
The code snippet below is part of a larger UI creation routine that creates a sugar.graphics.Notebook object and three pages for that notebook. Each page label should be appropriately translated.
from gettext import gettext as _
...
#Add the pages to the notebook.
top_container.add_page(_('First Page'), first_page)
top_container.add_page(_('Second Page'), second_page)
top_container.add_page(_('Third Page'), third_page)
Step 2: Create a "po" directory within your activity bundle to store some files needed to support translation.
Go in to your activity's source directory and create a new subdirectory called "po". In this directory, create a file called POTFILES.in. In POTFILES.in, your first line should be "encoding: UTF-8". Then, each subsequent line should be the name of a source file in your activity bundle that you want translated.
Below is output from a sample shell session where I carry out all the tasks in this step.
>> ls -l total 292 drwxr-xr-x 2 fanwar fanwar 4096 2008-06-06 16:49 activity -rw-r--r-- 1 fanwar fanwar 3143 2008-07-17 16:20 annotateactivity.py drwxr-xr-x 2 fanwar fanwar 4096 2008-06-26 11:24 icons -rw-r--r-- 1 fanwar fanwar 834 2008-07-02 14:30 setup.py -rw-r--r-- 1 root root 1759 2008-07-17 15:03 TextWidget.py >> mkdir po >> cd po >> emacs POTFILES.in & [1] 7164 >> ls POTFILES.in >> cat POTFILES.in encoding: UTF-8 annotateactivity.py TextWidget.py
How do I ensure that using gettext does not crash my activity, especially when I try to translate more complex string substitution?
Since some strings require variables to be substituted into them, they need to be translated carefully. If they're not translated correctly, trying to do a string substitution can crash your activity.
The code below redefines the _() to use the gettext method only if gettext actually works. If there is an exception, the code will simply return the untranslated string. This ensures that instead of crashing, your activity will simply not translate your string.
#Do the import of the gettext, but do not give it the underscore alias
from gettext import gettext
...
#defensive method against variables not translated correctly
def _(s):
#todo: permanent variable
istrsTest = {}
for i in range (0,4):
istrsTest[str(i)] = str(i)
#try to use gettext. If it fails, then just return the string untranslated.
try:
#test translating the string with many replacements
i = gettext(s)
test = i % istrsTest
print test
except:
#if it doesn't work, revert
i = s
return i
...
#Now we can use the _() function and it should not crash if gettext fails.
substitutionMap = {}
substitutionMap[str(1)] = 'one'
substitutionMap[str(2)] = 'two'
substitutionMap[str(3)] = 'three'
print _("Lets count to three: %(1)s, %(2)s, %(3)s") % substitutionMap