To kick things off: what exactly does “gettext” mean? Well, in the world of software localization (which is fancy talk for making your code speak different languages), gettext refers to a set of tools that allow you to extract translatable strings from your source code and store them in separate files called .mo files. These files can then be used by translation teams to translate those strings into other languages, without having to modify the original code.
Now, how Python 3’s gettext function fits into this picture. Essentially, it provides a way for you to access these translatable strings from within your Python code, using a simple syntax that looks like this:
# Import the gettext module
import gettext
# Install the translation for the application or module
gettext.install('myapp') # replace 'myapp' with the name of your application or module
# Create a translation object for the specified domain, with fallback enabled
_ = gettext.translation('myapp', fallback=True)
# Use the translation object to access the translated string
print(_("Hello, world!")) # the _() function is used to mark the string for translation
# Output: Hello, world!
# Explanation:
# The gettext module is imported to access the translation functionality.
# The install() function is used to set up the translation for the specified domain.
# The translation object is created using the translation() function, with fallback enabled to ensure the original string is used if no translation is available.
# The _() function is used to mark the string for translation, and the translated string is accessed using the print statement.
In this example, we first import the `gettext` module and call its `install()` function to register our application (or module) with the translation system. We then create a new instance of the `translation()` class using the name of our application or module as the domain. Finally, we assign that instance to a variable called `_`, which is a common convention for accessing translatable strings in Python code.
Now, let’s break down what each part of this syntax does:
– The `gettext` function imports the gettext module from Python 3’s standard library.
– The `install()` function registers our application or module with the translation system. This is an important step that allows us to access translatable strings using the `_()` function later on.
– We create a new instance of the `translation()` class, passing in two arguments: the name of our domain (which should match the name we used when registering our application or module), and a boolean flag called `fallback`. This flag tells Python to fall back to using the original string if no translation is available.
– Finally, we assign that instance to a variable called `_`, which is a common convention for accessing translatable strings in Python code.
And there you have it a simple and straightforward way to use gettext with Python 3! Of course, this is just the tip of the iceberg when it comes to localization and translation, but hopefully this guide has given you a good starting point.
But wait, what about those ***** .mo files? How do we create them in the first place? Well, that’s where Python 3’s `xgettext` tool comes into play. This handy utility allows us to extract translatable strings from our source code and generate a set of .pot (Portable Object Template) files, which can then be used by translation teams to create their own .po (Portable Object) files for each language they support.
To use `xgettext`, simply run the following command in your terminal:
bash
# This script uses the `gettext` module in Python to extract translatable strings from a source code file and generate a .pot file.
# The .pot file can then be used by translation teams to create .po files for each language they support.
# To use `xgettext`, simply run the following command in your terminal:
# python3 -m gettext.tools xgettext --output=messages.pot myapp/myfile.py
# The `python3` command is used to run the `gettext` module in Python version 3.
# The `-m` flag specifies that the module to be run is `gettext.tools`.
# The `xgettext` command is used to extract translatable strings from the source code.
# The `--output` flag specifies the name of the output file, in this case `messages.pot`.
# The `myapp/myfile.py` argument specifies the path to the source code file to be scanned for translatable strings.
In this example, we’re using Python 3 to invoke the `xgettext` tool and passing it a few arguments:
– The `–output` flag tells `xgettext` where to save our .pot file (in this case, messages.pot).
– We then specify the name of our application or module (myapp) followed by the path to one of its Python files (myfile.py), which contains translatable strings we want to extract.
Once `xgettext` has finished running, you’ll have a new .pot file that looks something like this:
# This is an ini script that extracts translatable strings from a Python file using xgettext.
# We start by specifying the name of our application or module (myapp) followed by the path to one of its Python files (myfile.py), which contains translatable strings we want to extract.
[myapp:myfile.py]
# We then specify the location of the .pot file where the extracted strings will be saved.
output = messages.pot
# Once xgettext has finished running, a new .pot file will be created with the extracted strings.
# The following code segment shows an example of a .pot file with a single extracted string.
#: myapp/myfile.py:12
msgid "Hello, world!"
msgstr "" # The msgstr field is left empty for translators to fill in the translated string.
This line tells us that the string “Hello, world!” appears on line 12 of our Python code (in `myfile.py`) and currently has no translation available. The empty `msgstr` field is where translators will add their own translations for each language they support.
To create a new .po file for a specific language, simply copy the contents of your .pot file into a new .po file with the appropriate language code (e.g., messages_fr.po for French). Then replace all instances of `msgstr “”` with the translated string in that language:
# This script is used to create a new .po file for a specific language by copying the contents of a .pot file and replacing the empty translated strings with the translated string in that language.
# The following line specifies the file and line number where the original string is located.
#: myapp/myfile.py:12
# The following line contains the original string to be translated.
msgid "Hello, world!"
# The following line contains the translated string in French.
msgstr "Bonjour le monde !"
And there you have it a simple and straightforward way to use gettext with Python 3! Of course, this is just the tip of the iceberg when it comes to localization and translation, but hopefully this guide has given you a good starting point.