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# Authors: # Jason Gerard DeRose <jderose@redhat.com> # # Copyright (C) 2009 Red Hat # see file 'COPYING' for use and warranty contextrmation # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation, either version 3 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program. If not, see <http://www.gnu.org/licenses/>.
Defers gettext translation till request time.
IPA presents some tricky gettext challenges. On the one hand, most translatable message are defined as class attributes on the plugins, which means these get evaluated at module-load time. But on the other hand, each request to the server can be in a different locale, so the actual translation must not occur till request time.
The `text` module provides a mechanism for for deferred gettext translation. It was designed to:
1. Allow translatable strings to be marked with the usual ``_()`` and ``ngettext()`` functions so that standard tools like xgettext can still be used
2. Allow programmers to mark strings in a natural way without burdening them with details of the deferred translation mechanism
A typical plugin will use the deferred translation like this:
>>> from ipalib import Command, _, ngettext >>> class my_plugin(Command): ... my_string = _('Hello, %(name)s.') ... my_plural = ngettext('%(count)d goose', '%(count)d geese', 0) ...
With normal gettext usage, the *my_string* and *my_plural* message would be translated at module-load-time when your ``my_plugin`` class is defined. This would mean that all message are translated in the locale of the server rather than the locale of the request.
However, the ``_()`` function above is actually a `GettextFactory` instance, which when called returns a `Gettext` instance. A `Gettext` instance stores the message to be translated, and the gettext domain and localedir, but it doesn't perform the translation till `Gettext.__unicode__()` is called. For example:
>>> my_plugin.my_string Gettext('Hello, %(name)s.', domain='ipa', localedir=None) >>> unicode(my_plugin.my_string) u'Hello, %(name)s.'
Translation can also be performed via the `Gettext.__mod__()` convenience method. For example, these two are equivalent:
>>> my_plugin.my_string % dict(name='Joe') u'Hello, Joe.' >>> unicode(my_plugin.my_string) % dict(name='Joe') # Long form u'Hello, Joe.'
Similar to ``_()``, the ``ngettext()`` function above is actually an `NGettextFactory` instance, which when called returns an `NGettext` instance. An `NGettext` instance stores the singular and plural messages, and the gettext domain and localedir, but it doesn't perform the translation till `NGettext.__call__()` is called. For example:
>>> my_plugin.my_plural NGettext('%(count)d goose', '%(count)d geese', domain='ipa', localedir=None) >>> my_plugin.my_plural(1) u'%(count)d goose' >>> my_plugin.my_plural(2) u'%(count)d geese'
Translation can also be performed via the `NGettext.__mod__()` convenience method. For example, these two are equivalent:
>>> my_plugin.my_plural % dict(count=1) u'1 goose' >>> my_plugin.my_plural(1) % dict(count=1) # Long form u'1 goose'
Lastly, 3rd-party plugins can create factories bound to a different gettext domain. The default domain is ``'ipa'``, which is also the domain of the standard ``ipalib._()`` and ``ipalib.ngettext()`` factories. But 3rd-party plugins can create their own factories like this:
>>> from ipalib import GettextFactory, NGettextFactory >>> _ = GettextFactory(domain='ipa_foo') >>> ngettext = NGettextFactory(domain='ipa_foo') >>> class foo(Command): ... msg1 = _('Foo!') ... msg2 = ngettext('%(count)d bar', '%(count)d bars', 0) ...
Notice that these messages are bound to the ``'ipa_foo'`` domain:
>>> foo.msg1 Gettext('Foo!', domain='ipa_foo', localedir=None) >>> foo.msg2 NGettext('%(count)d bar', '%(count)d bars', domain='ipa_foo', localedir=None)
For additional details, see `GettextFactory` and `Gettext`, and for plural forms, see `NGettextFactory` and `NGettext`. """
localedir=localedir, languages=getattr(context, 'languages', None), fallback=True, )
""" Base class for deferred translation.
This class is not used directly. See the `Gettext` and `NGettext` subclasses. """
""" Initialize.
:param domain: The gettext domain in which this message will be translated, e.g. ``'ipa'`` or ``'ipa_3rd_party'``; default is ``None`` :param localedir: The directory containing the gettext translations, e.g. ``'/usr/share/locale/'``; default is ``None``, in which case gettext will use the default system locale directory. """
""" Return ``True`` if this instances is equal to *other*.
Note that this method cannot be used on the `LazyText` base class itself as subclasses must define an *args* instance attribute. """ return False
""" Return ``True`` if this instances is not equal to *other*.
Note that this method cannot be used on the `LazyText` base class itself as subclasses must define an *args* instance attribute. """
""" Deferred translation using ``gettext.ugettext()``.
Normally the `Gettext` class isn't used directly and instead is created via a `GettextFactory` instance. However, for illustration, we can create one like this:
>>> msg = Gettext('Hello, %(name)s.')
When you create a `Gettext` instance, the message is stored on the *msg* attribute:
>>> msg.msg 'Hello, %(name)s.'
No translation is performed till `Gettext.__unicode__()` is called. This will translate *msg* using ``gettext.ugettext()``, which will return the translated string as a Python ``unicode`` instance. For example:
>>> unicode(msg) u'Hello, %(name)s.'
`Gettext.__unicode__()` should be called at request time, which in a nutshell means it should be called from within your plugin's ``Command.execute()`` method. `Gettext.__unicode__()` will perform the translation based on the locale of the current request.
`Gettext.__mod__()` is a convenience method for Python "percent" string formatting. It will translate your message using `Gettext.__unicode__()` and then perform the string substitution on the translated message. For example, these two are equivalent:
>>> msg % dict(name='Joe') u'Hello, Joe.' >>> unicode(msg) % dict(name='Joe') # Long form u'Hello, Joe.'
See `GettextFactory` for additional details. If you need to pick between singular and plural form, use `NGettext` instances via the `NGettextFactory`. """
self.msg, self.domain, self.localedir)
""" Translate this message and return as a ``unicode`` instance. """ else:
return self.__unicode__()
""" Non-translated place-holder for UI labels.
`FixMe` is a subclass of `Gettext` and is used for automatically created place-holder labels. It generally behaves exactly like `Gettext` except no translation is ever performed.
`FixMe` allows programmers to get plugins working without first filling in all the labels that will ultimately be required, while at the same time it creates conspicuous looking UI labels that remind the programmer to "fix-me!". For example, the typical usage would be something like this:
>>> class Plugin(object): ... label = None ... def __init__(self): ... self.name = self.__class__.__name__ ... if self.label is None: ... self.label = FixMe(self.name + '.label') ... assert isinstance(self.label, Gettext) ... >>> class user(Plugin): ... pass # Oops, we didn't set user.label yet ... >>> u = user() >>> u.label FixMe('user.label')
Note that as `FixMe` is a subclass of `Gettext`, is passes the above type check using ``isinstance()``.
Calling `FixMe.__unicode__()` performs no translation, but instead returns said conspicuous looking label:
>>> unicode(u.label) u'<user.label>'
For more examples of how `FixMe` is used, see `ipalib.parameters`. """
""" Deferred translation for plural forms using ``gettext.ungettext()``.
Normally the `NGettext` class isn't used directly and instead is created via a `NGettextFactory` instance. However, for illustration, we can create one like this:
>>> msg = NGettext('%(count)d goose', '%(count)d geese')
When you create an `NGettext` instance, the singular and plural forms of your message are stored on the *singular* and *plural* instance attributes:
>>> msg.singular '%(count)d goose' >>> msg.plural '%(count)d geese'
The translation and number selection isn't performed till `NGettext.__call__()` is called. This will translate and pick the correct number using ``gettext.ungettext()``. As a callable, an `NGettext` instance takes a single argument, an integer specifying the count. For example:
>>> msg(0) u'%(count)d geese' >>> msg(1) u'%(count)d goose' >>> msg(2) u'%(count)d geese'
`NGettext.__mod__()` is a convenience method for Python "percent" string formatting. It can only be used if your substitution ``dict`` contains the count in a ``'count'`` item. For example:
>>> msg % dict(count=0) u'0 geese' >>> msg % dict(count=1) u'1 goose' >>> msg % dict(count=2) u'2 geese'
Alternatively, these longer forms have the same effect as the three examples above:
>>> msg(0) % dict(count=0) u'0 geese' >>> msg(1) % dict(count=1) u'1 goose' >>> msg(2) % dict(count=2) u'2 geese'
A ``KeyError`` is raised if your substitution ``dict`` doesn't have a ``'count'`` item. For example:
>>> msg2 = NGettext('%(num)d goose', '%(num)d geese') >>> msg2 % dict(num=0) Traceback (most recent call last): ... KeyError: 'count'
However, in this case you can still use the longer, explicit form for string substitution:
>>> msg2(0) % dict(num=0) u'0 geese'
See `NGettextFactory` for additional details. """
self.singular, self.plural, self.domain, self.localedir)
else:
""" Factory for creating ``_()`` functions.
A `GettextFactory` allows you to mark translatable messages that are evaluated at initialization time, but deferred their actual translation till request time.
When you create a `GettextFactory` you can provide a specific gettext *domain* and *localedir*. By default the *domain* will be ``'ipa'`` and the *localedir* will be ``None``. Both are available via instance attributes of the same name. For example:
>>> _ = GettextFactory() >>> _.domain 'ipa' >>> _.localedir is None True
When the *localedir* is ``None``, gettext will use the default system localedir (typically ``'/usr/share/locale/'``). In general, you should **not** provide a *localedir*... it is intended only to support in-tree testing.
Third party plugins will most likely want to use a different gettext *domain*. For example:
>>> _ = GettextFactory(domain='ipa_3rd_party') >>> _.domain 'ipa_3rd_party'
When you call your `GettextFactory` instance, it will return a `Gettext` instance associated with the same *domain* and *localedir*. For example:
>>> my_msg = _('Hello world') >>> my_msg.domain 'ipa_3rd_party' >>> my_msg.localedir is None True
The message isn't translated till `Gettext.__unicode__()` is called, which should be done during each request. See the `Gettext` class for additional details. """
""" Initialize.
:param domain: The gettext domain in which this message will be translated, e.g. ``'ipa'`` or ``'ipa_3rd_party'``; default is ``'ipa'`` :param localedir: The directory containing the gettext translations, e.g. ``'/usr/share/locale/'``; default is ``None``, in which case gettext will use the default system locale directory. """
self.domain, self.localedir)
""" Factory for creating ``ngettext()`` functions.
`NGettextFactory` is similar to `GettextFactory`, except `NGettextFactory` is for plural forms.
So that standard tools like xgettext can find your plural forms, you should reference your `NGettextFactory` instance using a variable named *ngettext*. For example:
>>> ngettext = NGettextFactory() >>> ngettext NGettextFactory(domain='ipa', localedir=None)
When you call your `NGettextFactory` instance to create a deferred translation, you provide the *singular* message, the *plural* message, and a dummy *count*. An `NGettext` instance will be returned. For example:
>>> my_msg = ngettext('%(count)d goose', '%(count)d geese', 0) >>> my_msg NGettext('%(count)d goose', '%(count)d geese', domain='ipa', localedir=None)
The *count* is ignored (because the translation is deferred), but you should still provide it so parsing tools aren't confused. For consistency, it is recommended to always provide ``0`` for the *count*.
See `NGettext` for details on how the deferred translation is later performed. See `GettextFactory` for details on setting a different gettext *domain* (likely needed for 3rd-party plugins). """
# Process wide factories: |