Looking through some of the Django code in authentication forms I noticed the following syntax:
label=_("Username")
Normally I would have just used a pair of quotes around the string. Can someone explain what the underscore and parenthesis around "Username" do?
The _ is the name of a callable (function, callable object). It's usually used for the gettext function, for example in Django:
from django.utils.translation import gettext as _
print _("Hello!") # Will print Hello! if the current language is English
# "Bonjour !" in French
# ¡Holà! in Spanish, etc.
As the doc says:
Python’s standard library gettext module installs
_()into the global namespace, as an alias forgettext(). In Django, we have chosen not to follow this practice, for a couple of reasons:[...]
The underscore character (
_) is used to represent “the previous result” in Python’s interactive shell and doctest tests. Installing a global_()function causes interference. Explicitly importinggettext()as_()avoids this problem.
Even if it's a convention, it may not be the case in your code. But be reassured, 99.9% of the time _ is an alias for gettext :)