Question

I am studying web2py. I read example open source code. In one application (storpy), the programmer uses T.lazy repeatedly inside the models file db.py such as this:

...
Field('comment', 'text'),
Field('cover', 'upload', autodelete=True))

T.lazy = False
db.dvds.title.requires = [IS_NOT_EMPTY(error_message=T('Missing data') + '!'), IS_NOT_IN_DB(db, 'dvds.title', error_message=T('Already in the database') + '!')]
...
T.lazy = True

Why does the programmer set T.lazy first to False then to True?

Answer 1

By default, T() is lazy — when you call it, it doesn’t actually do the translation but instead returns a lazyT object, which isn’t translated until serialized in a view. If you set T.lazy=False, that will force immediate translation, so calling T('some string') will return the actual translated string instead of a lazyT object.

Note, starting with the upcoming release, instead of having to toggle T.lazy to False and True, you will be able to do T('some string', lazy=False) to force an immediate translation for a single call. Other ways to force immediate translation are str(T('some string')) or T('some string').xml() — str() serializes the lazyT object (and .xml() simply calls str()).