def set_jinja2(jinja2, key=_registry_key, app=None):
"""Sets an instance of :class:`Jinja2` in the app registry.
:param store:
An instance of :class:`Jinja2`.
:param key:
The key used to retrieve the instance from the registry. A default
is used if it is not set.
:param request:
A :class:`webapp2.WSGIApplication` instance used to retrieve the
instance. The active app is used if it is not set.
"""
app = app or webapp2.get_app()
app.registry[key] = jinja2
def get_jinja2(factory=Jinja2, key=_registry_key, app=None):
"""Returns an instance of :class:`Jinja2` from the app registry.
It'll try to get it from the current app registry, and if it is not
registered it'll be instantiated and registered. A second call to this
function will return the same instance.
:param factory:
The callable used to build and register the instance if it is not yet
registered. The default is the class :class:`Jinja2` itself.
:param key:
The key used to store the instance in the registry. A default is used
if it is not set.
:param app:
A :class:`webapp2.WSGIApplication` instance used to store the instance.
The active app is used if it is not set.
"""
app = app or webapp2.get_app()
jinja2 = app.registry.get(key)
if not jinja2:
jinja2 = app.registry[key] = factory(app)
return jinja2
