flask/flask/ext/__init__.py

62 lines
2 KiB
Python

# -*- coding: utf-8 -*-
"""
flask.ext
~~~~~~~~~
Redirect imports for extensions. This module basically makes it possible
for us to transition from flaskext.foo to flask_foo without having to
force all extensions to upgrade at the same time.
When a user does ``from flask.ext.foo import bar`` it will attempt to
import ``from flask_foo import bar`` first and when that fails it will
try to import ``from flaskext.foo import bar``.
We're switching from namespace packages because it was just too painful for
everybody involved.
:copyright: (c) 2011 by Armin Ronacher.
:license: BSD, see LICENSE for more details.
"""
class _ExtensionImporter(object):
"""This importer redirects imports from this submodule to other locations.
This makes it possible to transition from the old flaskext.name to the
newer flask_name without people having a hard time.
"""
_module_choices = ['flask_%s', 'flaskext.%s']
def __init__(self):
from sys import meta_path
self.prefix = __name__ + '.'
self.prefix_cutoff = __name__.count('.') + 1
def _name(x):
cls = type(x)
return cls.__module__ + '.' + cls.__name__
this = _name(self)
meta_path[:] = [x for x in meta_path if _name(x) != this] + [self]
def find_module(self, fullname, path=None):
if fullname.startswith(self.prefix):
return self
def load_module(self, fullname):
from sys import modules
if fullname in modules:
return modules[fullname]
modname = fullname.split('.', self.prefix_cutoff)[self.prefix_cutoff]
for path in self._module_choices:
realname = path % modname
try:
__import__(realname)
except ImportError:
continue
module = modules[fullname] = modules[realname]
setattr(modules[__name__], modname, module)
return module
raise ImportError(fullname)
_ExtensionImporter()
del _ExtensionImporter