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django/django/utils/decorators.py
2009-10-15 20:25:20 +00:00

101 lines
4.0 KiB
Python

"Functions that help with dynamically creating decorators for views."
import types
try:
from functools import wraps, update_wrapper
except ImportError:
from django.utils.functional import wraps, update_wrapper # Python 2.3, 2.4 fallback.
# Licence for MethodDecoratorAdaptor and auto_adapt_to_methods
#
# This code is taken from stackoverflow.com [1], the code being supplied by
# users 'Ants Aasma' [2] and 'Silent Ghost' [3] with modifications. It is
# legally included here under the terms of the Creative Commons
# Attribution-Share Alike 2.5 Generic Licence [4]
#
# [1] http://stackoverflow.com/questions/1288498/using-the-same-decorator-with-arguments-with-functions-and-methods
# [2] http://stackoverflow.com/users/107366/ants-aasma
# [3] http://stackoverflow.com/users/12855/silentghost
# [4] http://creativecommons.org/licenses/by-sa/2.5/
class MethodDecoratorAdaptor(object):
"""
Generic way of creating decorators that adapt to being
used on methods
"""
def __init__(self, decorator, func):
update_wrapper(self, func)
# NB: update the __dict__ first, *then* set
# our own .func and .decorator, in case 'func' is actually
# another MethodDecoratorAdaptor object, which has its
# 'func' and 'decorator' attributes in its own __dict__
self.decorator = decorator
self.func = func
def __call__(self, *args, **kwargs):
return self.decorator(self.func)(*args, **kwargs)
def __get__(self, instance, owner):
return self.decorator(self.func.__get__(instance, owner))
def auto_adapt_to_methods(decorator):
"""
Takes a decorator function, and returns a decorator-like callable that can
be used on methods as well as functions.
"""
def adapt(func):
return MethodDecoratorAdaptor(decorator, func)
return wraps(decorator)(adapt)
def decorator_from_middleware_with_args(middleware_class):
"""
Like decorator_from_middleware, but returns a function
that accepts the arguments to be passed to the middleware_class.
Use like::
cache_page = decorator_from_middleware_with_args(CacheMiddleware)
# ...
@cache_page(3600)
def my_view(request):
# ...
"""
return make_middleware_decorator(middleware_class)
def decorator_from_middleware(middleware_class):
"""
Given a middleware class (not an instance), returns a view decorator. This
lets you use middleware functionality on a per-view basis. The middleware
is created with no params passed.
"""
return make_middleware_decorator(middleware_class)()
def make_middleware_decorator(middleware_class):
def _make_decorator(*m_args, **m_kwargs):
middleware = middleware_class(*m_args, **m_kwargs)
def _decorator(view_func):
def _wrapped_view(request, *args, **kwargs):
if hasattr(middleware, 'process_request'):
result = middleware.process_request(request)
if result is not None:
return result
if hasattr(middleware, 'process_view'):
result = middleware.process_view(request, view_func, args, kwargs)
if result is not None:
return result
try:
response = view_func(request, *args, **kwargs)
except Exception, e:
if hasattr(middleware, 'process_exception'):
result = middleware.process_exception(request, e)
if result is not None:
return result
raise
if hasattr(middleware, 'process_response'):
result = middleware.process_response(request, response)
if result is not None:
return result
return response
return wraps(view_func)(_wrapped_view)
return auto_adapt_to_methods(_decorator)
return _make_decorator