有没有办法将变量传递给装饰器？

Question

I have log in system, based on OpenID provider, and I want to create decorator like @login_required. But I have a problem - I need to check permission per object. I pass id to my views, so I want to know is there any way to pass it to decorator or it's impossible and I need to check users permission in my view.

Answer 1

def outer(var1, var2):
    def inner(func)
        func.foo = var1
        func.bar = var2
        return func
    return inner

@outer(myvar1, myvar2)
def myfunc():
    # whatever
    pass

While you can't pass variables directly to the function which decorates your function, you can create another function ( outer ) that, when called, returns the decorating function ( inner ). You pass the outer function variables, and they are available to the inner function. This is called a closure.

Answer 2

Depending on when you need to do the stuff with the id you may need two levels of wrapping where you replace print(permission_id) with whatever it is you need to do before the method is called:

def login_required(permission_id):
    def decorator(func):
        def method(self, *args, **kw):
            print(permission_id)
            return func(self, *args, **kw)
        return method
    return decorator

class foo(object):

    @login_required('foo')
    def bar(self):
        print('bar')

foo = foo()
print('instantiated')
foo.bar()

Outputs:

instantiated
foo
bar