How to get self into a Python method without explicitly accepting it

Question

I\'m developing a documentation testing framework -- basically unit tests for PDFs. Tests are (decorated) methods of instances of classes defined by the framework, and these

Answer 1

The trick is to add 'self' to f.func_globals. This works in python2.6. I really should get around to installing other versions to test stuff like this on. Sorry for the wall of code but I cover two cases: doing it with a metaclass and doing it with a decorator. For your usecase, I think the metaclass is better since the whole point of this exercise is to shield users from syntax.

import new, functools

class TestMeta(type):
    def __new__(meta, classname, bases, classdict):
        for item in classdict:
            if hasattr(classdict[item], '__call__'):
                classdict[item] = wrap(classdict[item])
        return type.__new__(meta, classname, bases, classdict)

def wrap(f):
    @functools.wraps(f)
    def wrapper(self):
        f.func_globals['self'] = self        
        return f()
    return wrapper

def testdec(f):
    @functools.wraps(f)
    def wrapper():
        return f()
    return wrapper

class Test(object):
    __metaclass__ = TestMeta
    message = 'You can do anything in python'
    def test():
        print self.message

    @testdec
    def test2():
        print self.message + ' but the wrapper funcion can\'t take a self argument either or you get a TypeError'

class Test2(object):
    message = 'It also works as a decorator but (to me at least) feels better as a metaclass'
    @wrap
    def test():
        print self.message


t = Test()
t2 = Test2()
t.test()
t.test2()
t2.test()