metaprogramming (inspired by dave beazley)

mp.py

def dec(*a, **k):
    print(a,k)
    return a[0] if a else lambda self: self


def debug(f, pre='[debug]', indent='.', inc=1):
    depth = 0
    def _(*a,**k):
        nonlocal indent
        nonlocal depth
        ind = indent*depth
        print(pre, ind, f, a, k)
        depth += inc
        r = f(*a, **k)
        print(pre, ind, r)
        depth -= inc
        return r
    return _

class Meta(type):
    def __new__(mcs, name, bases, dct):
        print(type(dct), dct)
        new = {}
        for k in dct:
            if callable(dct[k]):
                print('tracable',k)
                dct[k] = debug(dct[k])
            else:
                print('else',k)
                if not k.startswith('__'):
                    new['get_'+k] = lambda self: (self, getattr(self,k))
        print(new)
        return type.__new__(mcs, name, bases, {**dct,**new})


class M(metaclass=Meta):
    x = 1

    def fact(self,n):
        if n < 2:
            return 1
        else:
            return n*self.fact(n-1)

    @dec
    def f(self):
        return self