How to intercept instance method calls?

Question

I am looking for a way to intercept instance method calls in class MyWrapper below:

class SomeClass1:
    def a1(self):
        self.internal_z         


        

Answer 1

What you want to do is quite similar to this question. You should take your example code in the reverse order, i mean creating a class to record return values of method calls, and make the classes you want to watch inherit from it. Which would give something like this

class RetValWatcher(object):
    def __init__(self):
        self.retvals = []

    def __getattribute__(self, name):
        attr = super(RetValWatcher, self).__getattribute__(name)
        if callable(attr):
            def wrapped(*args, **kwargs):
                retval = attr(*args, **kwargs)
                self.retvals.append(retval)
                return retval
            return wrapped
        else:
            return attr

    def getFinalRestult(self):
        return ''.join(self.retvals)

class MyClass(RetValWatcher):
    def a(self):
        self.internal_z()
        return 'a1'

    def b(self):
        return 'b1'

    def internal_z(self):
        return 'z'

x = MyClass()
x.a()
x.b()
print x.getFinalResult()
#'za1b1'

With some minor changes, this method would also allow you to record return values across all RetValWatcher instances.

Edit: added changes suggested by singularity's comment

Edit2: forgot to handle the case where attr is not a method (thx singularity again)