wrapping_methods_example.py

#!/usr/bin/env python3
from types import FunctionType
from functools import wraps

def wrapper(method):
    @wraps(method)
    def wrapped(*args, **kwrds):
        """ Adds 1 to the value returned by wrapped method function. """
        # first arg of class methods is class instance -- aka "self"
        class_name = args[0].__class__.__name__
        func_name = method.__name__
        print('calling {}.{}()... '.format(class_name, func_name))
        return method(*args, **kwrds) + 1
    return wrapped

class MetaClass(type):
    def __new__(meta, class_name, bases, classDict):
        newClassDict = {}
        for attributeName, attribute in classDict.items():
            if isinstance(attribute, FunctionType):
                # replace it with a wrapped version
                attribute = wrapper(attribute)
            newClassDict[attributeName] = attribute
        return type.__new__(meta, class_name, bases, newClassDict)

class MyClass(MetaClass('NewBaseClass', (object,), {})):  # creates base class
    def method1(self, arg):
        """ Adds 1 to the value of its argument and returns it. """
        print('MyClass.method1({}) called'.format(arg))
        return arg + 1

print('MyClass().method1(40) -> {}'.format(MyClass().method1(40)))

# Output:
#
#     calling MyClass.method1()...
#     MyClass.method1(40) called
#     MyClass().method1(40) -> 42