gistfile1.py

import time
from traceback import extract_stack, format_list

def wrap_func(base_class):
    def check_func(f):
        old_func_name = 'old%s' % (f.__name__,)
        if hasattr(base_class, f.__name__):
            setattr(base_class, old_func_name,
                    getattr(base_class, f.__name__))
        def new_func(*args, **kwargs):
            f(*args, **kwargs)
            if hasattr(base_class, old_func_name):
                return getattr(base_class, old_func_name)(*args, **kwargs)
        setattr(base_class, f.__name__, new_func)
        return new_func
    return check_func

def record(base_class):
    """Record the interactions on a specific class.

    This method will take a class and wrap __setattr__ and record any time a
    __setattr__ occurs with the name, value, time and *where* it was set from
    via. the stack. Any potential name clashes after being wrapped first call
    the wrapper's functions and then the base class'. The eventual, return
    value will be from your function and not this class. To get any object's
    history after being wrapped by this class, just call dump_history().

    Usage:
        @record
        class A:
            foo = 1

        bar = A()
        bar.foo = 2
        bar.dump_history()

    At runtime (or in the interpreter), instead of using the class decorator,
    you can use:
        A = record(A)
    """
    @wrap_func(base_class)
    def __init__(self, *args, **kwargs):
        self._history = []

    @wrap_func(base_class)
    def __setattr__(self, key, value):
        if key != "_history":
            self._history.append((key, value, time.time(),
                                  extract_stack()[:-1]))
        if not hasattr(self, 'old__setattr__'):
            self.__dict__[key] = value

    @wrap_func(base_class)
    def dump_history(self):
        for key, value, t, stack in self._history:
            print '%s = %s' % (key, value)
            print '@= %s' % (t,)
            print ''.join(format_list(stack))
            print '--------------------'

    return base_class