Magical self update

def selfupdate(onlyargs=False, exclude=[]):
    """Call in any method to set instance attributes from local variables.
 
    @param onlyargs: If True, use only named arguments and not locals
 
    @param exclude: Names of other variables to exclude.
 
    @note: First argument to the caller is taken to be the "self" to update
 
    @note: Equivalent to 'vars(self).update(vars()); del self.self'
    """
    import inspect
    # Get caller frame (must be disposed of!)
    cf = inspect.currentframe().f_back 
    try:
        # Instance is first argument to the caller
        instance = cf.f_locals[cf.f_code.co_varnames[0]]
        # Get names of variables to use
        if onlyargs:
            varnames = cf.f_code.co_varnames[1:cf.f_code.co_argcount]
        else:
            varnames = cf.f_code.co_varnames[1:]
        # Update instance with those names
        for var in varnames:
            if var not in exclude:
                setattr(instance, var, cf.f_locals[var])
    finally:
        del cf
 
 
def testSelfUpdate(self):
    """For utils.selfupdate()"""
    class X:
        a = 1
        def __init__(s, a, b):
            c = 3
            selfupdate()
    x = X(2,4)
    self.assertEqual(x.a,2)
    self.assertEqual(x.b,4)
    self.assertEqual(x.c,3)
 
 
def update(instance, variables, exclude=['self']):
    """Update instance attributes
 
    For example, C{update(self, locals())},
which is less magical than L{selfupdate}.
 
    @param instance: Instance to update via setattr()
    @param variables: Dictionary of variables
    @param exclude: Variables to exclude, defaults to ['self']
    """
    for k, v in variables.iteritems():
        if k not in exclude:
            setattr(instance, k, v)