I want to have a wrapper class that behaves exactly like the object it wraps except that it adds or overwrites a few select methods.
My code currently looks like this:
# Create a wrapper class that equips instances with specified functions
def equipWith(**methods):
class Wrapper(object):
def __init__(self, instance):
object.__setattr__(self, 'instance',instance)
def __setattr__(self, name, value):
object.__setattr__(object.__getattribute__(self,'instance'), name, value)
def __getattribute__(self, name):
instance = object.__getattribute__(self, 'instance')
# If this is a wrapped method, return a bound method
if name in methods: return (lambda *args, **kargs: methods[name](self,*args,**kargs))
# Otherwise, just return attribute of instance
return instance.__getattribute__(name)
return Wrapper
In order to test this out I wrote:
class A(object):
def __init__(self,a):
self.a = a
a = A(10)
W = equipWith(__add__ = (lambda self, other: self.a + other.a))
b = W(a)
b.a = 12
print(a.a)
print(b.__add__(b))
print(b + b)
When on the last line, my interpreter complains:
Traceback (most recent call last):
File "metax.py", line 39, in <module>
print(b + b)
TypeError: unsupported operand type(s) for +: 'Wrapper' and 'Wrapper'
Why is this? How can I get my wrapper class to behave the way I want it to?