#!/usr/bin/env python

# Written by: DGC

# http://sourcemaking.com/design_patterns/proxy

# give 4 good reasons for a proxy to be made.

# A virtual proxy is a placeholder for "expensive to create" objects. The real

# object is only created when a client first requests/accesses the object.

#

# A remote proxy provides a local representative for an object that resides in

# a different address space. This is what the "stub" code in RPC and CORBA

# provides.

# A protective proxy controls access to a sensitive master object. The

# "surrogate" object checks that the caller has the access permissions required

# prior to forwarding the request.

# A smart proxy interposes additional actions when an object is accessed.

# Typical uses include:

# o Counting the number of references to the real object so that it can be

# freed automatically when there are no more references (aka smart pointer)

# o Loading a persistent object into memory when it's first referenced,

# o Checking that the real object is locked before it is accessed to ensure

# that no other object can change it.

#==============================================================================

class SharedData(object):

def __init__(self):

self.resource = "A resource"

#==============================================================================

class AsyncProxy(object):

def __init__(self, data):

"""

Takes some data which should now only be accessed through this class,

otherwise you could get

"""

self.data = data