MoinMoin: attachment:objproxy.py of ThomasWaldmann

   1 """ Object proxy
   2 
   3     Getting into the middle between some application code and e.g.
   4     some library module by intercepting all calls and logging all results.
   5 """
   6 from types import *
   7 
   8 class Proxy(object):
   9     def __init__(self, wrapped):
  10         # remember the object we wrap:
  11         self.wrapped = wrapped
  12         # for prettier logging - find out name of object:
  13         if hasattr(wrapped, '__name__'):
  14             self.name = wrapped.__name__
  15         elif hasattr(wrapped, '__class__'):
  16             self.name = wrapped.__class__
  17         else:
  18             self.name = 'Unknown'
  19 
  20     def log(self, format, *args):
  21         print "Proxy: %s." % self.name + format % args
  22 
  23     def need_proxy(self, obj):
  24         """ checks if we need a proxy object """
  25         # XXX is there a better way to check if we want to proxy?
  26         if isinstance(obj, (
  27             NoneType,
  28             TypeType,
  29             IntType,
  30             LongType,
  31             FloatType,
  32             BooleanType,
  33             ComplexType,
  34             StringTypes,
  35             BufferType,
  36             TupleType,
  37             ListType,
  38             DictType,
  39             DictProxyType,
  40             GeneratorType,
  41             BuiltinFunctionType,
  42             BuiltinMethodType,
  43             ClassType,
  44             UnboundMethodType,
  45             FileType,
  46             XRangeType,
  47             SliceType,
  48             EllipsisType,
  49             NotImplementedType,
  50             )):
  51             # it is something simple, we don't need a proxy
  52             return False
  53 
  54         if isinstance(obj, (
  55             FunctionType,
  56             InstanceType,
  57             MethodType,
  58             ModuleType,
  59             )):
  60             # something complex, like functions, class instances, modules, ...
  61             return True
  62 
  63         # something not listed above
  64         return False
  65 
  66     def __getattr__(self, name):
  67         wrapped = getattr(self.wrapped, name)
  68         if self.need_proxy(wrapped):
  69             return Proxy(wrapped)
  70         else:
  71             self.log("%s -> %r", name, wrapped)
  72             return wrapped
  73 
  74     def __call__(self, *args, **kw):
  75         result = self.wrapped(*args, **kw)
  76         self.log("call(%r %r) --> %r", args, kw, result)
  77         if self.need_proxy(result):
  78             return Proxy(result)
  79         else:
  80             return result
  81 
  82 # testing (all output generated comes from the proxy):
  83 if __name__ == '__main__':
  84     import sys
  85     import ldap
  86     ldap = sys.modules['ldap'] = Proxy(sys.modules['ldap'])
  87 
  88     ldap.PORT
  89     lo = ldap.initialize("ldap://localhost")
  90     lo.timelimit