Intercept methods/raise exception

[Gordon McMillan]

Thomas Weholt wrote:

>Is there a way to define a method in a class that is called each time
>every other method is called in that class, and based on a attribute,
>raise an exception or let the method-class go thru?

Not with a method. Use a proxy:

class Proxy:
  def __init__(self, obj):
    self.__dict__['_obj'] = obj # avoid the __setattr__ hook
  def __getattr__(self, nm):
    attr = getattr(self._obj, nm, None)
    if attr:
      # do what you like
      return attr
    raise AttributeError, "%s not found" % nm  	# vital 
  def __setattr__(self, nm, val):
    # do what you like and maybe
    setattr(self._obj, nm, val)

Now just wrap your object in the proxy.

-Gordon