Stack Attribute Trick

getattr.py

def __getattr__(self,name):
        """Provides a passthrough for functions that we haven't named yet.
        
        This allows *stacks* to call methods defined within *frames*. Most frames define a :meth:`~BaseFrame.__show__`. This method can be called using :meth:`show` with the following syntax::
            
            >>> Stack.show("SomeFrameName")
            
        The special syntax can take as many framenames as desired as arguments, and will call the named method on each one. So::
            
            >>> Stack.show("FrameA","FrameB","FrameC")
            
        will call the :meth:`~BaseFrame.__show__` method on each frame.
        
        """
        def __attr_method(*framenames):
            # Set up frame method name (as string)
            method = '__' + name + '__'
            # Initialize return values
            rvals = []
            
            framenames = list(*framenames)
            if len(framenames) < 1:
                framenames = [self._default_frame()]
                
            # Execute the desired method everywhere
            for framename in framenames:
                if framename != None and framename in self:
                    rvals += [ getattr(self[framename],method)() ]
                else:
                    self._key_error(framename)
            
            # Return the appropriate value
            if len(rvals) == 1:
                return rvals[0]
            elif len(rvals) == 0:
                return None
            else:
                return tuple(rvals)
                
        return __attr_method