import traceback
from Delegator import Delegator

class Callable(object):
    def __call__(self, *args, **kw):
        return args, kw

    def method(self, *args, **kw):
        return args, kw

##if __name__ == '__main__':
##    delegator = Delegator(Callable())
##
##    print 'Normal method call:',
##    print delegator.method('one', two='two')
##
##    print '"Direct" call (the underlying object is callable):',
##    try:
##        print delegator('one', two='two')
##    except:
##        print
##        traceback.print_exc()


## Note that I am avoiding the use of the words 'delegate' and 'delegator' !!!
if __name__ == '__main__':
    instance_of_callable = Callable()
    filter = Delegator(instance_of_callable)
    ## filter is a pure DelegatorNode. It has no methods of its own.

    print 'Normal method call:',
    print filter.method('one', two='two')
    ## since filter has no 'method' method, it calls
    ## through to instance_of_callable.  That's fine, but filter isn't useful.

    print '"Direct" call (the underlying object is callable):',
    try:
        print filter('one', two='two')
        ## As a callable, filter does nothing on its own.  When it's called, it
        ## passes the call through to instance_of_callable (assuming that
        ## the the Delegator class has a __call__() method).

        ## What are you trying to accomplish by the call to filter()?
        ## Why not just call instance_of_callable()?

        ## This is not how filters are implemented.  The chain of authority
        ## machinery is a mixin.  ColorDelegator should be renamed Colorizer.
        ## Its main job is to colorize a Text instance.  Relaying the calls
        ## insert() and delete() down the chain is necessary, but not central.

        ## For filter to be useful, it has to be a class with a DelegatorNode
        ## mixin.  And when you want it to be callable, you need to define a
        ## __call__() method in the Filter class.  That method will do something
        ## in filter, and then possibly pass some action down the chain.
        ## See example2.py.

        
    except:
        print
        traceback.print_exc()