Very, Very Green Python User

[Bruno Desthuilliers]

hanumizzle at gmail.com a écrit :
> bruno at modulix wrote:
> 
(snip)
>>You don't even need this to use callbacks. Remember, functions and
>>methods are objects, and other objects can be callable too...
>  
> Eh?? I need an example.

Of callables ?

class FuncInDisguise(object):
   def __init__(self, name):
     self.name = name

   def __call__(self, who):
     return "Hello, %s, my name is %s" % (who, self.name)

hello_from_bruno = FuncInDisguise("bruno")
print hello_from_bruno("hanumizzle")

It's somewhat equivalent to a more functional :

def curry(fun, *args):
   def _curried(*moreargs):
     return fun(*(args + moreargs))
   _curried.func_name = "curried(%s) of %r" % (", ".join(args), fun)
   return _curried

def greeting(name, who):
   return "Hello, %s, my name is %s" % (who, name)

hello_from_bruno2 = curry(greeting, "bruno")
print hello_from_bruno2("hanumizzle")


Now when it comes to callbacks, just pass around any callable with a 
compatible signature, and this should Just Work(tm):

def test(callback):
   result = callback('baaz')
   print "in test, got: '%s'" % result
   return result

class Foo(object):
   def __init__(self, name):
     self.name = name

  def doit(self, arg):
    return "%s %s" % (self.name, arg)

f = Foo('bar')

print test(f.doit)
print test(hello_from_bruno)
print test(hello_from_bruno2)
print test(FuncInDisguise)
print test(lambda n: "what should I do with %s ?" % n)
print test(lambda n: ("what should I do with %s ?" % n).split)

And why we're at it, why not have some fun calling the result of a 
callback ?-)

print test(FuncInDisguise)('madman')
print test(lambda n: ("what should I do with %s ?" % n).split)()

HTH