Is it possible (and wise) to extend the None-type ?

[John Machin]

On Nov 27, 4:55 am, Stef Mientki <stef.mien... at gmail.com> wrote:
> hello,
>
> I've the idea that I always have a lot of useless code in my programs,
> like the next example.
>
>   def _On_Menu_File_Open ( self, event = None ):
>     if event :
>      event.Skip ()
>
> instead of
>
>   def _On_Menu_File_Open ( self, event = None ):
>    event.Skip ()
>
> So I would like to extend the None-type (if that's possible),
> with a dummy Skip() method.
>
> Is it wise to do ?

No.

> If not what are the disadvantages ?

Assume that as well as your Event class, you also have a Foo class
with a dothis method and a Bar class with a dothat1 and a dothat2
method: you would need to extend the None-type (if that's possible) to
have dummy skip, dothis, dothat1 and dothat2 methods. Each time you
invent a new class, you need to consider adding one or more new dummy
methods to your extended None-type.

Alternative (if you *really* want to save the explicit test) is to
attach the behaviour modification to the *relevant* class:

class NonEvent(Event):
   def do_nothing(self):
      pass
   skip = jump = hop = waltz = saunter = do_nothing
   def __len__(self):
      return 0
NON_EVENT = NonEvent()
del NonEvent

# later:

def amethod(self, event=NON_EVENT):
   if event: # still works thanks to __len__ above
      event.skip()
   # now can avoid test, if desired
   event.skip()

HTH ... BTW, ever heard of PEP 8?

Cheers,
John