Ratko a écrit :
> bruno a écrit
>>Another solution is to compare the functions wrapped by the methods:
>>
>>class EvtHandler:
>> def __init__(self):
>> onKey = getattr(self, 'onKey')
>> if onKey.im_func is EvtHandler.onKey.im_func:
s/is/is not/, of course
>> register_for_key_events()
>>
>> def onKey(self):
>> pass
>>
>>class MyHandler(EvtHandler):
>> def onKey(self):
>> # do something here....
>>
>>HTH
>
>
> The second solution works beautifully!
Hem... Almost !-)
> Thank you very much.
> I was aware that not implementing the onKey method in the first place
> is the simplest solution but it's much cleaner to offer the methods in
> advance so that the user can see what is possible.
Yeps - a placeholder 'abstract' method with only a docstring. It's a
common pattern in frameworks, but usually it's just an ordinary template
method pattern defaulting to a no-op.
FWIW, if you have several such methods to handle, you can use a more
generic approach:
_handlers = {
'onKey':registerForKeyEvents,
'onClick':registerForMouseEvents,
} # etc
class EventHandler(object):
for _name in _handlers:
exec "%s=lambda self, *args, **kw: pass" % _name
def __new__(cls, *args, **kw):
obj = object.__new__(cls, *args, **kw)
for name, register_func in _handlers.items():
meth = getattr(obj, name)
dummy = getattr(EventHandler, name)
if meth.im_func is not dummy.im_func:
register_func(meth)
return obj
HTH
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