Scope and classes
bruno.42.desthuilliers at websiteburo.invalid
Wed Aug 19 11:31:55 CEST 2009
David a écrit :
> Out of 'Abc.message' and 'self.message', which is the favoured
> convention? It would be very easy to accidentally override
> 'self.messages' with an instance attribute!
Only use 'Abc.message' if you want to make sure you get the Abc class
'message' attribute - that is, if you want to skip possible overrides in
subclasses. As far as I'm concerned, I'd tend to consider this bad style
unless it's a very very specific implementation point of an abstract
class (in which case it would probably be named '__message' to prevent
accidental override) - but YMMV of course.
Use 'self.__class__.message' (or 'type(self).message') if you want to
make sure you get the class 'message' attribute - that is, if you want
to honor possible overrides in subclasses, but not per-instance
override. But then - at least in your example code - I'd use a classmethod:
message = 'Hello World'
Now the most common idiom - that is, outside classmethods - is to just
use 'self.message'. Someone (even you) might have a very valid reason to
override the 'message' attribute on a per-instance basis. FWIW, if you
start to worry about possible accidental overrides here, then Python
might not be the right language for you - nothing prevents "accidental"
overrides of method and even the class (the '__class__' attribute)
itself - yes, they are all attributes, and you can dynamically override
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