J. Clifford Dyer a écrit : > On Mon, Nov 19, 2007 at 01:41:46PM +0100, Bruno Desthuilliers wrote regarding > Re: overriding methods - two questions: >> Steven D'Aprano a ?crit : >>> On Fri, 16 Nov 2007 18:28:59 +0100, Bruno Desthuilliers wrote: >>> >>>>> Question 1: >>>>> >>>>> Given that the user of the API can choose to override foo() or not, how >>>>> can I control the signature that they use? >>>> While technically possible (using inspect.getargspec), trying to make >>>> your code idiot-proof is a lost fight and a pure waste of time. >>> >>> Worse: it's actually counter-productive! >>> >>> The whole idea of being able to subclass a class means that the user >>> should be able to override foo() *including* the signature. >> If you see subclassing as subtyping, the signatures should always stay >> fully compatibles. >> > > Isn't that more what Zope-type interfaces are for than inheritance?
With dynamically typed languages like Python, you don't need any formal mechanism (zope-like interface or whatever) for subtyping to work - just make sure your two classes have the same public interface and it's ok. So indeed inheritance is first a code-reuse feature. > I'm uncertain here, but I'm not persuaded that changing signature is > bad. Depends if the subclass is supposed to be a proper subtype (according to LSP) too. -- http://mail.python.org/mailman/listinfo/python-list
