[Python-3000] two things

[Antoine Pitrou]

Le samedi 25 novembre 2006 à 21:32 +0200, tomer filiba a écrit :
> "contract" is a better term, IMO, since it's already used in CS (as in Eiffel),
> and describes the situation more correctly: *behavior* rather than *signature*.
> "ability" just doesn't seem right to me: my class is not *able* to be a set,
> it *behaves* like a set.

You can simply call it a behaviour rather than a contract.

Contract-based programming is usually defined as involving pre- and
post-conditions on method calls, to check that the method behaves as
expected. The underlying idea is that the terms of the contract are
programmatically enforced rather than simply declared.

Wikipedia mentions those attempts at contract-based programming with
Python:
http://www.nongnu.org/pydbc/
http://www.wayforward.net/pycontract/
http://www.targeted.org/python/recipes/ipdbc.py

> instead of the suggested /defop/ keyword, which seems very awkward to me,
> i'd prefer an extension to the current function syntax:
> 
> def __contains__(self) of MinimalSet:
>     pass

Other suggestion:

from MinimalSet def __contains__(self):
    pass

The "origin" of the method is then clearly visible instead of being
relegated at the end of the declaration (it works better with multi-line
declarations too). Also the class declaration look nicer when you have
several of these methods:

class BazContainer:
    # Implement methods from MinimalSet

    from MinimalSet def __contains__(self):
        pass

    from MinimalSet def add(self):
        pass

    from MinimalSet def remove(self):
        pass

    # Other methods

    def to_bicycle(self):
        """ Turn this container into a bicycle """

    (etc.)