status of Programming by Contract (PEP 316)?

Chris Mellon arkanes at gmail.com
Fri Aug 31 01:50:59 CEST 2007


On 8/30/07, Russ <uymqlp502 at sneakemail.com> wrote:
>
> Bruno Desthuilliers wrote:
> > Russ a écrit :
> > (snip)
> >
> > > I don't see how you can avoid adding some new syntax, given that
> > > Python does not
> > > currently have syntax for specifying invariants and pre- and post-
> > > conditions.
> >
> > class Parrot(object):
> >    @pre(lambda x : x != 42)
> >    @post(lambda result: result != 42)
> >    @invariant(lambda self: self.x == 42)
> >    def reliable_method(self, x):
> >      # your code here
> >      return something
>
> That looks like new syntax to me. Did I miss your point?
>
> I have no strong leaning about what the exact syntax should be for
> programming by contract.
> The syntax you show above seems reasonable, except that I am not sure
> about requiring
> that everything be put inside parentheses. That seems a bit confining
> for more complex
> conditions.
>

This is existing, working python syntax (although the decorators would
need to be defined).

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