> The difference between objects is measeured by their interfaces not their
> data
> so provided the supplier objects all use the same operations of a Flavor then
> its not too bad. You can either create subclasses of Flavor for each
> manufacturer that retuirns the requisite list of attributes (but requires
> ongoing changes for every new manufacturer - eek!) or you can write a method
> of
> Flavor that takes a list (or dictionary?) of required attributes and returns
> the
> values. It can also raise exceptions if asked for unsupported attributes, or
> return None, in which case the Supplier object provides a suitable default.
>
Hmm. I'll have to read that a couple of times.
> This way you can limit the changes for a new supplier. You might also be able
> to
> data drive the Supplier object to make the required list of attributes
> configurable(via a database or file?). Then you only need subclasses of
> Supplier
> for the actual interface types (EDI, v FTP, v http v email etc).
>
> > How should the mapping between the CanonicalFlavor('Vanilla') object and
> ManufAFlavor('Vanilla') / ManufBFlavor('Vanilla') objects be handled.
>
> If the mapping is one to many I don;t think you need to maintain it - at
> least
> not in the objects. Just pass the Flavor object to the supplier object. Let
> the
> supplier query the Flavor for the data it needs.
>
> If the choice of supplier was driven by Flavor characteristics then the
> selection method would be in the Flavour and then you'd need to keep a list
> of
> suppliers in the Flavor. But since
> the supplier is chosen from external factors the Flavor doesn't need to know
> about its supplier. And the supplier only needs to know about how to query a
> flavour.
>
What about just Flavor() objects and a customised "per-manufacture" SupplierA()
/ SupplierB() objects that internally knows how to generate an order from a
passed in Flavor() object? (Which would also raise a CantMakeFlavor error if
this manufature can't supply the required flavor.)
_______________________________________________
Tutor maillist - Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor
