z3c.discriminator 0.2

Provides a formalism for marking adapter specifications as discriminators.

Overview

z3c.discriminator provides a formalism for marking adapter specifications as discriminators in the sense that they will be used only for adapter lookup, not instantiation.

Using z3c.discriminator

To mark one or more interfaces as discriminators in a provideAdapter call, simply wrap your interface with the discriminator method:

>>> from z3c.discriminator import discriminator
>>> provideAdapter(MyAdapter, (IFoo, discriminator(IBar)))

To do the same in a Zope configuration file, prefix your dotted path with a dash like so:

<adapter for="IFoo -IBar" factory="some.package.YourFactory" />

Note that any interface in the declaration can be made a discriminator; they need not come in any particular order.

In your factory definition, simply require only the arguments that correspond to non-discriminator specifications, e.g.

class GetsOnlyFoo(object): def __init__(self, foo): ...

-or-

def gets_only_bar(bar): ...

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