repoze.bfg.traversaladapter 0.1

An alternate implementation of the repoze.bfg.interfaces.ITraverserFactory (a “traverser”) which allows you to register an adapter factory for the type or interface(s) of objects encountered during traversal. This is a generalization of the repoze.bfg.traversalwrapper package which automatically wraps each traversed object into a location-aware proxy.

To enable this custom traverser factory, you need to add a dependency on repoze.bfg.traversaladapter to your application and replace the default traverser factory in the configure.zcml configuration file like this:

<adapter
    factory="repoze.bfg.traversaladapter.ModelGraphTraverser"
    provides="repoze.bfg.interfaces.ITraverserFactory"
    for="*"
    />

Given a simple factory for adapters for a model class mymodule.Foo defined in the module mymodule like this

def foo_factory(foo, parent, name):
    return FooAdapter(foo, parent, name)

you could then register foo_factory as a traversal adapter factory as follows:

<adapter
    factory="mymodule.foo_factory"
    provides="repoze.bfg.traversaladapter.ITraversalAdapterFactory"
    for="mymodule.Foo"
    />

If Foo was implementing the interface mymodule.IFoo, the following registration would also work:

<adapter
    factory="mymodule.foo_factory"
    provides="repoze.bfg.traversaladapter.ITraversalAdapterFactory"
    for="mymodule.IFoo"
    />

During traversal of your repoze.bfg application, each object of type Foo will then automatically be wrapped in a FooAdapter instance.

Note that the registered factory always gets the current model object, its parent and its name passed as arguments. If your FooAdapter class was set up to receive a Foo instance, a parent object, and a name string in its constructor like so

class FooAdapter(object):
    def __init__(self, foo, parent, name):
        self.foo = foo
        self.parent = parent
        self.name = name

you could register the adapter class itself as the adapter factory.

See the repoze.bfg.traversaladapter.tests.TraversalAdapterTests module for further examples.