grokcore.component 1.0

Base classes

Adapter

Base class for an adapter that adapts a single object (commonly referred to as the context). Use the context directive to specify which object to adapt and the implements directive to specify which interface the adapter will provide. If it’s a named adapter, you may use the name directive to specify the name.

MultiAdapter

Base class for an adapter that adapts n objects (where n>=1). Use the adapts directive to specify which kinds of objects are adapted and the implements directive to specify which interface the adapter will provide. If it’s a named multi-adapter, you may use the name directive to specify the name.

GlobalUtility

Base class for a globally registered utility. Unless you use the direct directive to indicate that the class itself should be registered as a utility, the class will automatically be instantiated, therefore the constructor may not take any arguments. Use the implements directive to specify which interface the utility provides, or if that is not unambiguous, also use the provides directive to specify which of the implemented interfaces should be used when registering the utility. If it’s a named utility, you may use the name directive to specify the name.

Context

Subclasses of this will automatically be found as potential contexts for adapters and other types of context-dependent components.

Class-level directives

implements(iface1, iface2, ...)

declares that a class implements the interfaces iface1, iface2, etc.

context(iface_or_class)

declares the type of object that the adapter (or a similar context-dependent component) adapts. This can either be an interface (in this case all objects providing this interface will be eligible contexts for the adapter) or a class (then only instances of that particular class are eligible).

adapts(iface_or_class1, iface_or_class_2, ...)

declares the types of objects that a multi-adapter adapts.

name(ascii_or_unicode)

declares the name of a named utility, named adapter, etc.

title(ascii_or_unicode)

declares the human-readable title of a component (such as a permission, role, etc.)

provides(iface)

declares the interface that a utility provides (as opposed to potentially multiple interfaces that the class implements).

direct()

declares that a GlobalUtility class should be registered as a utility itself, rather than an instance of it.

baseclass()

declares that a subclass of an otherwise automatically configured component should not be registered, and that it serves as a base class instead.

Module-level directives

global_utility(class, [provides=iface, name=ascii_or_unicode, direct=bool])

registers an instance of class (or class itself, depending on the value of the direct parameter) as a global utility. This allows you to register global utilities that don’t inherit from the GlobalUtility base class.

Function decorators

@adapter(iface_or_class1, iface_or_class2, ...)

registers the function as an adapter for the specific interface.

@implementer(iface_or_class1, iface_or_class2, ...)`

declares that the function implements a certain interface (or a number of certain interfaces). This is useful when a function serves as an object factory, e.g. as an adapter.

@subscribe(iface_or_class1, iface_or_class2, ...)

declares that a function is to be registered as an event handler for the specified objects. Normally, an event handler is simply registered as a subscriber for the event interface. In case of object events, the event handler is registered as a subscriber for the object type and the event interface.

Changes

1.0 (2008-05-01)

• Created grokcore.component in March 2008 by factoring basic component base classes and their directives and grokkers out of Grok.