org.grouplens.grapht.reflect

Interface Satisfaction

All Superinterfaces:

Serializable

All Known Implementing Classes:

ClassSatisfaction, InstanceSatisfaction, NullSatisfaction, ProviderClassSatisfaction, ProviderInstanceSatisfaction

public interface Satisfaction
extends Serializable

A concrete type. It has a set of dependencies which must be satisfied in order to instantiate it. It can also be viewed as an instantiable extension of Type.

Satisfactions are expected to provide a reasonable implementation of Object.equals(Object) and Object.hashCode() so that they can be de-duplicated, etc.

Author:

GroupLens Research

Method Summary

Modifier and Type	Method and Description
CachePolicy	getDefaultCachePolicy() Get the default cache policy for instances created by this satisfaction.
List<Desire>	getDependencies() Get this satisfaction's dependencies.
Class<?>	getErasedType() Get the type-erased class of this satisfaction's type.
Type	getType() Get the type of this satisfaction.
boolean	hasInstance() Query whether this satisfaction already has an instance to return.
Instantiator	makeInstantiator(Map<Desire,Instantiator> dependencies, LifecycleManager lm) Create an instantiator from this satisfaction.
<T> T	visit(SatisfactionVisitor<T> visitor) Visit the satisfaction.

Method Detail

getDependencies

List<Desire> getDependencies()

Get this satisfaction's dependencies.

Returns:

A list of dependencies which must be satisfied in order to instantiate this satisfaction.

getType

Type getType()

Get the type of this satisfaction. If this is a synthetic Satisfaction, then a null type is returned.

Returns:

The type of objects to be instantiated by this satisfaction.

getErasedType

Class<?> getErasedType()

Get the type-erased class of this satisfaction's type. If this is a synthetic Satisfaction, then null is returned.

Returns:

The class object for this satisfaction's type.

hasInstance

boolean hasInstance()

Query whether this satisfaction already has an instance to return. If true, then this satisfaction's provider will just return an instance that is already in existence; if false, then its provider may create new instances.

Returns:

whether the satisfaction already has an instance.

visit

<T> T visit(SatisfactionVisitor<T> visitor)

Visit the satisfaction. This method invokes the appropriate method on the provided visitor to report information on itself.

Type Parameters:

T - The type returned from the visitor.

Parameters:

visitor - The visitor object.

Returns:

The return value from the invoked visitor method.

getDefaultCachePolicy

CachePolicy getDefaultCachePolicy()

Get the default cache policy for instances created by this satisfaction. In most cases this should be NO_PREFERENCE, but annotations such as Singleton can be used to specify a default. BindingFunctions are allowed to overrule the default cache policy.

Returns:

The default cache policy if no function overrules it

makeInstantiator

Instantiator makeInstantiator(@Nonnull
                              Map<Desire,Instantiator> dependencies,
                              @Nullable
                              LifecycleManager lm)

Create an instantiator from this satisfaction.

If the details of the Satisfaction require instantiation (e.g. a class or provider class satisfaction), the returned provider should be a new instance, and it should perform no memoization of its own. Caching is the purview of Injector implementations.

If the satisfaction is configured to use specific instances, this rule is obviously void.

Parameters:

dependencies - A function mapping desires to providers of their instances.

lm - The lifecycle manager (if one should be used).

Returns:

An instantiator of new instances of the type specified by this satisfaction, instantiated using the specified dependency mapping.