agi.foundation.tracking

(agi.foundation.tracking-2023r2.jar)

Class EntityDescriptor<TEntity>

java.lang.Object

agi.foundation.infrastructure.DefinitionalObject

agi.foundation.infrastructure.ExtensibleObject

agi.foundation.tracking.EntityDescriptor<TEntity>

Type Parameters:

TEntity - The type of entity.

All Implemented Interfaces:

ICloneWithContext, IEnumerateDependencies, IEquatableDefinition, IFreezable, IServiceProvider

public class EntityDescriptor<TEntity>
extends ExtensibleObject

Describes a family of entities. Generally, each user-defined entity class has one instance of a class derived from EntityDescriptor associated with it. The Default (get / set) property specifies the default descriptor to be used with an entity type.

Constructor Summary

Constructors

Modifier	Constructor and Description
	EntityDescriptor() Initializes a new instance.
protected	EntityDescriptor(EntityDescriptor<TEntity> existingInstance, CopyContext context) Initializes a new instance as a copy of an existing instance.

Method Summary

Modifier and Type	Method and Description
protected boolean	checkForSameDefinition(EntityDescriptor<TEntity> other) Checks to determine if another instance has the same definition as this instance and returns true if it does.
protected boolean	checkForSameDefinition(ExtensibleObject other) Checks to determine if another instance has the same definition as this instance and returns true if it does.
Object	clone(CopyContext context) Clones this object using the specified context.
protected int	computeCurrentDefinitionHashCode() Computes a hash code based on the current properties of this object.
<TDescriptorService> TDescriptorService	get(TypeLiteral<TDescriptorService> typeLiteralTDescriptorService) Gets the specified service from this entity descriptor.
static <TEntity> EntityDescriptor<TEntity>	getDefault(TypeLiteral<TEntity> typeLiteralTEntity) Gets the default descriptor for this type of entity.
static <TEntity> void	setDefault(TypeLiteral<TEntity> typeLiteralTEntity, EntityDescriptor<TEntity> value) Sets the default descriptor for this type of entity.

Methods inherited from class agi.foundation.infrastructure.ExtensibleObject

checkForSameDefinition, enumerateDependencies, freezeAggregatedObjects, getExtensions, getService

Methods inherited from class agi.foundation.infrastructure.DefinitionalObject

areSameDefinition, areSameDefinition, areSameDefinition, areSameDefinition, areSameDefinition, collectionItemsAreSameDefinition, collectionItemsAreSameDefinition, collectionItemsAreSameDefinition, dictionaryItemsAreSameDefinition, freeze, getCollectionHashCode, getCollectionHashCode, getCollectionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDefinitionHashCode, getDictionaryHashCode, getIsFrozen, isSameDefinition, throwIfFrozen

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

EntityDescriptor

public EntityDescriptor()

Initializes a new instance.

EntityDescriptor

protected EntityDescriptor(@Nonnull
                           EntityDescriptor<TEntity> existingInstance,
                           @Nonnull
                           CopyContext context)

Initializes a new instance as a copy of an existing instance.

See ICloneWithContext.clone(CopyContext) for more information about how to implement this constructor in a derived class.

Parameters:

existingInstance - The existing instance to copy.

context - A CopyContext that controls the depth of the copy.

Throws:

ArgumentNullException - Thrown when existingInstance or context is null.

Method Detail

clone

public Object clone(CopyContext context)

Clones this object using the specified context.

This method should be implemented to call a copy constructor on the class of the object being cloned. The copy constructor should take the CopyContext as a parameter in addition to the existing instance to copy. The copy constructor should first call CopyContext.addObjectMapping(T, T) to identify the newly constructed instance as a copy of the existing instance. It should then copy all fields, using CopyContext.updateReference(T) to copy any reference fields.

A typical implementation of ICloneWithContext:

public static class MyClass implements ICloneWithContext {
    public MyClass(MyClass existingInstance, CopyContext context) {
        context.addObjectMapping(existingInstance, this);
        someReference = context.updateReference(existingInstance.someReference);
    }

    @Override
    public final Object clone(CopyContext context) {
        return new MyClass(this, context);
    }

    private Object someReference;
}

In general, all fields that are reference types should be copied with a call to CopyContext.updateReference(T). There are a couple of exceptions:

1. Fields that are aggregate parts of the object should always be copied. A referenced object is an aggregate if properties or methods on the object being copied can modify the externally-visible value of the referenced object.
2. If the semantics of the referenced object require that it have a single parent, owner, context, etc., and the object being copied is that parent, owner, or context, then the referenced object should always be copied.

If one of these exceptions applies, the CopyContext should be given an opportunity to update the reference before the reference is copied explicitly. Use CopyContext.updateReference(T) to update the reference. If CopyContext.updateReference(T) returns the original object, indicating that the context does not have a replacement registered, then copy the object manually by invoking a Clone method, a copy constructor, or by manually constructing a new instance and copying the values.

alwaysCopy = context.updateReference(existingInstance.alwaysCopy);
if (existingInstance.alwaysCopy != null && alwaysCopy == existingInstance.alwaysCopy) {
    alwaysCopy = (AlwaysCopy) existingInstance.alwaysCopy.clone(context);
}

If you are implementing an evaluator (a class that implements IEvaluator), the IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) method shares some responsibilities with the copy context constructor. Code duplication can be avoided by doing the following:

1. For references to other evaluators ONLY, simply assign the reference in the constructor instead of calling CopyContext.updateReference(T). You should still call CopyContext.updateReference(T) on any references to non-evaluators.
2. Call IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) as the last line in the constructor and pass it the same CopyContext passed to the constructor.
3. Implement IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) as normal. See the reference documentation for IEvaluator.updateEvaluatorReferences(agi.foundation.infrastructure.CopyContext) for more information on implementing that method.

public MyClass(MyClass existingInstance, CopyContext context) {
    super(existingInstance, context);
    someReference = context.updateReference(existingInstance.someReference);
    evaluatorReference = existingInstance.evaluatorReference;
    updateEvaluatorReferences(context);
}

@Override
public void updateEvaluatorReferences(CopyContext context) {
    evaluatorReference = context.updateReference(evaluatorReference);
}

@Override
public Object clone(CopyContext context) {
    return new MyClass(this, context);
}

private Object someReference;
private IEvaluator evaluatorReference;

Specified by:

clone in interface ICloneWithContext

Overrides:

clone in class ExtensibleObject

Parameters:

context - The context to use to perform the copy.

Returns:

A new instance which is a copy of this object.

checkForSameDefinition

protected final boolean checkForSameDefinition(ExtensibleObject other)

Checks to determine if another instance has the same definition as this instance and returns true if it does. Derived classes MUST override this method and check all new fields introduced by the derived class for definitional equivalence. It is NOT necessary to check base class fields because the base class will already have done that. When overriding this method, you should NOT call the base implementation because it will return false for all derived-class instances. Derived classes should check the type of other to preserve the symmetric nature of IEquatableDefinition.isSameDefinition(java.lang.Object).

Overrides:

checkForSameDefinition in class ExtensibleObject

Parameters:

other - The other instance to compare to this one.

Returns:

true if the two objects are defined equivalently; otherwise false.

checkForSameDefinition

protected boolean checkForSameDefinition(EntityDescriptor<TEntity> other)

Checks to determine if another instance has the same definition as this instance and returns true if it does. Derived classes MUST override this method and check all new fields introduced by the derived class for definitional equivalence. It is NOT necessary to check base class fields because the base class will already have done that. When overriding this method, you should NOT call the base implementation because it will return false for all derived-class instances. Derived classes should check the type of other to preserve the symmetric nature of IEquatableDefinition.isSameDefinition(java.lang.Object).

Parameters:

other - The other instance to compare to this one.

Returns:

true if the two objects are defined equivalently; otherwise false.

computeCurrentDefinitionHashCode

protected int computeCurrentDefinitionHashCode()

Computes a hash code based on the current properties of this object. Derived classes MUST override this method and compute a hash code that combines: a unique hash code seed, the base implementation result, and the hash codes of all new fields introduced by the derived class which are used in the EntityDescriptor.checkForSameDefinition(agi.foundation.infrastructure.ExtensibleObject) method.

Overrides:

computeCurrentDefinitionHashCode in class ExtensibleObject

Returns:

The computed hash code.

get

@Nonnull
public final <TDescriptorService> TDescriptorService get(TypeLiteral<TDescriptorService> typeLiteralTDescriptorService)

Gets the specified service from this entity descriptor.

Type Parameters:

TDescriptorService - The type of the service to retrieve.

Parameters:

typeLiteralTDescriptorService - A TypeLiteral object representing the generic type TDescriptorService.

Returns:

The requested service.

Throws:

ServiceNotAvailableException - The specified service is not provided by this entity descriptor.

getDefault

@Nonnull
public static <TEntity> EntityDescriptor<TEntity> getDefault(TypeLiteral<TEntity> typeLiteralTEntity)

Gets the default descriptor for this type of entity.

Parameters:

typeLiteralTEntity - A TypeLiteral object representing the generic type TEntity.

setDefault

public static <TEntity> void setDefault(TypeLiteral<TEntity> typeLiteralTEntity,
                                        @Nonnull
                                        EntityDescriptor<TEntity> value)

Sets the default descriptor for this type of entity.

Parameters:

typeLiteralTEntity - A TypeLiteral object representing the generic type TEntity.