agi.foundation.infrastructure

(agi.foundation.core-2024r2.jar)

Class CalculationContextFacet

java.lang.Object

agi.foundation.infrastructure.CalculationContextFacet

All Implemented Interfaces:

ICloneWithContext, IThreadAware

Direct Known Subclasses:

CentralBodiesFacet, LeapSecondsFacet

public abstract class CalculationContextFacet
extends Object
implements IThreadAware

A facet of a CalculationContext.

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
abstract Object	clone(CopyContext context) Clones this object using the specified context.
abstract boolean	getIsThreadSafe() Gets a value indicating whether the methods on this instance are safe to call from multiple threads simultaneously.
abstract void	useInCurrentContext() Adds this instance to the current context, making it the official instance of this facet type in the context.

Methods inherited from class java.lang.Object

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

Constructor Detail

CalculationContextFacet

protected CalculationContextFacet()

Initializes a new instance.

CalculationContextFacet

protected CalculationContextFacet(@Nonnull
                                  CalculationContextFacet 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 abstract 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

Parameters:

context - The context to use to perform the copy.

Returns:

A new instance which is a copy of this object.

getIsThreadSafe

public abstract boolean getIsThreadSafe()

Gets a value indicating whether the methods on this instance are safe to call from multiple threads simultaneously.

If this property is true, all methods and properties are guaranteed to be thread safe. Conceptually, an object that returns true for this method acts as if there is a lock protecting each method and property such that only one thread at a time can be inside any method or property in the class. In reality, such locks are generally not used and are in fact discouraged. However, the user must not experience any exceptions or inconsistent behavior that would not be experienced if such locks were used.

If this property is false, the behavior when using this class from multiple threads simultaneously is undefined and may include inconsistent results and exceptions. Clients wishing to use multiple threads should call CopyForAnotherThread.copy(T) to get a separate instance of the object for each thread.

Specified by:

getIsThreadSafe in interface IThreadAware

useInCurrentContext

public abstract void useInCurrentContext()

Adds this instance to the current context, making it the official instance of this facet type in the context.