net.sf.asyncobjects
Class When<I,R>

java.lang.Object
  net.sf.asyncobjects.When<I,R>

Type Parameters:

I - a type of input value

R - a type of result

All Implemented Interfaces:

ExplicitSharing

Direct Known Subclasses:

AsyncProcess.ProcessWhen, CloseableWrapper.InvalidatingWhen

public abstract class When<I,R>
extends Object
implements ExplicitSharing

When construct support class. The construct is inspired by when/catch/finally exprssion in E programming language. The class is an utility implementation of resolver interface. The class is used by many other control construct to implement more specialized control flows.

Subclasses override the following methods:

resolved(Object)

This method is invoked when argument promise is resolved successfully. This method must be overriden.

bodySmashed(Throwable)

This method is invoked when resolved(Object) fails. By default, it delegates to smashed(Throwable).

smashed(Throwable)

This method is invoked when argument promise is smashed or if bodySmashed(Throwable) is not overriden. resolved(Object) fails.

finallyDo()

Is called when resolved(Object) or smashed(Throwable) finish.

See AsyncUnicastServer for definition of "fails", "finishes", and "finishes successfully".

Nested Class Summary

class	When.InternalArgumentListener This is an internal class.
class	When.InternalBodyPromiseResolver This is an internal class.
class	When.InternalFinallyListenerAfterFault This is an internal class.
class	When.InternalFinallyListenerAfterSuccess This is an internal class.
class	When.InternalResultPromiseResolver This is internal class.

Constructor Summary

When(I p)
A constructor from value.

When(Promise<? extends I> p)
A constructor from promise.

Method Summary

protected Promise<? extends R>	bodySmashed(Throwable problem) This method is called if the method resolved(Object) throws exception or when promise returned from that method is smashed.
protected Promise<?>	finallyDo() This action is called when promise is already either resolved or smashed if this method returns promise, the result promise is not resolved until a promise returned by this method is resolved.
Promise<R>	promise()
protected abstract Promise<? extends R>	resolved(I value) This method is called when promise is overloaded in subclasses.
protected Promise<? extends R>	smashed(Throwable problem) This method is called when argument promise is broken.

Methods inherited from class java.lang.Object

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

Constructor Detail

When

public When(Promise<? extends I> p)

A constructor from promise.

Parameters:

p - promise to listen to

When

public When(I p)

A constructor from value.

Parameters:

p - a possibly unresolved reference to asynchronous service

Method Detail

promise

public Promise<R> promise()

Returns:

a promise that resolves to result of when, it could be got only once

resolved

protected abstract Promise<? extends R> resolved(I value)
                                          throws Throwable

This method is called when promise is overloaded in subclasses.

Parameters:

value - value to which promise had been resolved

Returns:

a value becomes curren result of promise

Throws:

Throwable - if there is a problem

bodySmashed

protected Promise<? extends R> bodySmashed(Throwable problem)
                                    throws Throwable

This method is called if the method resolved(Object) throws exception or when promise returned from that method is smashed. By default the method calls the method smashed(Throwable).

Parameters:

problem - a problem that broken a promise.

Returns:

a value becomes curren result of promise

Throws:

Throwable - if there is a problem

smashed

protected Promise<? extends R> smashed(Throwable problem)
                                throws Throwable

This method is called when argument promise is broken. If method bodySmashed(Throwable) is not overriden, it is also called if the method resolved(Object) throws exception or when promise returned from that method is smashed.

The default implementation returns a smashed promise.

Parameters:

problem - a problem that broken a promise.

Returns:

a value becomes curren result of promise

Throws:

Throwable - if there is a problem

finallyDo

protected Promise<?> finallyDo()
                        throws Throwable

This action is called when promise is already either resolved or smashed if this method returns promise, the result promise is not resolved until a promise returned by this method is resolved. If this method throws exception or promise returned by this method is smashed, the resulting promise is smashed too.

Default implementation returns null.

Returns:

a value becomes curren result of promise

Throws:

Throwable - if there is a problem