org.eclipse.gef4.mvc.operations

Interface ITransactional

All Known Implementing Classes:

ContentPolicy, CreationPolicy, DeletionPolicy, FXBendPolicy, FXChangeViewportPolicy, FXResizeConnectionPolicy, FXResizePolicy, FXTransformConnectionPolicy, FXTransformPolicy

public interface ITransactional

An ITransactional policy consists of an initialization part ( init()) and a commit part (commit()). The policy can be used to manipulate its host in-between those calls. The policy returns an ITransactionalOperation upon commit() which performs the manipulations.

Note, that an ITransactional policy is safe against multiple initialization/commitment in sequence. However, only the first commit() call will return an operation (subsequent calls will return null).

If an ITransactional policy is not initialized, it should throw an IllegalStateException if any of its "work" methods are called.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	ITransactional.NoOperation The ITransactional.NoOperation does not have an effect.
static class	ITransactional.UnexecutableOperation The ITransactional.UnexecutableOperation cannot be executed.

Field Summary

Fields

Modifier and Type	Field and Description
static ITransactionalOperation	NOOP This ITransactionalOperation does not have an effect.
static ITransactionalOperation	UNEXECUTABLE This ITransactionalOperation cannot be executed.

Method Summary

Modifier and Type	Method and Description
ITransactionalOperation	commit() Returns an ITransactionalOperation that performs all manipulations applied by the policy since the last init() call.
void	init() Initializes the policy, so that the policy's "work" methods can be used.

Field Detail

NOOP

static final ITransactionalOperation NOOP

This ITransactionalOperation does not have an effect. It can be returned by commit() if no changes have to be applied.

UNEXECUTABLE

static final ITransactionalOperation UNEXECUTABLE

This ITransactionalOperation cannot be executed.

Method Detail

commit

ITransactionalOperation commit()

Returns an ITransactionalOperation that performs all manipulations applied by the policy since the last init() call. When called multiple times in sequence, only the first call will yield an operation, the subsequent calls will yield null.

You can return NOOP if no changes have to be applied. The domain will filter out all NOOPs before their execution.

You can return UNEXECUTABLE to prevent any composite operation that contains the UNEXECUTABLE from execution.

Returns:

An ITransactionalOperation that performs all manipulations applied by the policy since the last init() call.

init

void init()

Initializes the policy, so that the policy's "work" methods can be used. Calling a "work" method while the policy is not initialized will result in an IllegalStateException. It is safe to call init() multiple times in sequence.