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org.eclipse.emf.transaction
Interface TransactionChangeDescription
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All Superinterfaces:
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ChangeDescription,
EObject,
Notifier
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All Known Implementing Classes:
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CommandChangeDescription,
CompositeChangeDescription
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public interface TransactionChangeDescription
- extends
ChangeDescription
A specialized change description that may not be able to apply itself,
especially in the case where it includes non-EMF changes that are not
reversible.
When a transaction rolls back, the assumption is that all changes that it
performed can be undone, even any non-EMF changes that are captured in its
TransactionChangeDescription. This assumption is necessary because
the semantics of rollback guarantee that rollback cannot fail: rollback
must restore the system to the state it was in before the
transaction started. Thus, any change description (possibly nested in a
composite) that cannot be applied will be ignored and a best effort made to
apply all other changes.
However, the same should not hold for undo/redo of the changes performed
by a transaction after it has committed. If the transaction's change
description is stored on some kind of "command stack" as an encapsulation of
an undoable change, then the possibility that a change description cannot
be applied should be respected by disabling undo/redo.
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Method Summary
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boolean
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canApply
()
Queries whether I can
apply my changes. |
boolean
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isEmpty
()
Queries whether I have no changes. |
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Methods inherited from interface org.eclipse.emf.ecore.
EObject
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eAllContents,
eClass,
eContainer,
eContainingFeature,
eContainmentFeature,
eContents,
eCrossReferences,
eGet,
eGet,
eIsProxy,
eIsSet,
eResource,
eSet,
eUnset
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canApply
boolean canApply()
- Queries whether I can
apply my changes.
If I can, then it is assumed that I could
reverse them also.
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-
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Returns:
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true if my changes can be applied;
false otherwise (i.e., they are not invertible)
isEmpty
boolean isEmpty()
- Queries whether I have no changes.
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Returns:
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true if I have no changes (applying me would have
no effect on anything); false, otherwise
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