# Package org.eclipse.core.commands.common

Application programming interfaces for common base classes.

## Package Specification

This package provides some common base classes and exceptions that are used in one or more packages elsewhere. Nothing in this package is intended to be directly subclassed, or used. The code here only supports code in other packages.

Interface Summary
IIdentifiable: An object that is unique identifiable based on the combination of its class and its identifier.

Class Summary
AbstractBitSetEvent: An event that carries with it two or more boolean values.
AbstractHandleObjectEvent: An event fired from a `NamedHandleObject`.
AbstractNamedHandleEvent: An event fired from a `NamedHandleObject`.
EventManager: A manager to which listeners can be attached.
HandleObject: An object that can exist in one of two states: defined and undefined.
HandleObjectManager: A manager of `HandleObject` instances.
NamedHandleObject: A handle object that carries with it a name and a description.
NamedHandleObjectComparator: Comparator for instances of `NamedHandleObject` for display to an end user.

Exception Summary
CommandException: Signals that an exception occured within the command architecture.
NotDefinedException: Signals that an attempt was made to access the properties of an undefined object.