A handler is the pluggable piece of a command that handles execution. Each command can have zero or more handlers associated with it (in general), of which only one will be active at any given moment in time. When the command is asked to execute, it will simply pass that request on to its active handler, if any.
This interface is not intended to be extended by clients.
@since 3.0
@deprecated Please use the "org.eclipse.core.commands" plug-in instead.
@see org.eclipse.core.commands.IHandler