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pub/Smalltalk/gnu_st/exceptions/CATALOG-CARD
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	NAME		Exeptions
        AUTHOR          mckelvey@eso.mc.xerox.com
        FUNCTION        Ability to raise exceptions and define handlers for them
        ST-VERSIONS     GNU 1.1.1
	PREREQUISITES	None
	THEN FILE IN	
	CONFLICTS WITH	
	DISTRIBUTION  	world
	VERSION	ID	1.0
	VERSION DATE	26 Apr 95
	SUMMARY

	This directory contains the Smalltalk source Exceptions.st and
        documentation in Exceptions.txt which describes the usage.
        The classes in Exceptions.st provide a mechanism to create an
        exception object, called an ExceptionEvent.  Raising an exception
        is done by send the raise or raiseWith: message to an ExceptionEvent
        instance.  A raised exception may be handled in an exception block,
        which is created by the following expression:

        ExceptionEvent 
            on: exceptionEvent1 handle: handler1 
            { on: exceptionEvent2 handle: handler2 }
            { on: exceptionEvent3 handle: handler3 } 
            { on: exceptionEvent4 handle: handler4 }
            { onAnyOther: otherHandler }
            do: aBlock

        where the selectors enclosed in { } are optional.  First, aBlock
        is invoked with no arguments.  If it sends raise or raiseWith: to
        the ExceptionEvent exceptionEvent1, the block handler1 is invoked
        with one argument, an ExceptionValue.  If exceptionEvent2 is raised,
        handler2 is invoked, and so on.  If an ExceptionEvent is raised 
        other than those listed in an on:handle: pair, the handler 
        otherHandler is invoked, passing the ExceptionValue argument.
        For more details, see the documentation in Exceptions.txt.        

						Curt McKelvey - 4-26-95