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Path: utzoo!mnetor!seismo!caip!cbmvax!amiga!bart
From: bart@amiga.UUCP (Barry A. Whitebook)
Newsgroups: net.micro.amiga
Subject: V1.2 version checking....
Message-ID: <1504@amiga.amiga.UUCP>
Date: Thu, 4-Sep-86 13:40:16 EDT
Article-I.D.: amiga.1504
Posted: Thu Sep  4 13:40:16 1986
Date-Received: Fri, 5-Sep-86 06:45:24 EDT
Reply-To: bart@cloyd.UUCP (Barry A. Whitebook)
Organization: Commodore-Amiga Inc., 983 University Ave #D, Los Gatos CA 95030
Lines: 51
Keywords: 1.2 version checking

< eat this line - please! >

this is amiga!bart:

	recent code examples posted to this net have said something to this
	effect...

	" under V1.2 you can do this new thing... "

	followed by code which includes this type of example...

	/***************** start bad example fragment *************************/

	if ((FooBase = OpenLibrary("foo.library", 0)) == NULL)
	{
		my_go_away_and_die_routine("can't open ANY version of foo library");
	}
	else
	{
		do_1.2_thing();
		my_go_away_and_die_routine("did 1.2 thing");
	}

	/***************** stop  bad example fragment *************************/


	Q: Why is this a bad thing? 

	A: Example doesn't check to see whether it is running under v1.2 before
		doing its thing...


	/***************** start better example fragment *************************/

	#define V1_POINT_2	33

	if ((FooBase = OpenLibrary("foo.library", V1_POINT_2)) == NULL)
	{
		my_go_away_and_die_routine("can't open V1.2 version of foo library");
	}
	else
	{
		do_1.2_thing();
		my_go_away_and_die_routine("did 1.2 thing");
	}

	/***************** stop  better example fragment *************************/

	The bottom line: Please check that the poor user who accidentally tries
	to run your software which depends on 1.2 features under V1.1 or V1.0
	doesn't crash their machine.