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From: EIVERSO@cms.cc.wayne.edu
Newsgroups: comp.sys.mac.hypercard
Subject: Re: Better Re: Why no case statement in HyperTalk?
Message-ID: <1991Jun17.134505.21333@cs.wayne.edu>
Date: 17 Jun 91 13:45:05 GMT
Sender: News@cs.wayne.edu
Organization: Wayne State University
Lines: 45

psych@watserv1.waterloo.edu (R. Crispin - Psychology) writes

>In article <1991Jun14.175048.20051@cs.wayne.edu> EIVERSO@cms.cc.wayne.edu write
>>I'd write it like this:
>>
>>on keyDown
>>  if key = "a" then doThis
>>  if key = "b" then doThat
>>  if key = "c" then doTheOther
>>end keyDown
>>

>This is a slower technique since no matter what value KEY has all 3 statements
>are executed. The only time this is faster is if key is unassigned. A
>better technique is as follows

>on keyDown Key
>  if key = "a" then doThis
>  else if key = "b" then doThat
>  else if key = "c" then doTheOTher
>end keydown

>I ran some tests and this can be up to 25% faster but usually it is 10% faster

If I don't talk may way out of this one, well...
All three statements would not necessarily be executed.
It depends on the handlers messaged in the KeyDown handler.

For instance:
on doThis
  <many things>
  exit to HyperCard --no further processing!
end doThis

Since some of you might think this os a cop-out here's a MUCH BETTER script

on keyDown Key
  --check to see if the key pressed has a handler (either a, b, or c has one)
  if key is in "abc" then do "keyProc" & key
  --calls handlers keyProca, keyProcb, or keyProcc
end keyDown

Hopefully the elegance of this code will save my good name.

--Eric Iverson