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From: hawley@adobe.COM (Steve Hawley)
Newsgroups: comp.sys.mac.programmer
Subject: Re: THINK C Suggestions
Message-ID: <7154@adobe.UUCP>
Date: 9 Oct 90 17:14:51 GMT
References: <20912@well.sf.ca.us> <1990Oct7.232419.20984@ida.liu.se> <1990Oct8.154744.15837@nntp-server.caltech.edu> <1990Oct9.020415.16763@eng.umd.edu>
Reply-To: hawley@adobe.UUCP (Steve Hawley)
Organization: Adobe Systems Incorporated, Mountain View
Lines: 45

In article <1990Oct9.020415.16763@eng.umd.edu> russotto@eng.umd.edu (Matthew T. Russotto) writes:
>In article <1990Oct8.154744.15837@nntp-server.caltech.edu> palmer@nntp-server.caltech.edu (David Palmer) writes:
>>Here's a suggestion for the next 'Think C'.  Allow the operator '->>' to
>>dereference handles, just as '->' dereferences pointers.
...
>>(The reason why '->>' should be used instead of '-->' is because it
>>shows up better, and it would not be parsed as a post-decrement
>>greater-than combination.)
 
>No, instead as minus shift right.  You can't win.  If you make a smart
>compiler, you can recognize handles to structs and add the extra de-reference
>automagically-- I'd like to see that (in both THINK and MPW.)


Why can't you win?  Is -> interpretted as "negative greater than"?  Nope.
So why should ->> cause any problems?  It should be recogized
correctly by the tokenizer in the scanner.  This why you can write
expressions like:
	--a---=--a-----a--;
and know that it will be interpretted as:
	--a-- -= --a-- - --a--;
Since the scanner matches the largest token.

Something gross, like:
	a-->>=4;
Would be tokenized as
	a-- >>= 4;

If you offer the token ->> shouldn't you also offer the tokens
->>> and ->>>> and ->>>>> and ->>>>>> and ->>>>>>> etc?  I thought that's
what you got from (*******foo).bar...

Your parser just gets ugly (uglier?).

I, personally, am not for it.  Is there any significant win in the coding?
Admittedly, the Mac uses handles fairly frequently, but I can't see what sort
of win you'd be getting from it in the code generation (especially in Think C
which has no real optimizing pass).

Steve Hawley
hawley@adobe.com
-- 
"I'm sick and tired of being told that ordinary decent people are fed up with
being sick and tired.  I know I'm certainly not, and I'm sick and tired of
begin told that I am." -Monty Python