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Re: #\EOF ... Yes, again.
- To: ALAN at MIT-MC, LISP-FORUM at MIT-MC
- Subject: Re: #\EOF ... Yes, again.
- From: Daniel L. Weinreb <dlw at MIT-AI>
- Date: Fri ,26 Sep 80 12:25:00 EDT
- Sender: dlw at CADR2 at MIT-AI
From: Alan Bawden <ALAN at MIT-MC>
A character is something that you can put in strings and pnames. You
can TYO it. You can hold down the meta key and type it. #\eof fits
none of these descriptions. So it must be that #\eof isn't a
character. This makes it different from everything else that a
#\<foo> can be.
This is what my mail yesterday was about. The enf-of-file indicator
is not a character, but it is in the same name space as characters,
and therefore it really IS elegant to use a \# construct. See yesterday's
letter for details.
Argument: All TYI's and TYIPEEK's return -1 at eof; why not
just use that?
Answer: (1) All TYI's and TYIPEEK's return #o101 for "A" being
typed, but #/A was thought to be more readable.
Do I believe what I read here? I thought that you wanted to have #/
and #\ return character objects. And I thought that you wanted to
write code that workes on an EBCDIC machine?
No, you miss his point; he is being sarcastic, saying that you should no
more depend on the -1 than you should on the 101, even if all
implementations now are the same, because there might be different ones
in the future.
Nobody will ever make this mistake (making -1 a character) and live.
It doesn't matter; it is inelegant to depend on it.
Golly gee, the Lisp Machine Manual really doesn't document the -1. What
do you know...