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From: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Newsgroups: comp.lang.perl
Subject: Re: Crock involving $^
Message-ID: <11412@jpl-devvax.JPL.NASA.GOV>
Date: 12 Feb 91 20:38:38 GMT
References: <1991Feb12.180057.20540@uvaarpa.Virginia.EDU>
Reply-To: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 50

In article <1991Feb12.180057.20540@uvaarpa.Virginia.EDU> worley@compass.com writes:
: Here's a patch to make $^ behave somewhat more civilly.  When it is
: installed, $^ only absorbs the next character if it is a letter or one
: of @[\]^_.  That should fix most of the strange behavior.  This still
: leaves the ambiguity in $^^ (it is interpreted as "variable
: control-^), but that can be lived with.
: 
: *** toke.c.orig	Tue Feb 12 11:43:22 1991
: --- toke.c	Tue Feb 12 11:46:09 1991
: ***************
: *** 1466,1472 ****
:   	else
:   	    d[1] = '\0';
:       }
: !     if (*d == '^' && !isspace(*s))
:   	*d = *s++ & 31;
:       return s;
:   }
: --- 1466,1473 ----
:   	else
:   	    d[1] = '\0';
:       }
: !     if (*d == '^' &&
: ! 	(('@' <= *s && *s <= '_') || ('a' <= *s && *s <= 'z')))
:   	*d = *s++ & 31;
:       return s;
:   }

Beware.  4.0 will only allow A-Z and [\]^_?.  Notice no @ or lower case.
I'd have to rewrite the symbol table code to allow an identifier containing
a null, and I don't fancy doing that right now.  It's restricted to upper
case so's I can just say *s ^ 64, me being lazy and all.  The lines read:

    if (*d == '^' && (isupper(*s) || index("[\\]^_?",*s)))
	*d = *s++ ^ 64;

: Root Boy Jim writes:
:    On a PDP-11, I would guess that $^f would be the switch register.
: 
: TECO fiend!  But since Perl claims Basic-Plus as one of its
: (illegitimate) parents, it sounds reasonable.  I remember that the
: only peek that didn't require privileges was PEEK(-56), which returned
: the switch register...

Yep.  Did you ever try writing a run-time system with no documentation?
That was fun.  Disassembling the operating system helped, a little.

"Who stomped on my FIRQB?!!??!!"

Larry