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Postings from May 2001
Not a problem. \Q means quotemeta, except immediately following
a interpolated identifier. You want to start metaquoting immediately
after a curious interpolation? use \Q\Q.
I have been regularly, since I fingured out how, doing things like
print "the time is now ${\(~~localtime)}[go home!]"; # double-not
"scalar" golf hack
in p6 without "weird brackets" I supposed this becomes
print "the time is now $(+localtime)\Q[go home!]";
Right? So if I wanted to quotemeta this thing so I could let sh have it
safely, what in apo2 is preventing me from writing
print "the time is\Q now < $(+localtime)\Q[go home!] \E";
the only time there's an ambiguity is when the metaquoting starts
immediately
after the stopped variable identifier
print SH "echo the time is now `date` so go $destinations{first}\Q\Q
<$tainted> \E";
perl -le'print "\Q\Q\Q <<\E<\E< \E <"'
\\\\\\\ \\\\\\\<\\\\\\\<\\\<\<\ <
metaquote stacks -- why not use \E instead? it has the same issues, but
has
no effect at all currently, and E is for End_of_interpolble_specifier a lot
more than \Q does.
\Q\E is a safe zero-length noninterpolable in any context however, with
no side effect
Garrett Goebel wrote:
>
> From: Larry Wall [mailto:larry@wall.org]
> > Richard Proctor writes:
> > : In Apocalypse 2, \Q is being used for two things, and I
> > : believe this may be ambiguious.
> > :
> > : It has the current \Quote meaning admitibly \Q{oute} it is
> > : also being proposed for a null token disambiguate context.
> > : As in $foo\Q[bar].
> >
> > Hmm, yes, that's a problem. I'd forgotten about the quotemeta kludge.
> > I'll have to think about it. Maybe quotemeta becomes \qm{}
> > or some such.
>
> The problem with \Q quotemeta was the biggest thing to jump out at me when
> reading A2... That is before my brain turned to mush. Seems like quotemeta
> be serving its purpose if you have to consider escaping its contents...
> What's the Perl6 equivalent to:
>
> #!perl -w
> # script.pl:
> my ($match, $filename) = @ARGV;
> local $/;
> open FH, $filename;
> $file = <FH>;
> print scalar @{[$file =~ m/(\Q$match\E)/gs]};
> 1;
> __END__
>
> file.txt contents:
> {foo}\E{foo}\E{foo}
>
> > script.pl {foo} file.txt
> 3
> >
--
David Nicol 816.235.1187 dnicol@cstp.umkc.edu
Parse, munge, repeat.
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