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Postings from May 2012
On Tue May 15 10:48:24 2012, doy@tozt.net wrote:
> On Tue, May 15, 2012 at 10:37:58AM -0700, Jim Avera wrote:
> > 'use strict' does not catch undeclared variables in the newer ${^NAME}
> > syntax.
> >
> > For example ${^BOGUS} and ${^_BOGUS} are silently accepted.
> >
> > #!/usr/bin/perl
> > use strict; use warnings;
> >
> > for my $varname ('BOGUS', '{BOGUS}', '{^_BOGUS}', '{^BOGUS}') {
> > my $stmt = "my \$x = \$$varname;";
> > eval $stmt;
> > print $@;
> > if ($@) {
> > print "Compile error: $stmt\n";
> > } else {
> > print "NO error: $stmt\n";
> > }
> > }
>
> Variables that begin with ^ are special to perl, and reserved. You
> shouldn't be using them in your own code anyway.
Except for ${^_...}. perlvar says:
No
control-character name that begins with C<^_> will acquire a special
meaning in any future version of Perl; such names may therefore be
used safely in programs. C<$^_> itself, however, I<is> reserved.
> They are like
> punctuation variables in that they are always global, and always
> reference the variable in the main:: package. For instance:
>
> package Foo;
> $BAR = 1;
> package Bar;
> say $BAR ? "yes" : "no";
>
> prints "no", while
>
> package Foo;
> ${^BAR} = 1;
> package Bar;
> say ${^BAR} ? "yes" : "no";
>
> prints "yes". This is all by design. 'strict' doesn't catch accesses
> like this for the same reason that it doesn't catch accesses to things
> like $@.
Indeed, perlvar continues:
Perl identifiers that begin with digits, control characters, or
punctuation characters are exempt from the effects of the C<package>
declaration and are always forced to be in package C<main>; they are
also exempt from C<strict 'vars'> errors.
--
Father Chrysostomos
---
via perlbug: queue: perl5 status: open
https://rt.perl.org:443/rt3/Ticket/Display.html?id=112952
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