http://www.perlmonks.org?node_id=952784


in reply to Re^4: RFC: Tutorial: use strict; now what!?
in thread RFC: Tutorial: use strict; now what!?

Thanks for explaining, I didn't know you could do that. BTW when I run that I get "soft=, hard=23"
  • Comment on Re^5: RFC: Tutorial: use strict; now what!?

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Re^6: RFC: Tutorial: use strict; now what!?
by educated_foo (Vicar) on Feb 09, 2012 at 17:10 UTC
    Are you running exactly that program? What version of Perl? This is what I get: 
    $ cat foo2.pl
$foo = 23;
$soft = 'foo';
$hard = \$foo;
print "soft=$$soft, hard=$$hard\n";
$ perl foo2.pl
soft=23, hard=23
$ perl -v

This is perl, v5.10.1 (*) built for i686-cygwin-thread-multi-64int

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[d/l]
      I did change it slightly by adding my (couldn't help myself)
      
user$ cat foo2.pl
my $foo = 23;
my $soft = 'foo'; # soft reference
my $hard = \$foo; # hard reference
print "soft=$$soft, hard=$$hard\n";
user$ perl foo2.pl
soft=, hard=23
user$ perl -v

This is perl 5, version 14, subversion 1 (v5.14.1)
built for darwin-2level

user$ cat foo3.pl
$foo = 23;
$soft = 'foo'; # soft reference
$hard = \$foo; # hard reference
print "soft=$$soft, hard=$$hard\n";
user$ perl foo3.pl
soft=23, hard=23

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      I think I've learnt something about 'my' too!
[reply]
[d/l]
        That's your problem: my makes a variable lexical, and symbolic references only work with dynamic/global variables. BTW, this is also why mixing eval STRING with lexicals is problematic: 
        foobar:perl/blead% perl -le '$y="print \$x"; $z=sub { my $x=23; $y}; e
+val $z->()'

foobar:perl/blead% perl -le '$y="print \$x"; $z=sub { $x=23; $y}; eval
+ $z->()'
23

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