Re^2: type glob

The following is what I was trying to test out with my first program:

use strict;
use warnings;
use 5.010;

my %h = qw{a 1 b 2};
my @h = (100, 200, 300);
my $h = 10;

*all = \%h;
*all = \@h;
*all = \$h;  #<overwriting that strange variable??>

say ${*all}{a};
say ${*all}[0];
say ${*all};

--output:--
1
100
10
[download]

It demonstrates that a type glob has "slots" for each perl type that can be assigned to the same variable name, in this case a hash, an array, and a scalar. There are also slots for subroutines, etc. Then when you dereference the glob, which has many references stored in it, the glob dereferences the correct reference based on the context. In the example, the first dereference involves a hash subscript, {a}, so the glob chooses the hash reference and dereferences that. The second dereference involves an array subscript, [0], so the glob dereferences the array reference, etc. Glob is smart.

No news to you, obviously. :)

Comment on Re^2: type glob Download Code

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Re^3: type glob by Khen1950fx (Canon) on Nov 17, 2009 at 20:03 UTC
Just out of curiosity, I ran your script with B::Deparse. That's what I love about Perl---there's always more than one way to do it:-): `#!/usr/bin/perl sub BEGIN { use warnings; use strict 'refs'; require 5.01; } use warnings; use strict 'refs'; BEGIN { $^H{'feature_say'} = q(1); $^H{'feature_state'} = q(1); $^H{'feature_switch'} = q(1); } my (%h) = ( 'a', '1', 'b', '2' ); my (@h) = ( 100, 200, 300 ); my $h = 10; all = \%h; all = \@h; all = \$h; say ${ all; }{'a'}; say ${ all; }[0]; say ${ all; };` [download]	[reply] [d/l]

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Re^3: type glob
by Khen1950fx (Canon) on Nov 17, 2009 at 20:03 UTC

B::Deparse

#!/usr/bin/perl

sub BEGIN {
    use warnings;
    use strict 'refs';
    require 5.01;
}
use warnings;
use strict 'refs';

BEGIN {
    $^H{'feature_say'}    = q(1);
    $^H{'feature_state'}  = q(1);
    $^H{'feature_switch'} = q(1);
}
my (%h) = ( 'a', '1', 'b', '2' );
my (@h) = ( 100, 200, 300 );
my $h   = 10;
*all = \%h;
*all = \@h;
*all = \$h;
say ${ *all; }{'a'};
say ${ *all; }[0];
say ${ *all; };
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