Re^2: restricting values to a nested datastructure

I installed and tested this autovivification critter on my ActiveState Windows machine. Looks like it works just fine. Although I am a bit puzzled why I didn't need a "use Autovivification;" statement. However this does appear to work and in a lexical context as described in the docs.

#!/usr/bin/perl -w
use strict;
use Data::Dumper;

my %a; 

{
   no autovivification 'exists';
   
   if (exists ( $a{'abd'}->[0] ) )
   { print "yes \n"; } 
   
}

print Dumper \%a; 

if (exists ( $a{'abd'}->[0] ) )
   { print "yes \n"; } 
   
print Dumper \%a;

__END__
$VAR1 = {};
$VAR1 = {
          'abd' => []
        };
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Re^3: restricting values to a nested datastructure by tobyink (Canon) on Dec 14, 2011 at 13:17 UTC
Perl's `no` keyword autoloads the module for you. `use Foo` is an abbreviation for: `BEGIN { require Foo; } Foo->import;` [download] The counterpart `no Foo` is an abbreviation for: `BEGIN { require Foo; } Foo->unimport;` [download] Because `import` and `unimport` are just regular old subs, this means that modules can do their interesting stuff with `no` instead of `use`. It's a cute trick, though can confuse people.	[reply] [d/l] [select]

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Re^3: restricting values to a nested datastructure
by tobyink (Canon) on Dec 14, 2011 at 13:17 UTC

Perl's no keyword autoloads the module for you.

use Foo is an abbreviation for:

BEGIN { require Foo; }
Foo->import;
[download]

The counterpart no Foo is an abbreviation for:

BEGIN { require Foo; }
Foo->unimport;
[download]

Because import and unimport are just regular old subs, this means that modules can do their interesting stuff with no instead of use. It's a cute trick, though can confuse people.

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[d/l]
[select]