Question

I have come across a few Perl modules that for example look similar to the following code:

package MyPackage;

use strict;
use warnings;
use constant PERL510  => ( $] >= 5.0100 );

require Exporter;

our @ISA = qw(Exporter);  
our @EXPORT = qw( );

{  #What is the significance of this curly brace?

    my $somevar;

    sub Somesub {
      #Some code here 
    }
}

1;

What is the significance of 1; and of the curly braces that enclose the $somevar and the Sub?

Answer 1

1 at the end of a module means that the module returns true to use/require statements. It can be used to tell if module initialization is successful. Otherwise, use/require will fail.

$somevar is a variable which is accessable only inside the block. It is used to simulate “static” variables. Starting from Perl 5.10 you can use keyword state keyword to have the same results:

## Starting from Perl 5.10 you can specify "static" variables directly.
sub Somesub {
    state $somevar;
}