What is tie and tied variables in Perl?

In Perl, tie is a feature that allows you to associate a variable with a package that defines how the variable behaves. This means that you can create complex data structures—like hashes, arrays, or even scalars—that interact with the application in customized ways. Tied variables enable you to manipulate the semantics of standard variables, providing you with more control over their behavior.

A tied variable is effectively a regular variable that interacts with a class or object. When you tie a variable, you define a package that will handle the operations performed on that variable, such as fetching or storing data. This is done through overriding built-in methods.

Here's a basic example of using tied variables in Perl:


        package Tie::HashExample;

        use Tie::Hash;
        use strict;
        use warnings;

        our @ISA = qw(Tie::Hash);

        sub TIEHASH {
            my $class = shift;
            my %hash = @_;
            return bless \%hash, $class;
        }

        sub STORE {
            my ($self, $key, $value) = @_;
            print "Storing $key with value $value\n";
            $self->{$key} = $value;
        }

        sub FETCH {
            my ($self, $key) = @_;
            return $self->{$key};
        }

        package main;

        tie my %hash, 'Tie::HashExample';
        $hash{'foo'} = 'bar';  # Stores "bar" with key "foo"
        print $hash{'foo'};     # Fetches and prints "bar"

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What is tie and tied variables in Perl?

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What is tie and tied variables in Perl?

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