Array::Each::Tutorial 0.02

Array::Each::Tutorial - POD giving various examples how to use Array::Each.

SYNOPSIS

man Array::Each
man Array::Each::Tutorial

or

perldoc Array::Each
perldoc Array::Each::Tutorial

Overview

This tutorial contains only POD, so dont do this:

use Array::Each::Tutorial; # dont do this

Rather, simply read the POD (as you are doing). But first, please read the docs for Array::Each, because the whole scoop is there.

This tutorial is intended to augment those docs with examples showing situations where you might want to use Array::Each instead of other techniques.

EXAMPLES

Parallel Arrays vs. Using a Hash

First of all, use a hash. Its almost always the best solution if you want to associate a "key" with a "value". And there are modules available that will let you do wonderful things with hashes, like keeping the keys sorted or keeping them in the order they were added.

So given a hash, you might at some point want to do this:

my %h = ( a=>1, b=>2, c=>3, d=>4, e=>5 );
while( my( $k, $v ) = each %h ) {
# ... do something with $k and $v ...
}

On the other hand, if parallel arrays better implement your algorithm, then you may find you want to do something like this:

my @k = qw( a b c d e );
my @v = qw( 1 2 3 4 5 );
for my $i ( 0 .. $#k ) {
my( $k, $v ) = ( $k[$i], $v[$i] );
# ... do something with $k and $v (and maybe $i) ...
}

Using Array::Each, you could do the same thing this way:

use Array::Each;
my @k = qw( a b c d e );
my @v = qw( 1 2 3 4 5 );
my $obj = Array::Each->new( @k, @v );
while( my( $k, $v, $i ) = $obj->each ) {
# ... do something with $k and $v (and maybe $i) ...
}

If you dont need $i at all, you can leave it out, e.g.,

while( my( $k, $v ) = $obj->each ) {
# ... do something with $k and $v ...
}

If you have more than two parallel arrays, include them all in the call to new() and add as many "capture" variables as you need, e.g.,

my @k = qw( a b c d e );
my @v = qw( 1 2 3 4 5 );
my @p = qw( - + ~ = : );
my $obj = Array::Each->new( @k, @v, @p );
while( my( $k, $v, $p, $i ) = $obj->each ) {
# ... do something with $k, $v, and $p (and maybe $i) ...
}