#!/usr/bin/perl

use strict;
use warnings;

use constant {
    ATTRIBUTE_0 => 'foo',
    ATTRIBUTE_1 => 'bar'
};


open IN, 'input.xml' or die 'unable to open input XML file';

while (<IN>) {
    print "attribute 0=\t$1\n" if m/@{ATTRIBUTE_0}='(.*)'/e;
    print "attribute 1=\t$1\n" if m/@{ATTRIBUTE_1}='(.*)'/e;
}

close IN;