#!/usr/bin/perl

use strict;
use warnings;

package Foo::Parse;

sub new {
    my ($self, $name, $action)=@_;
    bless { _name => $name,
            _action => $action }, $self;
}

sub parse {
    my $self=shift;
    $self->{_action}->($self, @_);
}

sub warn {
    my ($self,@msg)=@_;
    warn "[$self->{_name}] @msg\n";
}

package main;

my $fp=Foo::Parse->new( 'FooParser',
    sub {
        my $self=shift;
        local $_=shift;
        s/^\w+:// or
          $self->warn("something wrong!");
        split /,/;
    } );

$fp->parse($_) while <>;

__END__