use strict;
use warnings;
use Getopt::Long;

my %options;
my %dispatch = (
    a => \&doA,
    b => \&doB,
    c => \&doC,
);

GetOptions (\%options, 'a:s', 'b:s', 'c:s');

for my $option (keys %options) {
    $dispatch{$option}->($options{$option}) if exists $dispatch{$option};
}


sub doA {
    my ($param) = @_;
    
    print "Hello world\n";
}


sub doB {
    my ($param) = @_;
    
    print "Do da dispatch\n";
}


sub doC {
    my ($param) = @_;
    
    print "mu\n";
}

##</code><code>##

mu
Hello world
Do da dispatch