解决方法

#!/usr/bin/perl

use strict;
use warnings;
use 5.010;

sub fields {
  say 'this is fields';
}

sub another {
  say 'this is another subroutine';
}

my %functions = (
  fields  => \&fields,another => \&another,);

my $function = shift;

if (exists $functions{$function}) {
  $functions{$function}->();
} else {
  die "There is no function called $function available\n";
}

一些例子：

$./dispatch_tab fields
this is fields
$./dispatch_tab another
this is another subroutine
$./dispatch_tab xxx
There is no function called xxx available