Help with Moose subtype

neilwatson has asked for the wisdom of the Perl Monks concerning the following question:

Greetings Sisters and Brothers, I'm learning Moose. I'm trying to set a subtype type but, having trouble. Please consider the following:

      subtype 'cf_class',
             => as 'Str',
             => where { m/a-zA-Z0-9/ },
             => message { 'Not a valid cf class' };
      has 'class' => {
             is => 'rw',
             isa => 'cf_class'
      };
[download]

I'm getting this error:

Usage: has 'name' => ( key => value, ... ) at /home/neil/perl5/lib/per
+l5/x86_64-linux-thread-multi/Moose.pm line 74.
        Moose::has('Moose::Meta::Class=HASH(0x2b9fe98)', 'class', 'HAS
+H(0x2a9ef98)') called at /home/neil/perl5/lib/perl5/x86_64-linux-thre
+ad-multi/Moose/Exporter.pm line 382
[download]

My desire is to ensure that the parameter 'class' is limited to /a-zA-Z0-9/. What have I done wrong?

Neil Watson
watson-wilson.ca

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