[sf-perl] the mouse with antlers

Joseph Brenner doom at kzsu.stanford.edu
Wed Apr 4 17:38:53 PDT 2012

I've been messing about with Mouse.pm of late (a lightweight Moose
substitute whose star may already be fading), and I've got a basic

I'm used to doing href based objects with an init routine that's
called by new, where I can do any initialization I might need to do.
In Moose land I find myself doing things like this:

use Moose
has name        =>
     (is => 'rw',  isa => 'Str', required => 1);
has subject     =>
     (is => 'rw',  isa => 'Str', default => sub{ 'Report about .
$_[0]->name }, lazy => 1);
has id              =>
     (is => 'rw',  isa => 'Str', default => sub{  lookup( $_[0]->name
) },          lazy => 1);

Where the "lazy" setting delays the use of the initialization code to
the time when the field is first accessed, and that way I can be
certain that the name field has settled down.

I find myself worrying about what I would do if I needed more than two
stages, instantiation and lazy access.  Like what if I wanted to put
the id in the subject?
I'd have to do a gratuitous access of id to make sure it was defined
before accessing subject...

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