SYNOPSIS

package Foo::Bar;

use Moose;
use MooseX::MungeHas "is_ro";

has foo => (); # read-only
has bar => (is => "rw"); # read-write

DESCRIPTION

MooseX::MungeHas alters the behaviour of the attributes of your Moo, Moose or Mouse based class. It manages to support all three because it doesn't attempt to do anything smart with metathingies; it simply installs a wrapper for "has" that munges the attribute specification hash before passing it on to the original "has" function.

The following munges are always applied (simply because I can see no sensible reason why you would not want them to be).

• Implement "is => "rwp"" and "is => "lazy"" in Moose and Mouse.

  (These already work in Moo.)

• Implement "builder => 1", "clearer => 1", "predicate => 1", and "trigger => 1" in Moose and Mouse.

  (These already work in Moo.)

• Implement "builder => sub { ... }" in Moose and Mouse.

  (This already works in Moo.)

• Allow Moo to support "coerce => 0|1" for Type::Tiny type constraints. (Moo normally expects a coderef for the coercion.)

  (These already work in Moose and Mouse, and has actually been added to Moo as of version 1.006000.)

• Makes "has $name => sub { ... }" into a shortcut for:

     has $name => (is => "lazy", builder => sub { ... });
  

• Makes "has $name => $type_constraint" into a shortcut for:

     has $name => (isa => $type_constraint);
  

  (Assuming that $type_constraint is a blessed type constraint object a la Type::Tiny, MooseX::Types, etc.)

When you import this module (i.e. "use MooseX::MungeHas") you can provide a list of additional mungers you want it to apply. These may be provided as coderefs, though for a few common, useful sets of behaviour, there are pre-defined shortcut strings.

   # "no_isa" is a pre-defined shortcut;
   # the other munger is a coderef.
   #
   use MooseX::MungeHas "no_isa", sub {
      # Make constructor ignore private attributes
      $_{init_arg} = undef if /^_/;
   };

Within coderefs, the name of the attribute being processed is available in the $_ variable, and the specification hash is available as %_.

You may provide multiple coderefs.

The following are the pre-defined shortcuts:

"is_ro", "is_rw", "is_rwp", "is_lazy"

These mungers supply defaults for the "is" option.

"always_coerce"

Automatically provides "coerce => 1" if the type constraint provides coercions. (Unless you've explicitly specified "coerce => 0".)

"no_isa"

Switches off "isa" checks for attributes, unless they coerce.

"simple_isa"

Loosens type constraints if they don't coerce, and if it's likely to make them significantly faster. (Loosening "Int" to "Num" won't speed it up.)

Only works if you're using Type::Tiny constraints.

Mungers provided as coderefs are executed after predefined ones, but are otherwise executed in the order specified.

Multiple Wrappers

Since version 0.007, it has been possible to use MooseX::MungeHas to export multiple wrappers with different names:

   package Foo;
   use Moose;
   use MooseX::MungeHas {
      has_ro   => [ "is_ro", "always_coerce" ],
      has_rw   => [ "is_rw", "always_coerce" ],
   };
   
   has_ro "foo" => (required => 1);
   has_rw "bar";

Note in the example above, MooseX::MungeHas has installed two brand new wrapped "has" functions with different names, but it has left the standard "has" function unmolested.

If you wanted to alter the standard function too, then you could use:

   package Foo;
   use Moose;
   use MooseX::MungeHas {
      has      => [          "always_coerce" ],
      has_ro   => [ "is_ro", "always_coerce" ],
      has_rw   => [ "is_rw", "always_coerce" ],
   };
   
   has_ro "foo" => (required => 1);
   has_rw "bar";

AUTHOR

Toby Inkster <[email protected]>.

COPYRIGHT AND LICENCE

This software is copyright (c) 2013-2014 by Toby Inkster.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.

DISCLAIMER OF WARRANTIES

THIS PACKAGE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.