5 Moose::Manual::BestPractices - Get the most out of Moose
9 Moose has a lot of features, and there's definitely more than one way
10 to do it. However, we think that picking a subset of these features
11 and using them consistently makes everyone's life easier.
13 Of course, as with any list of "best practices", these are really just
14 opinions. Feel free to ignore us.
16 =head2 C<no Moose> and immutabilize
18 We recommend that you end your Moose class definitions by removing the
19 Moose sugar and making your class immutable.
25 # extends, roles, attributes, etc.
31 __PACKAGE__->meta->make_immutable;
35 The C<no Moose> bit is simply good code hygiene, and making classes
36 immutable speeds up a lot of things, most notably object construction.
38 =head2 Always call C<SUPER::BUILDARGS>
40 If you override the C<BUILDARGS> method in your class, make sure to
41 play nice and call C<SUPER::BUILDARGS> to handle cases you're not
42 checking for explicitly.
44 The default C<BUILDARGS> method in L<Moose::Object> handles both a
45 list and hashref of named parameters correctly, and also checks for a
46 I<non-hashref> single argument.
48 =head2 Don't use the C<initializer> feature
50 Don't know what we're talking about? That's fine.
52 =head2 Use C<builder> instead of C<default> most of the time
54 Builders can be inherited, they have explicit names, and they're just
57 However, I<do> use a default when the default is a non-reference,
58 I<or> when the default is simply an empty reference of some sort.
60 Also, keep your builder methods private.
62 =head2 Use C<lazy_build>
64 Lazy is good, and often solves initialization ordering problems. It's
65 also good for deferring work that may never have to be done. If you're
66 going to be lazy, use I<lazy_build> to save yourself some typing and
69 =head2 Consider keeping clearers and predicates private
71 Does everyone I<really> need to be able to clear an attribute?
72 Probably not. Don't expose this functionality outside your class
75 Predicates are less problematic, but there's no reason to make your
76 public API bigger than it has to be.
78 =head2 Default to read-only, and consider keeping writers private
80 Making attributes mutable just means more complexity to account for in
81 your program. The alternative to mutable state is to encourage users
82 of your class to simply make new objects as needed.
84 If you I<must> make an attribute read-write, consider making the
85 writer a separate private method. Narrower APIs are easy to maintain,
86 and mutable state is trouble.
88 =head2 Think twice before changing an attribute's type in a subclass
90 Down this path lies great confusion. If the attribute is an object
91 itself, at least make sure that it has the same interface as the type
92 of object in the parent class.
94 =head2 Use L<MooseX::AttributeHelpers> instead of C<auto_deref>
96 The C<auto_deref> feature is a bit troublesome. Directly exposing a
97 complex attribute is ugly. Instead, consider using
98 L<MooseX::AttributeHelpers> to define an API that exposes those pieces
99 of functionality that need exposing. Then you can expose just the
100 functionality that you want.
102 =head2 Namespace your types
104 Use some sort of namespacing convention for type names. We recommend
105 something like "MyApp.Type.Foo". I<Never> use "::" as the namespace
106 separator, since that overlaps with actual class names.
108 =head2 Coercion instead of unions
110 Consider using a type coercion instead of a type union. This was
111 covered at length in L<Moose::Manual::Types>.
113 =head2 Define all your types in one module
115 Define all your types and coercions in one module. This was also
116 covered in L<Moose::Manual::Types>.
120 Dave Rolsky E<lt>autarch@urth.orgE<gt>
122 =head1 COPYRIGHT AND LICENSE
124 Copyright 2009 by Infinity Interactive, Inc.
126 L<http://www.iinteractive.com>
128 This library is free software; you can redistribute it and/or modify
129 it under the same terms as Perl itself.