In the past, you may not have thought too much about the difference
between packages and classes, attributes and methods, constructors and
-methods, etc. Part of what the MOP provides is well-defined
-introspection features for each of those things, and in turn Moose
+methods, etc. With Moose, these are all conceptually separate things,
+even though under the hood they're implemented with plain old Perl.
+
+Our meta-object protocol (aka MOP) provides a well-defined
+introspection features for each of those concepts, and Moose in turn
provides I<distinct> sugar for each of them. Moose also introduces
-concepts that are uncommon (or entirely new) like roles, method
-modifiers, and declarative delegation.
+additional concepts such as roles, method modifiers, and declarative
+delegation.
Knowing what these concepts mean in Moose-speak, and how they used to
be done in old school Perl 5 OO is a good way to start learning to use
=head2 Class
-When you say "use Moose" in a package, you are defining your package
-as a class. At its simplest, a class will consist simply of attributes
+When you say "use Moose" in a package, you are making your package a
+class. At its simplest, a class will consist simply of attributes
and/or methods. It can also include roles, method modifiers, and more.
A class I<has> zero or more B<attributes>.
I<opaque> B<object instance>. These properties are accessed through
well-defined accessor methods.
-An attribute is usually analogous to a specific feature of something in
-the class's category. For example, People have first and last
-names. Users have passwords and last login datetimes.
+An attribute is something that the class's members have. For example,
+People have first and last names. Users have passwords and last login
+datetimes.
has 'first_name' => (
is => 'rw',
A role I<has> zero or more B<required methods>.
-A required method is not implemented by the role. Instead, a required
-method says "to use this Role you must implement this method".
+A required method is not implemented by the role. Required methods say
+"to use this Role you must implement this method".
Roles are I<composed> into classes (or other roles). When a role is
composed into a class, its attributes and methods are "flattened" into
=head2 Method Modifiers
-A method modifier is a way of defining an action to be taken when a
-named method is called. Think of it as a hook on the named method. For
-example, you could say "before calling C<login()>, call this modifier
-first". Modifiers come in different flavors like "before", "after",
-"around", and "augment", and you can apply more than one modifier to
-a single method.
+A method modifier is a hook that is called when a named method is
+called. For example, you could say "before calling C<login()>, call
+this modifier first". Modifiers come in different flavors like
+"before", "after", "around", and "augment", and you can apply more
+than one modifier to a single method.
Method modifiers are often used as an alternative to overriding a
method in a parent class. They are also used in roles as a way of
=head2 Delegation
Moose attributes provide declarative syntax for defining
-delegations. A delegation is a method which delegates the real work to
-some attribute of the class.
-
-You saw this in the User example, where we defined a delegation for
-the C<date_of_last_login()> method. Under the hood, this simple calls
-C<date()> on the User object's C<last_login> attribute.
+delegations. A delegation is a method which calls some method on an
+attribute to do its real work.
=head2 Constructor
5 OO code, check out L<Moose::Unsweetened>. This might be helpful for
quickly wrapping your brain around some aspects of "the Moose way".
-Obviously, the first thing to read is the L<Moose::Manual>
+Obviously, the next thing to read is the rest of the L<Moose::Manual>.
After that we recommend that you start with the L<Moose::Cookbook>. If
you work your way through all the recipes under the basics section,
projects / gitmo/Moose.git / blobdiff