X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FMoose%2FManual%2FTypes.pod;h=2b3a5757877eba935c5c00db59a75c84f34f596c;hb=2de18801c55ae2cfac72d6697e797f3875286d83;hp=6fa9753871046b2ffa9d607f4bed51f1999f937a;hpb=636f25f3bcd1033be8cf71f6dd073b95fa3b50f7;p=gitmo%2FMoose.git diff --git a/lib/Moose/Manual/Types.pod b/lib/Moose/Manual/Types.pod index 6fa9753..2b3a575 100644 --- a/lib/Moose/Manual/Types.pod +++ b/lib/Moose/Manual/Types.pod @@ -2,7 +2,7 @@ =head1 NAME -Moose::Manual::Types - Moose's Type System +Moose::Manual::Types - Moose's type system =head1 TYPES IN PERL? @@ -43,6 +43,7 @@ The basic Moose type hierarchy looks like this Int Str ClassName + RoleName Ref ScalarRef ArrayRef[`a] @@ -58,7 +59,7 @@ In practice, the only difference between C and C is conceptual. C is used as the top-level type in the hierarchy. The rest of these types correspond to existing Perl concepts. For -example, a C is anything that Perl thinks looks like a number. An +example, a C is anything that Perl thinks looks like a number, an C is a blessed reference, etc. The types followed by "[`a]" can be parameterized. So instead of just @@ -68,7 +69,7 @@ can even do something like C. The C type deserves a special mention. Used by itself, it doesn't really mean anything (and is equivalent to C). When it is parameterized, it means that the value is either C or the -parameterized type. So C means an integer or C +parameterized type. So C means an integer or C. For more details on the type hierarchy, see L. @@ -78,7 +79,7 @@ L. It's important to realize that types are not classes (or packages). Types are just objects (L objects, to be exact) with a name and a constraint. Moose maintains a -global type registry that lets it convert names like "Num" into the +global type registry that lets it convert names like C into the appropriate object. However, class names I type names. When you define a new class @@ -91,7 +92,7 @@ using Moose, it defines an associated type name behind the scenes: Now you can use C<'MyApp::User'> as a type name: has creator => ( - is => 'rw', + is => 'ro', isa => 'MyApp::User', ); @@ -101,7 +102,7 @@ assumes that any unknown type name passed as the C value for an attribute is a class. So this works: has 'birth_date' => ( - is => 'rw', + is => 'ro', isa => 'DateTime', ); @@ -118,18 +119,18 @@ that the name is a class: isa => 'ArrayRef[DateTime]', ); -Moose will assume that "DateTime" is a class name in both of these +Moose will assume that C is a class name in both of these instances. =head1 SUBTYPES -Moose uses subtypes in its built-in hierarchy. C is a child of -C for example. +Moose uses subtypes in its built-in hierarchy. For example, C is +a child of C. A subtype is defined in terms of a parent type and a constraint. Any -constraints defined by the parent(s) will be checked first, and then -the the subtype's . A value must pass I of these checks to be -valid for the subtype. +constraints defined by the parent(s) will be checked first, followed by +constraints defined by the subtype. A value must pass I of these +checks to be valid for the subtype. Typically, a subtype takes the parent's constraint and makes it more specific. @@ -150,7 +151,7 @@ Here's a simple (and useful) subtype example: Note that the sugar functions for working with types are all exported by L. -=head2 Creating a New Type (That Isn't a Subtype) +=head2 Creating a new type (that isn't a subtype) You can also create new top-level types: @@ -177,16 +178,25 @@ you prefix names with some sort of namespace indicator to prevent these sorts of collisions. For example, instead of calling a type "PositiveInt", call it -"MyApp.Type.PositiveInt". +"MyApp::Type::PositiveInt" or "MyApp::Types::PositiveInt". We +recommend that you centralize all of these definitions in a single +package, C, which can be loaded by other classes in your +application. + +Once you're doing this, you should almost certainly look at the +L extension which allows easy declaration of type libraries +and can export your types as perl constants so that you can refer to them +as just + + has 'counter' => (is => 'rw', isa => PositiveInt); -Type names are just strings. We recommend that you I use "::" -as a separator in type names. This can be very confusing, because -class names are I valid type names! Using something else, like a -period, makes it clear that "MyApp::User" is a class and -"MyApp.Type.PositiveInt" is a Moose type defined by your application. +rather than needing to fully qualify them everywhere. It also allows -The C module lets you create bareword aliases to longer -names and also automatically namespaces all the types you define. + has 'counts' => (is => 'ro', isa => HashRef[PositiveInt]); + +and similarly for the union and other syntax discussed below, which +will compile time check your use of names and is generally more robust +than the string type parsing for complex cases. =head1 COERCION @@ -207,12 +217,12 @@ works. Coercions, like type names, are global. This is I reason why it is good to namespace your types. Moose will I try to coerce a value unless you explicitly ask for it. This is done by setting the -C attribute parameter to a true value: +C attribute option to a true value: package Foo; has 'sizes' => ( - is => 'rw', + is => 'ro', isa => 'ArrayRefOfInts', coerce => 1, ); @@ -222,7 +232,7 @@ C attribute parameter to a true value: This code example will do the right thing, and the newly created object will have C<[ 42 ]> as its C attribute. -=head2 Deep Coercion +=head2 Deep coercion Deep coercion is the coercion of type parameters for parameterized types. Let's take these types as an example: @@ -236,7 +246,7 @@ types. Let's take these types as an example: => via { hex $_ }; has 'sizes' => ( - is => 'rw', + is => 'ro', isa => 'ArrayRef[Int]', coerce => 1, ); @@ -306,7 +316,7 @@ with a simple wrapper class: use Moose; has 'handle' => ( - is => 'ro', + is => 'rw', isa => 'FileHandle', ); @@ -344,16 +354,16 @@ subtype of C that only allows the specified values: enum 'RGB' => qw( red green blue ); -This creates a type named C +This creates a type named C. =head1 ANONYMOUS TYPES All of the type creation functions return a type object. This type object can be used wherever you would use a type name, as a parent -type, or as the value for an attribute's C parameter: +type, or as the value for an attribute's C option: has 'size' => ( - is => 'rw', + is => 'ro', isa => subtype 'Int' => where { $_ > 0 }, ); @@ -366,7 +376,7 @@ Moose does not provide any means of validating method parameters. However, there are several MooseX extensions on CPAN which let you do this. -The simplest and least sugary is C. This +The simplest and least sugary is L. This lets you validate a set of named parameters using Moose types: use Moose; @@ -381,11 +391,11 @@ lets you validate a set of named parameters using Moose types: ... } -C also supports coercions. +L also supports coercions. There are several more powerful extensions that support method parameter validation using Moose types, including -C, which gives you a full-blown C +L, which gives you a full-blown C keyword. method morning (Str $name) { @@ -408,7 +418,7 @@ C function exported by L: class_type('MyApp::User') - unless find_type_constraint('MyApp::User') || ; + unless find_type_constraint('MyApp::User'); This sort of "find or create" logic is simple to write, and will let you work around load order issues.