NAME
Object::Simple::Base - a base class to provide constructor and accessors
SYNOPSIS
package Book;
use base 'Object::Simple::Base';
__PACKAGE__->attr('title');
__PACKAGE__->attr('pages' => 159);
__PACKAGE__->attr([qw/authors categories/] => sub { [] });
__PACKAGE__->class_attr('aaa');
__PACKAGE__->hybrid_attr('bbb');
package main;
use Book;
my $book = Book->new;
print $book->pages;
print $book->pages(5)->pages;
my $my_book = Car->new(title => 'Good Day');
print $book->authors(['Ken', 'Tom'])->authors;Methods
new
A subclass of Object::Simple can call "new", and create a instance. "new" can receive hash or hash ref.
package Book;
use base 'Object::Simple::Base';
package main;
my $book = Book->new;
my $book = Book->new(title => 'Good day');
my $book = Book->new({title => 'Good'});"new" can be overrided to arrange arguments or initialize the instance.
Arguments arrange
sub new {
my ($class, $title, $author) = @_;
my $self = $class->SUPER::new(title => $title, author => $author);
return $self;
}Instance initialization
sub new {
my $self = shift->SUPER::new(@_);
# Initialization
return $self;
}If you use one of "weak", "convert" or "trigger" options, It will be better to initialize attributes.
__PACKAGE__->attr(parent => (weak => 1));
__PACAKGE__->attr(url => (convert => 'URI'));
sub new {
my $self = shift->SUPER::new(@_);
foreach my $attr (qw/parent url/) {
$self->$attr($self->{$attr}) if exists $self->{$attr};
}
return $self;
}This is a little bitter work. "init_attrs" of Object::Simple::Util is useful.
use Object::Simple::Util;
sub new {
my $self = shift->SUPER::new(@_);
Object::Simple::Util->init_attrs($self, qw/parent url/);
return $self;
}attr
Create accessor.
__PACKAGE__->attr('name');
__PACKAGE__->attr([qw/name1 name2 name3/]);A default value can be specified. If array ref, hash ref, or object is specified as a default value, that must be wrapped with sub { }.
__PACKAGE__->attr(name => 'foo');
__PACKAGE__->attr(name => sub { ... });
__PACKAGE__->attr([qw/name1 name2/] => 'foo');
__PACKAGE__->attr([qw/name1 name2/] => sub { ... });Various options can be specified.
__PACKAGE__->attr(name => (default => sub {[]}, type => 'array', deref => 1));class_attr
Create accessor for class variable.
__PACKAGE__->class_attr('name');
__PACKAGE__->class_attr([qw/name1 name2 name3/]);
__PACKAGE__->class_attr(name => 'foo');
__PACKAGE__->class_attr(name => sub { ... });This accessor is called from package, not instance.
Book->title('BBB');Class variables is saved to package variable "$CLASS_ATTRS". If you want to delete the value or check existence, "delete" or "exists" function is available.
delete $Book::CLASS_ATTRS->{title};
exists $Book::CLASS_ATTRS->{title};If This class is inherited, the value is saved to package variable of subclass. For example, Book->title('Beautiful days') is saved to $Book::CLASS_ATTRS->{title}, and Magazine->title('Good days') is saved to $Magazine::CLASS_ATTRS->{title}.
package Book;
use base 'Object::Simple::Base';
__PACKAGE__->class_attr('title');
package Magazine;
use base 'Book';
package main;
Book->title('Beautiful days'); # Saved to $Book::CLASS_ATTRS->{title}
Magazine->title('Good days'); # Saved to $Magazine::CLASS_ATTRS->{title}hybrid_attr
Create accessor for a instance and class variable.
__PACKAGE__->hybrid_attr('name');
__PACKAGE__->hybrid_attr([qw/name1 name2 name3/]);
__PACKAGE__->hybrid_attr(name => 'foo');
__PACKAGE__->hybrid_attr(name => sub { ... });If this accessor is called from a package, the value is saved to $CLASS_ATTRS. If this accessor is called from a instance, the value is saved to the instance.
Book->title('Beautiful days'); # Saved to $CLASS_ATTRS->{title};
my $book = Book->new;
$book->title('Good days'); # Saved to $book->{title};Accessor options
default
Define a default value.
__PACKAGE__->attr(title => (default => 'Good news'));If a default value is array ref, or hash ref, or object, the value is wrapped with sub { }.
__PACKAGE__->attr(authors => (default => sub{ ['Ken', 'Taro'] }));
__PACKAGE__->attr(ua => (default => sub { LWP::UserAgent->new }));Default value can be written by more simple way.
__PACKAGE__->attr(title => 'Good news');
__PACKAGE__->attr(authors => sub { ['Ken', 'Taro'] });
__PACKAGE__->attr(ua => sub { LWP::UserAgent->new });type
Specify a variable type.
__PACKAGE__->attr(authors => (type => 'array'));
__PACKAGE__->attr(country_id => (type => 'hash'));If list is passed to the accessor which type is "array", the list is converted to a array ref.
$book->authors('ken', 'taro'); # ('ken', 'taro') -> ['ken', 'taro']
$book->authors('ken'); # ('ken') -> ['ken']If list is passed to the accessor which type is "hash", the list is converted to a hash ref.
$book->country_id(Japan => 1); # (Japan => 1) -> {Japan => 1}deref
Dereference a array ref or hash ref. "type" optios must be specified with "deref".
__PACKAGE__->attr(authors => (type => 'array', deref => 1));
__PACKAGE__->attr(country_id => (type => 'hash', deref => 1));
my @authors = $book->authors;
my %country_id = $book->country_id;trigger
Define a subroutine, which is called when the value is set. This function is received the instance as first argument, the old value as second argument.
__PACKAGE__->attr(error => (trigger => sub{
my ($self, $old) = @_;
$self->state('error') if $self->error;
}));convert
Convert no blessed scalar value to a instance.
__PACKAGE__->attr(url => (convert => 'URI'));
$book->url('http://somehost'); # convert to a instance of URI.Any subroutine is available to convert the value.
__PACKAGE__->attr(url => (convert => sub{
my $value = shift;
$value = URI->new($value) unless ref $value;
return $value;
}));weak
Weaken a reference.
__PACKAGE__->attr(parent => (weak => 1));clone
Package variable of super class is copied to the class at first access, If the accessor is for class. Package variable is copied to the instance, If the accessor is for instance.
"clone" is available by "class_attr", and "hybrid_attr". This options is generally used with "default" value.
__PACKAGE__->hybrid_attr(contraints => (clone => 'hash', default => sub { {} }));"scalar", "array", "hash" is specified as "clone" options.
Any subroutine for clone is also available.
__PACKAGE__->hybrid_attr(url => (default => sub { URI->new },
clone => sub { shift->clone }));Prototype system
Object::Simple::Base provide a prototype system like JavaScript.
+--------+
| Class1 |
+--------+
|
v
+--------+ +----------+
| Class2 | -> |instance2 |
+--------+ +----------+"Class1" has "title" accessor using "hybrid_attr" with "clone" options.
package Class1;
use base 'Object::Simple::Base';
__PACKAGE__->hybrid_attr(title => (default => 'Good day', clone => 'scalar'));"title" can be changed in "Class2".
package Class2;
use base Class1;
__PACKAGE__->title('Beautiful day');This value is used when instance is created. "title" value is "Beautiful day"
package main;
my $book = Class2->new;
$book->title;This prototype system is very useful to create castamizable class for user.
This prototype system is used in Validator::Custom and DBIx::Custom.
See Validator::Custom and DBIx::Custom.
Export
Can import 'new' method to your package.
package YourClass;
use Object::Simple::Base 'new';Similar module
This module is compatible with Mojo::Base.
If you like Mojo::Base, Object:Simple::Base is good select for you.
Author
Yuki Kimoto, <kimoto.yuki at gmail.com>
Github http://github.com/yuki-kimoto/
I develope this module at http://github.com/yuki-kimoto/Object-Simple
Please tell me bug if you find.
Copyright & license
Copyright 2008 Yuki Kimoto, all rights reserved.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.