NAME

Object::Simple - Simplest class builder, Mojo::Base porting, fast and less memory

Simplest class builder. All you learn is only has function!
Mojo::Base porting. Do you like Mojolicious? If so, this is good choices!
Fast and less memory. Fast new and accessor method. Memory saving implementation.

SYNOPSIS

package SomeClass;
use Object::Simple -base;

# Create accessor
has 'foo';

# Create accessor with default value
has foo => 1;
has foo => sub { [] };
has foo => sub { {} };
has foo => sub { OtherClass->new };

# Create accessors at once
has [qw/foo bar baz/];
has [qw/foo bar baz/] => 0;

Create object.

# Create a new object
my $obj = SomeClass->new;
my $obj = SomeClass->new(foo => 1, bar => 2);
my $obj = SomeClass->new({foo => 1, bar => 2});

# Set and get value
my $foo = $obj->foo;
$obj->foo(1);

# set-accessor can be changed
$obj->foo(1)->bar(2);

Inheritance

# Foo.pm
package Foo;
use Object::Simple -base;

# Bar.pm
package Bar;
use Foo -base;

# Bar.pm (another way to inherit)
package Bar;
use Object::Simple -base => 'Foo';

DESCRIPTION

Object::Simple is Simplest class builder. All you learn is only has function. You can learn all features of Object::Simple in an hour. There is nothing difficult.

Do you like Mojolicious? In fact, Object::Simple is Mojo::Base porting. Mojo::Base is basic class builder in Mojolicious project. If you like Mojolicious, this is good choice. If you have known Mojo::Base, you learn nothing.

new and accessor method is fast. Implementaion is pure perl and save instructions as possible. Memory is saved. Extra objects is not created at all. Very light-weight object-oriented module.

Comparison with Class::Accessor::Fast

Class::Accessor::Fast is simple, but lack often used features. new method can't receive hash arguments. Default value can't be specified. If multiple values is set through the accessor, its value is converted to array reference without warnings.

Comparison with Moose

Moose has very complex syntax and depend on much many modules. You have to learn many things to do object-oriented programing. Understanding source code is difficult. Compile-time is very slow and memory usage is very large. Execution speed is not fast. For simple OO, Moose is overkill. Moo is improved in this point.

TUTORIAL

1. Create class and accessor

At first, you create class.

package SomeClass;
use Object::Simple -base;

By using -base option, SomeClass inherit Object::Simple and import has method.

Object::Simple have new method. new method is constructor. new method can receive hash or hash reference.

my $obj = SomeClass->new;
my $obj = SomeClass->new(foo => 1, bar => 2);
my $obj = SomeClass->new({foo => 1, bar => 2});

Create accessor by using has function.

has 'foo';

If you create accessor, you can set or get attribute value.s

# Set value
$obj->foo(1);

# Get value
my $foo = $obj->foo;

set-accessor can be changed.

$obj->foo(1)->bar(2);

You can define default value.

has foo => 1;

If foo attribute value is not exists, default value is used.

my $foo_default = $obj->foo;

If you want to use reference or object as default value, default value must be surrounded by code reference. the return value become default value.

has foo => sub { [] };
has foo => sub { {} };
has foo => sub { SomeClass->new };

You can create multiple accessors at once.

has [qw/foo bar baz/];
has [qw/foo bar baz/] => 0;

2. Override method

Method can be overridden.

Example:

Initialize the object

sub new {
  my $self = shift->SUPER::new(@_);
  
  # Initialization
  
  return $self;
}

Example:

Change arguments of new.

sub new {
  my $self = shift;
  
  $self->SUPER::new(x => $_[0], y => $_[1]);
  
  return $self;
}

You can pass array to new method.

my $point = Point->new(4, 5);

3. Examples - class, accessor, inheritance and method overriding

I introduce Object::Simple example.

Point class: two accessor x and y, and clear method to set x and y to 0.

package Point;
use Object::Simple -base;

has x => 0;
has y => 0;

sub clear {
  my $self = shift;
  
  $self->x(0);
  $self->y(0);
}

Use Point class.

use Point;
my $point = Point->new(x => 3, y => 5);
print $point->x;
$point->y(9);
$point->clear;

Point3D class: Point3D inherit Point class. Point3D class has z accessor in addition to x and y. clear method is overridden to clear x, y and z.

package Point3D;
use Point -base;

has z => 0;

sub clear {
  my $self = shift;
  
  $self->SUPER::clear;
  
  $self->z(0);
}

Use Point3D class.

use Point3D;
my $point = Point->new(x => 3, y => 5, z => 8);
print $point->z;
$point->z(9);
$point->clear;

4. What is Object-Oriented programing?

I introduce concepts of Object-Oriented programing.

Inheritance

I explain the essence of Object-Oriented programing.

First concept is inheritance. Inheritance means that if Class Q inherit Class P, Class Q use all methods of class P.

+---+
| P | Base class
+---+   have method1 and method2
  |
+---+
| Q | Sub class
+---+   have method3

Class Q inherits Class P, Q can use all methods of P in addition to methods of Q.

In other words, Q can use method1, method2, and method3

You can use -base option to inherit class.

# P.pm
package P;
use Object::Simple -base;

sub method1 { ... }
sub method2 { ... }

# Q.pm
package Q;
use P -base;

sub method3 { ... }

Perl have useful functions and methods to help Object-Oriented programing.

If you know what class the object is belonged to, use ref function.

my $class = ref $obj;

If you know what class the object inherits, use isa method.

$obj->isa('SomeClass');

If you know what method the object(or class) can use, use can method

SomeClass->can('method1');
$obj->can('method1');

Encapsulation

Second concept is encapsulation. Encapsulation means that you don't touch internal data directory. You must use public method when you access internal data.

Create accessor and use it to keep this rule.

my $value = $obj->foo;
$obj->foo(1);

Polymorphism

Third concept is polymorphism. Polymorphism is divided into two concepts, overload and override

Perl programmer don't need to care overload. Perl is dynamic type language. Subroutine can receive any value.

Override means that you can change method behavior in sub class.

# P.pm
package P;
use Object::Simple -base;

sub method1 { return 1 }

# Q.pm
package Q;
use P -base;

sub method1 { return 2 }

P method1 return 1. Q method1 return 2. Q method1 override P method1.

# P method1 return 1
my $obj_a = P->new;
$obj_p->method1; 

# Q method1 return 2
my $obj_b = Q->new;
$obj_q->method1;

If you want to use super class method from sub class, use SUPER pseudo-class.

package Q;

sub method1 {
  my $self = shift;
  
  # Call supper class P method1
  my $value = $self->SUPER::method1;
  
  return 2 + $value;
}

If you understand three concepts, you have learned Object-Oriented programming primary parts.

FUNCTIONS

has

Create accessor.

has 'foo';
has [qw/foo bar baz/];
has foo => 1;
has foo => sub { {} };

Create accessor. has receive accessor name and default value. Default value is optional. If you want to create multiple accessors at once, specify accessor names as array reference at first argument.

If you want to specify reference or object as default value, it must be code reference not to share the value with other objects.

Get and set a attribute value.

my $foo = $obj->foo;
$obj->foo(1);

If a default value is specified and the value is not exists, you can get default value.

If a value is set, the accessor return self object. So you can set a value repeatedly.

$obj->foo(1)->bar(2);

You can create all accessors at once.

has [qw/foo bar baz/];

METHODS

new

my $obj = Object::Simple->new(foo => 1, bar => 2);
my $obj = Object::Simple->new({foo => 1, bar => 2});

Create a new object. new receive hash or hash reference as arguments.

attr

__PACKAGE__->attr('foo');
__PACKAGE__->attr([qw/foo bar baz/]);
__PACKAGE__->attr(foo => 1);
__PACKAGE__->attr(foo => sub { {} });

__PACKAGE__->attr([qw/foo bar baz/]);

Create accessor. attr method usage is equal to has method.

OPTIONS

-base

By using -base option, the class inherit Object::Simple and import has function.

package Foo;
use Object::Simple -base;

has x => 1;
has y => 2;

strict and warnings is automatically enabled.

You can also use -base option in sub class to inherit other class.

# Bar inherit Foo
package Bar;
use Foo -base;

You can also use the following syntax.

# Same as above
package Bar;
use Object::Simple -base => 'Foo';

FAQ

Really enough object-oriented programing with this few features?

Yes, for example, Mojolicious is very big project, but in fact, source code is clean only using single inheritance. Generally speaking, readable source code is build on simple concepts, not complex features.

Object::Simple is fastest OO module?

No, Object::Simple is not fastest module, but enough fast. If you really need performance, you can access hash value directory.

# I want performance in some places. Let's access hash value directory!
$self->{x};

BACKWARDS COMPATIBILITY POLICY

If a functionality is DEPRECATED, you can know it by DEPRECATED warnings. You can check all DEPRECATED functionalities by document. DEPRECATED functionality is removed after five years, but if at least one person use the functionality and tell me that thing I extend one year each time he tell me it.

EXPERIMENTAL functionality will be changed without warnings.

(This policy was changed at 2011/10/22)

DEPRECATED

function exporting of C<new> and C<attr> method # Will be removed 2021/6/1

The syntax of multiple key-value arguments 
  has x => 1, y => 2;      
  __PACAKGE__->attr(x => 1, y => 2);
# Will be removed 2021/6/1

class_attr method # will be removed 2017/1/1
dual_attr method # will be removed 2017/1/1

BUGS

Tell me the bugs by mail or github http://github.com/yuki-kimoto/Object-Simple

AUTHOR

Yuki Kimoto, <kimoto.yuki at gmail.com>

I'm pleasure if you send message for cheer. I can get power by only your messages!

COPYRIGHT & LICENSE

This program is free software; you can redistribute it and/or modify it under the same terms as Artistic v2.

This is same as Mojolicious licence.

USERS

Projects using Object::Simple.

GitPrep - Portable GitHub system into your own server. https://github.com/yuki-kimoto/gitprep
DBIx::Custom - DBI extension to execute insert, update, delete, and select easily
Validator::Custom - HTML form Validation, simple and good flexibility

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`g` `i`	Go to issues
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NAME

SYNOPSIS

DESCRIPTION

TUTORIAL

1. Create class and accessor

2. Override method

3. Examples - class, accessor, inheritance and method overriding

4. What is Object-Oriented programing?

Inheritance

Encapsulation

Polymorphism

FUNCTIONS

has

METHODS

new

attr

OPTIONS

-base

FAQ

Really enough object-oriented programing with this few features?

Object::Simple is fastest OO module?

BACKWARDS COMPATIBILITY POLICY

DEPRECATED

BUGS

AUTHOR

COPYRIGHT & LICENSE

USERS

SEE ALSO

Module Install Instructions