DomainObject
This is a simple class that signifies classes that extend it are a
DomainObject. In a more practical sense
it offers a properties
implementation, that is lacking from PHP., (*1)
Why
We believe in a plain old php objects (POPO) for modelling your domain. These
objects should hold no logic other than their core values. A DomainObject
should have a direct link to an entity in your Universe of Discourse., (*2)
This class helps you do that in a generic way. It has some niceties such as
support for accessing your properties through both functions and object
property notation. But mostly, it is a strong signal that the class that's
extending it is, in fact, a DomainObject., (*3)
Why not simply rely on public variables?
Using simple variables like:, (*4)
class Person
{
public $name;
}
Works pretty well for most simple properties., (*5)
Imagine the following though:, (*6)
class Person
{
public $firstName;
public $lastName;
public function getFullName()
{
return $this->firstName . ' ' . $this->lastName;
}
}
In order to get the full name for a person (first + last), you need to write a
method. Now you have to mix both properties and methods in your API. This is
not very consistent and rather inflexible., (*7)
Example
<?php
use Angrybytes\DomainObject;
use \InvalidArgumentException;
class BlogPost extends DomainObject
{
private $title;
private $contents;
public function getTitle()
{
return $this->title;
}
public function setTitle($title)
{
// You can do simple sanity checks in your setters
if (strlen($title) < 3) {
throw new InvalidArgumentException('Title should be 3 or more characters long');
}
$this->title = $title;
return $this;
}
public function getContents()
{
return $this->contents;
}
public function setContents($contents)
{
$this->contents = $contents;
return $this;
}
}
Using this you can:, (*8)
<?php
$post = new BlogPost;
// Set properties
$post
->setTitle('This is the title for my blog post')
->setContents('foo');
// Retrieve properties using property notation
echo $post->title;
echo $post->contents;
// Retrieve data in array form for easy serialization
$json = json_encode(
$post->toArray()
);
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