PHP: rfc:class_properties_initialization

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====== Request for Comments: Class properties initialization ======
  * Version: 1.0
  * Date: 20010-07-30
  * Author: Krzysztof Antczak <k.antczak@livedata.pl>
  * Status: In Draft
  * First Published at: http://wiki.php.net/rfc/class_properties_initialization
  * Related RFC: [[rfc:annotations]], [[rfc:returntypehint]]

===== Introduction =====

The purpose of this feature is to provide more advanced way to initialize class properties using closures, objects, type hinting.

==== Why do we need it? ====

  * **code readability**

===== Proposal =====

**Main idea**

<code php>
class Foo
{
    private $var1 = function () { /* some callback ? */ }

    private $var2 = array ( 'foo' => function () { /* some callback ? */ } );

    private httpRequest $var3 = NULL;
}
</code>

instead of:

<code php>
class Foo
{
    private $var1;

    private $var2;

    private $var3 = NULL;

    public function __construct ()
    {
        $this -> var1 = function () { /* some callback ? */ }
        
        $this -> var2 = array ( 'foo' => function () { /* some callback ? */ } );

        if ( ( $request = SomeCore :: getRequest () ) instanceof httpRequest )
        {
            $this -> var3 = $request;
        }
    }
}
</code>

**Other / Related**

* objects structures - structured objects initialization - like IoC/DI containers, where structure is not a result of code execution, but it's a result of strictly controlled design.

<code php>
class Foo
{
    private $var1 = new Bar();

    private $var2 = Bar :: getInstance ();
}
</code>

* initialization with functions

<code php>
class Foo
{
    private $var1 = time ();
    
    private httpRequest $var2 = getRequest ();
}
</code>

===== Rejected initialization types =====

<code php>
private $foo = $this -> someStuff(); // impossible/nonsense (?)
</code>

===== Changelog =====

2010-07-30 k.antczak Initial RFC creation.
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