#46899 [Com]: Typed function arguments should allow nulls

[zyss at mail dot zp dot ua]

 ID:               46899
 Comment by:       zyss at mail dot zp dot ua
 Reported By:      zyss at mail dot zp dot ua
 Status:           Open
 Bug Type:         Feature/Change Request
 Operating System: Irrelevant
 PHP Version:      5.2.8
 New Comment:

Example in more readable form:

  class ExElement extends Exception { };

  class Element {
    // each element references document for fast access
    protected /* Document */ $document;
    protected /* Element */ $parent;

    function __construct(
      Document $document,
      Element $parent = null) /* throws ExElement */
    {
      // is still checked to be valid Document object reference
      $this->document = $document;

      if ($parent && ($parent->getDocument() != $document))
        throw new ExElement("Parent's document doesn't match " .
          "Element constructor's argument", 1);
      $this->parent = $parent;
    }

    function getDocument() {
      return $this->document;
    }
  }


Previous Comments:
------------------------------------------------------------------------

[2008-12-18 13:33:55] zyss at mail dot zp dot ua

Description:
------------
Currently class type can be specified as function argument type, but it
is frequently required to pass null instead of object reference when
there is a default argument value set and it is null. In the following
example constructor's $parent argument can be null for the top-level
objects, but current PHP version doesn't allow it to be null forcing to
remove type declaration that is very undesirable:

  class ExElement extends Exception { };

  class Element {
    protected /* Document */ $document; // each element references
document for fast access
    protected /* Element */ $parent;

    function __construct(Document $document, Element $parent = null) /*
throws ExElement */ {
      $this->document = $document; // is still checked by PHP to be
valid Document object reference
      if ($parent && ($parent->getDocument() != $document))
        throw new ExElement("Parent's document doesn't match Element
constructor's argument", 1);
      $this->parent = $parent;
    }

    function getDocument() {
      return $this->document;
    }
  }



------------------------------------------------------------------------


-- 
Edit this bug report at http://bugs.php.net/?id=46899&edit=1