Solved

why is $documentIndocument null?

Posted on 2014-04-23
7
169 Views
Last Modified: 2014-04-23
why is $documentIndocument null?

output:
Document Object
(
    [inDomainObject] => 3
)
User Object
(
    [inUser] => 2
    [inDomainObject] => 1
)
User Object
(
    [inUser] => 2
    [inDomainObject] => 1
)



<?php
abstract class DomainObject {
    public $inDomainObject=1;
    public static function create() {
        return new static();        
    }
}

class User extends DomainObject {
   public $inUser=2;
   public static function inuserstatic(){
     return new static();
   }
}

class Document extends DomainObject {
  public $inDomainObject=3;
  public static function indocument(){
    self::create();
  }
}

echo '<pre>';
$documentCreate=Document::create();
print_r($documentCreate);
$userInuserstatic=User::inuserstatic();
print_r($userInuserstatic);
$userCreate=User::create();
print_r($userCreate);
$documentIndocument=Document::indocument();
print_r($documentIndocument);
echo '</pre>';
?>

Open in new window

0
Comment
Question by:rgb192
  • 4
  • 3
7 Comments
 
LVL 75

Expert Comment

by:käµfm³d 👽
ID: 40018961
Maybe I'm missing something...what is null? Your object appears to have been dumped out via print_r without issue.
0
 

Author Comment

by:rgb192
ID: 40018981
$documentIndocument=Document::indocument();
print_r($documentIndocument);

is null

notice there are 4 variables and only 3 dumps
0
 

Author Comment

by:rgb192
ID: 40018997
<?php
abstract class DomainObject {
    public $inDomainObject=1;
    public static function create() {
        return new static();        
    }
}

class User extends DomainObject {
   public $inUser=2;
   public static function inuserstatic(){
     return new static();
   }
}

class Document extends DomainObject {
  public $inDocumentObject=3;
  public static function indocument(){
    self::create();
  }
}

echo '<pre>';
$documentCreate=Document::create();
print_r($documentCreate);
$userInuserstatic=User::inuserstatic();
print_r($userInuserstatic);
$userCreate=User::create();
print_r($userCreate);
$documentIndocument=Document::indocument();
print_r($documentIndocument);
echo '</pre>';
?>

Open in new window


I change line 17
from
public $inDomainObject=3;
to
public $inDocumentObject=3;

for clarity so we can tell which class was entered.

new output

Document Object
(
    [inDocumentObject] => 3
    [inDomainObject] => 1
)
User Object
(
    [inUser] => 2
    [inDomainObject] => 1
)
User Object
(
    [inUser] => 2
    [inDomainObject] => 1
)
0
Free Tool: Postgres Monitoring System

A PHP and Perl based system to collect and display usage statistics from PostgreSQL databases.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

 
LVL 75

Expert Comment

by:käµfm³d 👽
ID: 40019014
Ah, my mistake. (So I was missing something!) The problem is that you are not returning anything from your method call. Change line 19 to:

return self::create();

Open in new window

0
 

Author Comment

by:rgb192
ID: 40019103
but why doesnt the current line19
self::create();
return line5
which is
return new static();

why do I need to append 'return' to line19 when there is already a 'return' in line5
0
 
LVL 75

Accepted Solution

by:
käµfm³d   👽 earned 500 total points
ID: 40019136
Because each function returns something. A function calling another function doesn't mean that the called function's return value will automatically be returned from the calling function. If you write a function that you want to return values from, then it must have a return itself.
0
 

Author Closing Comment

by:rgb192
ID: 40019181
thanks for teaching me about return values of a function.
0

Featured Post

Networking for the Cloud Era

Join Microsoft and Riverbed for a discussion and demonstration of enhancements to SteelConnect:
-One-click orchestration and cloud connectivity in Azure environments
-Tight integration of SD-WAN and WAN optimization capabilities
-Scalability and resiliency equal to a data center

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

These days socially coordinated efforts have turned into a critical requirement for enterprises.
Password hashing is better than message digests or encryption, and you should be using it instead of message digests or encryption.  Find out why and how in this article, which supplements the original article on PHP Client Registration, Login, Logo…
The viewer will learn how to dynamically set the form action using jQuery.
The viewer will learn how to create a basic form using some HTML5 and PHP for later processing. Set up your basic HTML file. Open your form tag and set the method and action attributes.: (CODE) Set up your first few inputs one for the name and …

860 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question