PHP - Overriding properties

Question

Is there a way to prevent overriding properties in PHP? And if yes - how?

You mean like [public, protected or private](http://php.net/manual/en/language.oop5.visibility.php)? — Jared Farrish, Nov 23 '11 at 23:32
I have a protected property in class Base called pbase (as example) and I want to prevent overriding the property in child classes. — user997379, Nov 23 '11 at 23:36
When I make it private, I can't call it from child classes, but I want to prevent only overriding. — user997379, Nov 23 '11 at 23:38
I think you need a method to retrieve your value, not a plain property. — Jared Farrish, Nov 23 '11 at 23:40

score 4 · Answer 1 · answered Nov 23 '11 at 23:53

4

I think this is what you want:

class A{
    private $a;
    public function __construct(){
        $this->a = 'A';
    }
    public function __get($property){
        return $this->{$property};
    }
}

class B Extends A{
    public function getA(){
        return $this->a;
    }
    public function __get($property){
        return parent::__get($property);
    }
}

$b = new B;
echo $b->getA();

answered Nov 23 '11 at 23:53

dev-null-dweller

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That only works if you want a method instead of a property, and if you control the child class definition. – Jared Farrish Nov 23 '11 at 23:54
No :(. I wan't to call this property AS PROPERTY :D Thanks. – user997379 Nov 23 '11 at 23:59
@user997379 - You're going to have to show how you're needing it implemented; short answer, it doesn't sound possible for a [`final`-like](http://en.wikipedia.org/wiki/Final_%28Java%29) functionality in PHP without using a method. – Jared Farrish Nov 24 '11 at 00:01
Can yo please post some code with explanation where do you want to prevent property from being overridden and how you want to access them? – dev-null-dweller Nov 24 '11 at 00:07
@JaredFarrish comment gave me a hint, if you don't want parent classes to have their own property named just as in base class, it is not possible in the moment (for properties, methods can be `final`). – dev-null-dweller Nov 24 '11 at 00:13
@JaredFarrish: `const` is used for "final" properties, it just has the disadvantage of controlling the visibility as well. – chelmertz Nov 24 '11 at 23:40

score 1 · Accepted Answer · answered Nov 23 '11 at 23:38

1

The only way to do such a thing is playing with __set() in a class. But, __set is only used for non accessible properties.

For public properties, i don't think there is any way to prevent overriding.

You should check out the official documentation: http://fr2.php.net/manual/en/language.oop5.overloading.php

answered Nov 23 '11 at 23:38

Lao

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3

Thanks, but I know what means __set and can't help me, becouse my properties are declared. – user997379 Nov 23 '11 at 23:45
So i don't think what you want to do is possible... Try to find another way: store these protected variables in a private array, and access them using a specific __get – Lao Nov 23 '11 at 23:47
So whatever, I undeclared my properties and ... :) – user997379 Nov 24 '11 at 00:12

score 1 · Answer 3 · answered Nov 23 '11 at 23:47

1

class TheBaseClass {

  private $nomod = 'foo';

  public function getNoMod() {
     return $this->nomod;
  }
}

class TheChildClass extends TheParentClass {
   public function funcUsesNomod(){
      return 'The value of nomod is '. $this->getNomod();
   }
}

answered Nov 23 '11 at 23:47

prodigitalson

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To be fair to @dev-null-dweller, the OP seems to suggest a method won't work (it must be a property, for some reason). I have given you both upvotes, though. – Jared Farrish Nov 23 '11 at 23:57

score 0 · Answer 4 · edited May 23 '17 at 12:00

0

"Yeah", if you make them constants. See the answers to How to implement a read-only member variable in PHP?, don't skip the comments.

Example:

class user {
  const ALWAYS_ONE = 1;
}

I guess, declaring properties as private also prevents overloading but they are also inaccessible to the descending classes.

edited May 23 '17 at 12:00

Community

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answered Nov 23 '11 at 23:39

chelmertz

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Thanks, but I need to call this property in child classes (it contains object) with a "property interface" – user997379 Nov 23 '11 at 23:41
1

I think @Jared Farrish is right, use a method. (Hard to tell when you don't spell out the full scenario) – chelmertz Nov 23 '11 at 23:48

PHP - Overriding properties

4 Answers4