Nested inheritance in PHP

Question

For an instance, I have classes like this:

class MyClassA{
   protected $variableA='this is var A';
   public $variableB='this is var B';
   //some function here
}

class MyClassB extends MyClassA{
   //some function here
}

class MyClassC extends MyClassB{
   //some function here
}

class MyClassD extends MyClassC{
   //some function here
}

How can I get $variableA and $variableB from MyClassD?

nickb · Accepted Answer · 2012-02-08 03:31:40Z

3

Just reference them in any class using $this.

class MyClassD extends MyClassC {
    function __construct()
    {
        echo $this->variableA; 
        echo $this->variableB;
    }
}

$var = new MyClassD;

See it work!

answered Feb 8, 2012 at 3:31

nickb

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drew010 · Accepted Answer · 2012-02-08 03:44:36Z

1

Since variableA is public in the base class, you can just access it directly like so: $MyClassDObj->variableB.

Since variableA is protected, you need to write a getter if you wanted to access it from outside the class, otherwise from within class D, you can access it just like variableB. A getter would look like this:

public function getVariableA()
{
    return $this->variableA;
}

And then you call $MyClassDObj->getVariableA();

edited Feb 8, 2012 at 3:44

answered Feb 8, 2012 at 3:33

drew010

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6 Comments

nickb Over a year ago

If variableA were private, you'd need a getter. protected does not require a getter.

drew010 Over a year ago

Protected is the same as private except that protected variables are accessible from derived classes, private variables are not, therefore it still requires a getter for access outside the class. php.net/manual/en/language.oop5.visibility.php

nickb Over a year ago

Drew, unfortunately you are mistaken. See my example, no getter required.

drew010 Over a year ago

I know that, but I said if he wanted to access it from outside the class he would need a getter. He didn't really clarify in the question. Sorry if I didn't make that clear.

nickb Over a year ago

OH! My mistake. Then of course you are correct! Referencing these protected variables from outside of the class requires a getter. Sorry.

|

oaziz · Accepted Answer · 2012-02-08 03:32:14Z

0

Just like you'd get it from MyClassA.

answered Feb 8, 2012 at 3:32

oaziz

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