Inheritance Question - Quick and Easy I promise!

[sfc]

If I have a class DatabaseObject that has the follow method:

protected function attribute () {
            
		return get_object_vars($this);
            
        }

 

And I call this method from the class user which extends the DatabaseObject class (i.e. $user->attribute), what will "$this" refer to?  The parent or the child?

 

Thanks!

 

[AbraCadaver]

$this refers to whatever instance you are operating on:

 

$db = new DatabaseObject;
$var1 = $db->attribute(); // $this refers to the $db instance
$db = new UserObject;
$var2 = $user->attribute(); // $this refers to the $user instance

[sfc]

That's exactly what I want it to do.  If I make the method static, will that change?

[Mchl]

Yes it will.

1. There's no $this in static context, you'll need to use self::

2. self:: always refers to a class where the method was defined

[sfc]

Thanks guys...still wrapping my mind around all this.

[Mchl]

And of course there's no point in using get_object_vars on a class

 

Returns an associative array of defined object accessible non-static properties for the specified object in scope. If a property have not been assigned a value, it will be returned with a NULL  value.

[sfc]

So I am a little confused.

 

The user class extends databaseobject so I should be able to call a protected class from the instantiated child right?

 

i.e. $user->save();

 

Where save is protected method in the databaseobject class.

 

But when I just did I got an error saying that I called a protected method.  As soon as I change the save() method to public it worked perfectly.

 

Can someone explain?  Do you need more information?

 

Thanks!

[AbraCadaver]

In this case you want private.  Check this: http://us3.php.net/manual/en/language.oop5.visibility.php

[sfc]

I thought private methods couldn't be called by child classes and protected could but not by anything outside the class or sub-classes.

 

Am I wrong?

[Alex]

You got that error because you're attempting to call it publicly. When a method or property is protected it means you can access it from within the child class, not outside of it.