Acess child object method from parent?

[Anon]

I have lots of objects that are very similar, and I have one particular method that does the same work on each object, so I created a base class. The thing is, one particular object, in one particular method, needs to have a tiny bit of massaging before the standard work is done.

But I keep getting parse error "call to undefined function". But it is there. I called it earlier in the script outside of the base class.

Here's what I've tried to do, simplified:

I create a base class which, among other things, has a get_val method, which does a lot of stuff. It's the same kind of work for a range of objects.

One particular class needs extra work done in certain cicumstances, so at the beginning of this base class routine, I make a call to a method defined in the child class.

// Base class
class baseobj()
{
[...]
function get_val($field)
{
$this->_val_prep($field); // does object prep manpulation, defined in child class;
[ lots o' work ]
return $value;
}

}

//Child class
class childobj extends baseobj
{

[...]
function _val_prep($field)
{
    if ([work needed test expr])
    {
       [prep work]
    }
}

}

The problem is that this fails to parse. I get a:
Call to undefined function: _val_prep() error.

But the function is clearly there. I can access the method so long I don't descend into the base class. Once there, for some reason, it can't see methods defined in the child class.

If I define the method in the base class, it parses and executes that method. But shouldn't that be overidden if the same-named method exists in the child class?

Am I doing something wrong? Had this been seen before?

Thanks for any help.

[Anon]

Hi..

this may be of help to you, i dont know...

// base class, stored in file Basics.class.php
class Basics
{
var $username;
var $password;

function initBasicVars($username, $password)
{
$this->username = $username;
$this->password = $password;
}
}

// child class
// dont forget to include, if the base class lies in another file.
require 'Basics.class.php';

class Child extends Basics
{
var $gender;

function initVars($username, $password, $gender)
{
$this->initBasicVars($username, $password);
$this->gender = $gender;
}
}

[Anon]

I forgot, you must define the
_val_prep($field) method in the BASE CLASS, or it wont find it...

[Anon]

Well, here was what I did to get the desired results, though I still thing I may be setting myself up to run into a big brick wall down the road.

It is most unfortunate that base methods of extended object can't see or access methods of the child.

In any case, it looks like this:

class baseobj
{
function get_value($param)
{
[do stuff]
return $result;
}

[..]

}

class childobj extends baseobj
{
function get_value($param)
{
[do_stuff]
return parent::get_value($param);
}

}

Using the "parent::" syntax lets me get to the method of the base class that I just overrode. If no special work needs to be done, I just don't override it in the particular class.

fyi.