class can not inherit from another class, why ?

[lawrence]

Is this a valid class definition?

class McBase {

// 06-14-04 - I may or may not later add something here. This will
// be the top of the PDS content management system hierarchy. I'm
// leaving it blank for now but want it here for future flexibility.

}




I use it later on this line:

class McBasic extends McBase {


but I get this error:

Fatal error: Class mcbasic: Cannot inherit from undefined class mcbase
in /usr/local/www/vhosts/publicpen.com/htdocs/designer/ppKernel/McBasic.php
on line 5

[Michael Fesser]

Re: class can not inherit from another class, why ?

.oO(lawrence)
[color=blue]
>Is this a valid class definition?
>
>class McBase {
>[...][/color]

Yes.
[color=blue]
>I use it later on this line:
>
>class McBasic extends McBase {
>
>
>but I get this error:
>
>Fatal error: Class mcbasic: Cannot inherit from undefined class mcbase
>in /usr/local/www/vhosts/publicpen.com/htdocs/designer/ppKernel/McBasic.php
>on line 5[/color]

The question is: Are both classes stored in the same file? Apparently
not. So you have to include the base-class before you can extend it,
e.g.

require_once 'mcbase.php';

class McBasic extends McBase {...}

HTH
Micha

[lawrence]

Re: class can not inherit from another class, why ?

Michael Fesser <netizen@gmx.ne t> wrote in message[color=blue][color=green]
> >Fatal error: Class mcbasic: Cannot inherit from undefined class mcbase
> >in /usr/local/www/vhosts/publicpen.com/htdocs/designer/ppKernel/McBasic.php
> >on line 5[/color]
>
> The question is: Are both classes stored in the same file? Apparently
> not. So you have to include the base-class before you can extend it,
> e.g.
>
> require_once 'mcbase.php';[/color]



Thanks. Now I got it working. But McBasic doesn't seem to have its
constructor called when it is the parent of another class. I've been
trying to test, as you'll see here:

class McBasic extends McBase {


var $controllerForA ll = null;
var $resultsObject = null;
var $notifyObject = null;
var $historyObject = null;



/**
*
*
* 06-14-04 - most objects in the PDS content management system should
be
* descended from McBasic. This provides basic servies to all its
child
* classes. All the classes that themselves contain no other objects
can
* safely be put here, and then become services available to all child
* classes.
*
*
*
*
*/
function McBasic() {
// a test for debugging
echo "hello<br>" ;
$this->controllerForA ll = & getController() ;

if (is_object($thi s->controllerForA ll)) {
echo "this is an object";
} else {
echo "this is not an object";
}


$this->resultsObjec t = &
$this->controllerForA ll->getObject("McR esults", " in the constructor
of McBasic.");
$this->notifyObject = &
$this->controllerForA ll->getObject("McN otify", " in the constructor of
McBasic.");
$this->historyObjec t = &
$this->controllerForA ll->getObject("McH istory", " in the constructor
of McBasic.");
}
}









But in the class McArrangements, I have this line:

class McArrangements extends McBasic {

Yes McArrangements throws an error whenever I use the 4 objects that
are set in the constructor of McBasic. The error says that there is no
such object. For instance, I get an error on this line in
McArrangements:

$this->resultsObjec t->error("In setControlPanel CbId(), in the class
McArrangements, we expected the method's parameter to be a number, but
instead we got this: $cbId ", "McArrangements ");


So I decided to write a test for McBasic, and the test revealed that
everything was working for McBasic. In the test, I call McBasic
directly, and at the end of the constructor I test to see if
$this->resultsObjec t is an object. It tests true. Yet when I refer to
$this->resultsObjec t in McArrangements, I get "No such object". How
can this be?

[Berislav Lopac]

Re: class can not inherit from another class, why ?

lawrence wrote:[color=blue]
> Thanks. Now I got it working. But McBasic doesn't seem to have its
> constructor called when it is the parent of another class. I've been
> trying to test, as you'll see here:[/color]

<snip>
[color=blue]
> So I decided to write a test for McBasic, and the test revealed that
> everything was working for McBasic. In the test, I call McBasic
> directly, and at the end of the constructor I test to see if
> $this->resultsObjec t is an object. It tests true. Yet when I refer to
> $this->resultsObjec t in McArrangements, I get "No such object". How
> can this be?[/color]

Are you using PHP5? Try using _construct().

According to the Zend articles, the old way of defining constructors should
work as well, but there might be some problems when calling parent's
contructor.

Berislav

[Berislav Lopac]

Re: class can not inherit from another class, why ?

Berislav Lopac wrote:[color=blue]
> lawrence wrote:[color=green]
>> Thanks. Now I got it working. But McBasic doesn't seem to have its
>> constructor called when it is the parent of another class. I've been
>> trying to test, as you'll see here:[/color]
>
> <snip>
>[color=green]
>> So I decided to write a test for McBasic, and the test revealed that
>> everything was working for McBasic. In the test, I call McBasic
>> directly, and at the end of the constructor I test to see if
>> $this->resultsObjec t is an object. It tests true. Yet when I refer to
>> $this->resultsObjec t in McArrangements, I get "No such object". How
>> can this be?[/color]
>
> Are you using PHP5? Try using _construct().[/color]

Oops, that should be __construct() (two underscores).

Berislav

[Phil Powell]

Re: class can not inherit from another class, why ?

lkrubner@geocit ies.com (lawrence) wrote in message news:<da7e68e8. 0407271336.3076 66a9@posting.go ogle.com>...[color=blue]
> Michael Fesser <netizen@gmx.ne t> wrote in message[color=green][color=darkred]
> > >Fatal error: Class mcbasic: Cannot inherit from undefined class mcbase
> > >in /usr/local/www/vhosts/publicpen.com/htdocs/designer/ppKernel/McBasic.php
> > >on line 5[/color]
> >
> > The question is: Are both classes stored in the same file? Apparently
> > not. So you have to include the base-class before you can extend it,
> > e.g.
> >
> > require_once 'mcbase.php';[/color]
>
>
>
> Thanks. Now I got it working. But McBasic doesn't seem to have its
> constructor called when it is the parent of another class. I've been
> trying to test, as you'll see here:[/color]

[snip]

If you're running PHP 4+ and not PHP 5 use the parent keyword to run
the parent's constructor in the child's constructor:

[PHP]
class Parent {

function Parent() {
// DO STUFF HERE
}

}

class Child extends Parent {

function Child() {
parent::Parent( );
}

}
[/PHP]

Phil

[lawrence]

Re: class can not inherit from another class, why ?

soazine@erols.c om (Phil Powell) wrote in message news:<1cdca2a7. 0407281516.a2b7 d2e@posting.goo gle.com>...[color=blue]
> lkrubner@geocit ies.com (lawrence) wrote in message news:<da7e68e8. 0407271336.3076 66a9@posting.go ogle.com>...[color=green]
> > Michael Fesser <netizen@gmx.ne t> wrote in message[color=darkred]
> > > >Fatal error: Class mcbasic: Cannot inherit from undefined class mcbase
> > > >in /usr/local/www/vhosts/publicpen.com/htdocs/designer/ppKernel/McBasic.php
> > > >on line 5
> > >
> > > The question is: Are both classes stored in the same file? Apparently
> > > not. So you have to include the base-class before you can extend it,
> > > e.g.
> > >
> > > require_once 'mcbase.php';[/color]
> >
> >
> >
> > Thanks. Now I got it working. But McBasic doesn't seem to have its
> > constructor called when it is the parent of another class. I've been
> > trying to test, as you'll see here:[/color]
>
> [snip]
>
> If you're running PHP 4+ and not PHP 5 use the parent keyword to run
> the parent's constructor in the child's constructor:
>
> [PHP]
> class Parent {
>
> function Parent() {
> // DO STUFF HERE
> }
>
> }
>
> class Child extends Parent {
>
> function Child() {
> parent::Parent( );
> }
>
> }
> [/PHP]
>
> Phil[/color]

The parent keyword! I'd never heard of that! That is a terrific tip,
thanks much.

I got it work like this: McArrangements had a constructor that wasn't
doing much, just setting a variable that could be set elsewhere. So I
rewrote it and deleted the constructor. Suddenly the constructor of
McBasic was called. So, I reasoned, if you want to have the
constructor of a parent class called, you are not allowed to have a
constructor in the child class. But now I see that, quite reasonably,
there is a way to call parent constructors, and still have the child
have a constructor. Very good!