[Resolved] Help! Defined class is undefined!!

ppowell

class OptionsView extends PaginationView {

/**
 * Constructor
 * 
 * @access public
 */
function OptionsView() {}			// CONSTRUCTOR

}

This class exists in the same script as both the parent class PaginationView and its child class AlbumOptionsView.. both AlbumOptionsView and PaginationView seem to exist with no problem, however, if I do this:

class AlbumOptionsView extends OptionsView {
//
}

I get this error:

Fatal error: Class albumoptionsview: Cannot inherit from undefined class optionsview in /catalog/include/classes.inc.php on line 105

Could someone shed some light onto this? How can a class be undefined in the same instance as its parent and child?

Phil

rebelo

There has to be a problem somewhere in your code not defining the the OptionsView class before the AlbumOptionsView class tried to extend it.

I just did this simple code and got no problems with the definitions.

<?php

class PaginationView {
  // the first one  

}   

class OptionsView extends PaginationView {
  // the second one
}   

class AlbumOptionsView extends OptionsView {
  // the third one
}   

echo class_exists("AlbumOptionsView"); // echos 1;
?>

ppowell

This is totally random but perhaps this might be it: using PHP 4.1.2, does the physical order of the classes matter?

class AlbumOptionsView extends OptionsView {

}

class OptionsView extends View {

}

Phil

rebelo

I suppose that's a posibility. I just checked out the php.net documentation for classes and objects in php4 and didn't find anything to that effect. I did just do a test on my own system (php5) and it handles it ok regardless of the order in which the classes are defined.

ppowell

This bombs out in PHP 4.1.2:

/**
  * Options classes using views that will allow for options for components of section views
  *
  * @author Phil Powell
  * @version 1.0.0
  * @package IMAGE_CATALOG
  */
class BlahView extends OptionsView {

function BlahView() {
	print_r("BLAH!");
}

}


/**
  * Options classes using views that will allow for options for components of section views
  *
  * @author Phil Powell
  * @version 1.0.0
  * @package IMAGE_CATALOG
  */
class OptionsView extends PaginationView {

/**
 * Constructor
 * 
 * @access public
 */
function OptionsView() {}			// CONSTRUCTOR

}

Error:

Fatal error: Class blahview: Cannot inherit from undefined class optionsview in /catalog/include/classes.inc.php on line 2841

This, however, works just fine!!


/**
  * Options classes using views that will allow for options for components of section views
  *
  * @author Phil Powell
  * @version 1.0.0
  * @package IMAGE_CATALOG
  */
class OptionsView extends PaginationView {

/**
 * Constructor
 * 
 * @access public
 */
function OptionsView() {}			// CONSTRUCTOR

}


/**
  * Options classes using views that will allow for options for components of section views
  *
  * @author Phil Powell
  * @version 1.0.0
  * @package IMAGE_CATALOG
  */
class BlahView extends OptionsView {

function BlahView() {
	print_r("BLAH!");
}

}

No errors of any kind whatsoever! It would be so simple as to move the class physically BELOW OptionsView then that would be fine, except, that makes absolutely NO sense! Why would order matter with classes physically placed in the exact same script?

Phil

rebelo

Interestingly I also get a warning on that first snipet when I try to extend the class which is defined second. I am very surprised but I guess that's just the way it is. A class cannot extend a class that has not yet been defined.

Will you be able to work around this constraint to solve the problem?

ppowell

I wish it were that simple, but this is going to really melt your brain:


class AlbumOptionsView extends PaginationView {

}

class BlahView extends OptionsView {

}

class OptionsView extends PaginationView {

}

class PaginationView extends View {

}

This scenario will completely fail, but not for the reasons you think. Simply by taking away BlahView everything works, though AlbumOptionsView extends PaginationView which hasn't yet been written until you go further down the same script. But adding BlahView AFTER OptionsView works; adding BlahView BEFORE OptionsView fails, having BlahView extend PaginationView instead of OptionsView, wherever you put it, works as well.

This makes absolutely no sense.

Phil

rebelo

My brain has been melted. That's really strange, man...

I wonder if it could be a bug of some sort...

Perhaps you ought to escalate this to the php mail list.

ppowell

How do I do that without being compared to being "stupid" or "incompetent" as in times past? Or, just plain how do I do that from here?

Thanx
Phil

rebelo

You don't do that from here, you go to www.php.net and then click on mailing lists in the top bar and then subscribe and post your message. If you explain exactly what the problem is and what you have done so far to narrow down the possible explanations, you should be received with helpful feedback.

If you leave out any details or are vague about what you have done, that's what will lead to difficulty dealing with some people.

You can also try the php newsgroup or the php irc channel on freenode, but the mailing list is probably the best solution.

ppowell

To recap:

class AlbumOptionsView extends PaginationView { // THIS WORKS

}

class FooView extends OptionsView { // THIS FAILS

}

class OptionsView extends PaginationView { // THIS WORKS

}

class BlahView extends OptionsView { // THIS WORKS

}

class PaginationView extends View { // THIS WORKS - EVEN IF VIEW IS IN ANOTHER SCRIPT AND DEFINED BEFORE THIS SCRIPT IS CALLED

}

Phil

ppowell

Actually I figured it out!

If I am correct, when PHP evaluates a script with classes it does class declaration from top-to-bottom parent-to-child, right?

let's say you have this:

class AlbumOptionsView extends PagOptionsView {

}

class PaginationView extends View {

}

class PagOptionsView extends PaginationView {

}

class ThumbView extends PaginationView {

}

This scenario works perfectly and I think I know why:

AlbumOptionsView can't yet be declared because PagOptionsView isn't declared yet
PaginationView can be declared because View has already been declared (in an earlier script)
PagOptionsView can be declared because PaginationView, its parent, has been declared
AlbumOptionsView can NOW be declared because its parent, PagOptionsView, has just now been declared
ThumbView can be declared because PaginationView, its parent, has been declared

Correct me if I am still way off but that's all I can think of.

Phil

rebelo

Seems reasonable to me.