PHP Classes Troubles

[d_barszczak]

Hi,

Ok basically i have 2 classes on 2 seperate php files one controls the database functions for my app and the other controls the session management so that a list of current online users can be displayed.

The problem im having is that the sessions class needs to use some functions from the database class but all i get is this error code.


[i]Fatal error: Call to a member function connect() on a non-object in D:\www\LocalUser\callmanager\classes\sessions.conf.php on line 12[/i]

Example code would be as follows.

[code]
<?php

class sessions {
     
function check() {
$sesid = session_id();
$query = "SELECT * FROM sessions WHERE id = '$sesid'";

$mysqldb->connect();
}

}
[/code]

You can call $mysqldb->connect(); from anywhere except from withing the class tags.

[d_barszczak]

Its ok sorted it now!

[448191]

Argh. You already posted you sorted it out while I was writing this, but I'll post it anyway.

You need to read up on 'variable scope'.

For now, to fix this, you have 2+ options:

1) have session EXTEND mysqldb:
[code]<?php
class session extends mysqldb {
?>[/code]
All public methods and properties of mysqldb will come available to session:
[code]<?php
parent::connect();
?>[/code]
or
[code]<?php
$this->connect();
?>[/code]

2) Have a property of session contain an instantiation of mysqldb:
[code]<?php
class session {
private mysqldb;

function __construct()
{
 $this->mysqldb = new mysqldb();

}
?>[/code]

Latter option example only works with php 5, but same can be accomplished with php4.

[d_barszczak]

Not the way i did it but your ways better so thankyou for your comments.

[trq]

I wouldn't recomend making the [i]session[/i] class an extension of the [i]mysql[/i] class... they have nothing to do with each other. Thats just plain bad OOP.

The later approuch is a more appropriate solution.

[448191]

[quote author=thorpe link=topic=101896.msg403854#msg403854 date=1153922888]
I wouldn't recomend making the [i]session[/i] class an extension of the [i]mysql[/i] class... they have nothing to do with each other. Thats just plain bad OOP.

The later approuch is a more appropriate solution.
[/quote]

Just out of curiousity; when would you extend one class with another? If need practicly all of the parents methods, how can a claim they aren't related hold any ground?

I'm asking because I've got a LOT of classes that need each others methods and props. Some of them are in this long chain of extends, some are referered to by object references. I have it depend on wether you need the parent class in the child class on most logicpaths...

Some thoughts one this are more than welcome!  :)