Re: [PHP] accessing variables within objects
- From: lists@xxxxxxxxx (Jim Lucas)
- Date: Thu, 31 Jul 2008 11:49:24 -0700
Philip Thompson wrote:
On Jul 30, 2008, at 1:29 PM, Jim Lucas wrote:
Marten Lehmann wrote:Hello,
I'm using some php-classes which worked fine with php-5.0.4. Now I tried to upgrade to php-5.2.6, but the classes give a lot of errors. If I set
error_reporting(E_ALL);
I see messages like
Notice: Undefined property: FastTemplate::$main in /whereever/inc.template.php on line 293
Notice: Undefined property: current_session::$cust_id in /whereever/inc.init.php on line 117
In inc.template.php there are a lot of calls like $this->$key. In inc.init.php there are calls like $session->cust_id.
to fix these errors, you would need to modify the code so it does something like this.
where it calls $this->$key you need to check and make sure that $key exists before you trying call for it.
So something like this would work.
if ( isset( $this->$key ) ) {
$this->$key;
} else {
$this->$key = null;
}
You didn't show any context in which you are using the above code. So I don't know what will actually work in your situation. Show a little more code that includes the method in which $this->$key is called.
You will want to look at using the Overloading feature of PHP5. Check out this page for overloading examples
http://us2.php.net/manual/en/language.oop5.overloading.php
Take note of the __get() and __set() methods. The __get method checks to see if the key exists before it tries working with it.
Ok, I'm trying to understand the point to using these overloading methods.
<?php
$obj = new ClassThatUsesOverloading ();
$obj->hi = 'Hi';
$obj->bye = 'Bye';
echo $obj->hi, ' ', $obj->bye;
// Output: Hi Bye
?>
I was only suggesting the overloading because it would be the simplest thing to implement in an existing class without massively re-write parts of your application.
You could simply add the __get() method and then have it check to see if the value or $key existed before it tries using it. And if it doesn't exist, then return null or something else. This would get rid of a lot of your NOTICEs from PHP.
I would add a method something like the following to your class and it should fix the problems with trying to access properties that do not exist.
function __get($key) {
// Check for the existence of the key in object
if ( isset( $this->$key ) {
// If found, return value
return $this->$key;
}
// Default: return null
return null;
}
You could have done that or you could do the following.....
<?php
$obj = new ClassThatDoesntUseOverloading ();
$obj->setHi('Hello');
$obj->setBye('Bye Bye!');
echo $obj->hi(), ' ', $obj->bye();
// Output: Hello Bye Bye!
?>
This example is flawed by the fact that you are call hi and bye as a method instead of referencing the property.
The 2nd way seems more *OOP* than the first - weird to explain. I guess what I'm wanting to know is.... why would you use overloading (in PHP)? The only reason I can think of is to avoid having to create/use accessors. Please help me understand! But please be nice! =D
Thanks,
~Philip
What has changed in php-5.2.x so that these calls don't work any more? What is the new, required form to use objects in a similar manner (unfortunately I have no ressources to code these classes from scratch)? Thanks.
Kind regards
Marten
--
Jim Lucas
"Some men are born to greatness, some achieve greatness,
and some have greatness thrust upon them."
Twelfth Night, Act II, Scene V
by William Shakespeare
.
- References:
- accessing variables within objects
- From: Marten Lehmann
- Re: [PHP] accessing variables within objects
- From: Jim Lucas
- Re: [PHP] accessing variables within objects
- From: Philip Thompson
- accessing variables within objects
- Prev by Date: Re: [PHP] accessing variables within objects
- Next by Date: Re: [PHP] Dynamic Select Lists - 1st Selection Effects 2nd!
- Previous by thread: Re: [PHP] accessing variables within objects
- Next by thread: Re: [PHP] accessing variables within objects
- Index(es):
Relevant Pages
|
