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+--- Thread: Scope of $data problems (/showthread.php?tid=52703)
Scope of $data problems - El Forum - 06-22-2012
[eluser]A_funs[/eluser]
I am trying to access data passed into $data in the constructor in other methods, $data is public so why isn't this working
<?php
class Company extends CI_Controller{
public $data;
function __construct(){
parent::__construct();
$data['something'] = 'something';
}
function submit_addcompany(){
$data['test_2'] = "something else";
//HOPEFULLY $data will contain both 'something and 'something else';
}
}
}
Scope of $data problems - El Forum - 06-22-2012
[eluser]PhilTem[/eluser]
There's a difference in
Code:
$data
// and
$this->datawhich you seem to not be totally clear about.
If you want to pass data between methods you either pass them as arguments or as class-attributes.
Scope of $data problems - El Forum - 06-22-2012
[eluser]A_funs[/eluser]
Thanks,
So can you explain the difference a bit, after reading your response I tried this and got some errors...
<?php
class test extends CI_Controller{
function __construct(){
$data->name = "Alex";
}
function index(){
echo $data->name;
}
}
Scope of $data problems - El Forum - 06-22-2012
[eluser]A_funs[/eluser]
sorry that last didn't make sense, this is still giving errors too...
<?php
class test extends CI_Controller{
function __construct(){
$data['name'] = "Alex";
}
function index(){
echo $this->$data['name'];
}
}
Scope of $data problems - El Forum - 06-22-2012
[eluser]A_funs[/eluser]
OK got it... it was the dollar sign..
Thanks for your help
Scope of $data problems - El Forum - 06-22-2012
[eluser]CroNiX[/eluser]
For more info on how to do OOP in php, try checking out the manual. http://php.net/manual/en/language.oop5.php. If you don't understand OOP, you will have a harder time with CI. These are concepts you should really know before using CI to get the most of it.
Scope of $data problems - El Forum - 06-22-2012
[eluser]A_funs[/eluser]
Thanks CroNIX,
I am getting pretty close to having what I believe to be an adequate understanding of OO principles, This one distinction between properties and variables seems to be escaping me though.
If within my object I declare a public variable like "public $testdata" am I not making that variable available to all methods?
Or is what I am really doing declaring a public property, which if I want to use across methods, I need to refer to as such with $this->testdata?
thanks again
Scope of $data problems - El Forum - 06-22-2012
[eluser]CroNiX[/eluser]
Class variables, aka properties, are accessible only when using $this, as $this refers to the entire object, not the individual method. So you need to use $this to access individual class properties throughout the class.
Code:
class Someclass extends CI_Controller {
public $data; //class property declaration, only accessible by using $this->data
public __construct()
{
parent::__construct();
$this->data = 'my property data'; // populate property on construct
echo $this->data; // 'my property data'
}
function some_function()
{
$data = 'test'; //this is a local variable only available to this method, some_function().
$this->data = 'other data'; //this is setting the class property, $data
echo $data; // "test"
echo $this->data // "other data"
}
function another_function()
{
echo $this->data; // 'my property data'
echo $data; //this is undefined in this method as it is defined in some_function
}
}In the above, when the class is instantiated, it sets the property, $data and echos it.
'my property data'
If you go to /someclass/some_function:
-goes through constructor first, sets property $data and echos it
-sets local variable $data, sets property $data and echoes them both
'my property data'
'test'
'other data'
If you go to /someclass/another_function
-goes through constructor first, sets property $data and echos it
-echos property $data, again
-produces error that variable $data is undefined as it's only available within some_function where it was declared as a local variable.
'my property data'
'my property data'
error, $data is undefined
Hope that helps a bit. There is a difference between class variables and local variables, and you have to access them as such.