Invoke function from initiated class within a class

[eros]

[PHP]
<?php
//clsrecordset.php
class Recordset extends Database{

public function Recordset( ) { }

public function query( ) { }

public function endOfFile ( ) { }

}
?>[/PHP]

[PHP]<?php
//clssearchindex.php
require_once('clsrecordset.php');

class Searchindex {
private c_rs;

public function Searchindex ( ) {
$this->c_rs = new Recordset( );
}

public function getSQL ( ) { }

public function getData ( ) {
$rs = $this->c_rs->query($this->getSQL()); // error occurred this line
$this->c_rs->query($this->getSQL());
if ( $this->c_rs->endOfFile() ) {
$norecs = true;
}
}
}
?>[/PHP]

Error message: Call to a member function query() on a non-object

Additional, when I type the $this->c_rs-> , there is no intellisense on this case that's why I know there is something wrong and couldn't find the function.

Help: How can I call the function from the initiated class in order to use in other class?

[Atli]

Are you sure you have called the method that initializes the c_rs object?

You should consider adding a constructor to initialize it, then there will be no risk of the variable not being initialized.

[eros]

Are you sure you have called the method that initializes the c_rs object?

You should consider adding a constructor to initialize it, then there will be no risk of the variable not being initialized.

[PHP]<?php
$pg = new Searchindex ( );
$pg->getData ( );
?>[/PHP]

Yes Sir, I use the new operator during initiation of the class then it is automatically invoke the Searchindex　constructor.

[Atli]

[PHP]<?php
$pg = new Searchindex ( );
$pg->getData ( );
?>[/PHP]

Yes Sir, I use the new operator during initiation of the class then it is automatically invoke the Searchindex　constructor.

Yea sorry, totally overlooked that. I've gotten to used to the __construct() syntax :)

The error is where you create the c_rs variable, you forgot the $ before the variable name.

[eros]

Yea sorry, totally overlooked that. I've gotten to used to the __construct() syntax :)

The error is where you create the c_rs variable, you forgot the $ before the variable name.

I think it is documented in php documentation when accessing the members itself, you only need the member name before $this-> .

For example:
[PHP]<?php
class MyClass {
private var1;
public var2;

public function MyClass ( ) {
// variable members initialization
$this->var1 = 1;
$this->var2 = "variable2";
// also calling function members
$this->MyFunction ( );

// "$" should be use when you need local variable.
// Therefore, $this->var? and $var? are treated differently.
$var1 = 2;
$var2 = "variable2";

$result = $this->var1 + $var1; // output 3
}

public function MyFunction ( ) { }
}
?>[/PHP]

[eros]

The above are the basics of PHP OOP, therefore it is not questionable unless I overlooked the code after my several times of investigations of what is really happening.

I created this topic because I feel strange of the error.. It must be correct syntactically and logically....

[eros]

I am very sorry guys I just missed looked / overlooked the code.

The code posted here was different in my source code.

[PHP]<?php
class Searchindex ( ) {
private $c_rs;

public function Searchindex ( ) {
/* this is the problem.
* It should be $this->c_rs = new Recordset ( );
*/
$c_rs = new Recordset ( );
}
}
?>[/PHP]

I make my own headache ;).. Thanks guys.

TOPIC CLOSED

[Atli]

Glad your code is working now.

Just to clear things up tho, take a look at this:

class myclass
{
  // This is incorrect, and will cause errors!
  private myVar;
 
  // This is correct
  private $myvar;
 
  function testFunc() {
    // This is correct, and will always refer to the variable
    // we declared before the function.
    echo $this->myvar;
 
    # EDIT, got this wrong the first time. It has been corrected.
    // This is not valid, it appears that the class variable
    // $myvar does not exist inside the scope of this function.
    // This will cause PHP to print a warning, if warnings are enabled.
    echo $myvar;
  }
}
 

[eros]

Glad your code is working now.

Just to clear things up tho, take a look at this:

class myclass
{
  // This is incorrect, and will cause errors!
  private myVar;
 
  // This is correct
  private $myvar;
 
  function testFunc() {
    // This is correct, and will always refer to the variable
    // we declared before the function.
    echo $this->myvar;
 
    // This is also correct, because the myvar variable
    // is declared inside the class, but any instances of
    // of $myvar inside the function will take over the scope.
    echo $myvar;
  }
}
 

Do you mean $this->myvar and $myvar are the same memory location? It means changes in $myvar are automatically reflected in $this->myvar and viceversa?

[Atli]

Do you mean $this->myvar and $myvar are the same memory location? It means changes in $myvar are automatically reflected in $this->myvar and viceversa?

No, it doesn't appear to work like that. I thought it did tho :/
Which means my earlier post was wrong. (I've edited it btw to show the error)

I made a simple test:

class myclass
{
    private $myvar;
 
    function myfunc()
    {
        $this->myvar = 5;
 
        echo $myvar; // = 'Undefined wariable' warning.
        echo $this->myvar; // = 5
 
        $myvar = 10;
 
        echo $myvar; // = 10
        echo $this->myvar; // = 5
    }    
}
 

So based on that, class variables can not be used inside class methods without $this.

It is possible, however, that this behavior may vary based on your configuration. This test was done using the default configuration.

[eros]

Yes that's it, Thank you very much.. It is highly appreciated.

TOPIC CLOSED

[pbmods]

Heya, Eros.

Class variables are DECLARED using '$' notation, but they are ACCESSED using '$this->'.

When you do this:

protected $myVar;
 

You are telling PHP to allocate memory for a protected variable named myVar.

The problem starts to manifest when you do something like this (which you should never do, but it is technically possible):

public function doSomething($myVar)
{
    echo $myVar;
}
 

What are we echoing here? The $myVar parameter to doSomething()? Or the protected member $myVar?

Hence, the $this notation:

public function doSomething($myVar)
{
    echo $this->myVar;
}
 

Since $this->myVar is the full reference to the variable, you only need to use one '$' sign.

Note that this would probably give you an error:

echo $this->$myVar;
 

because PHP would evaluate $myVar, and then attempt to echo $this->{value of $myVar}.

For more info, check out this document.