PHP - How to share / pass variables across different methods in a PHP Class

Question

I am trying to set a value from a method of a class and trying to get it in another method. The example code is as below. I think the below kind of set/get works in a Java class. Googled out but still could not find a relevant solution.

Searched: http://www.google.co.in/search?hl=en&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial&q=how+to+share+data+across+functions+in+PHP&aq=f&aqi=&aql=&oq=&gs_rfai= http://stackoverflow.com/questions/2707442/pass-variable-number-of-variables-to-a-class-in-php http://stackoverflow.com/questions/1750837/php-call-member-variables-off-a-class-within-static-method

Thanks in advance.

<?php
class MyClass
{
    public $cons;

    function showConstant() {
        $this->setConstant(100); /* assign value to variable here */
        $this->showConstantGetter();
    }

    /* setter */
    function setConstant($aCons) {
        $cons  = $aCons;
    }

    /* getter */
    function getConstant() {
        return $cons;
    }


    function showConstantGetter() {
        echo "<br>getting const : ".$this->getConstant(); /* use the variable's value in this method here */
    }

}

$classname = "MyClass";
$class = new MyClass();
$class->showConstant();

?>

Answer 1

You must use $this->cons instead of $cons, that's all.

Answer 2

To access instance variables in PHP, you need to prefix them with $this->.

In your example:

    function getConstant() {
        return $this->cons;
    }

To access a class (or static) variable, you use self:: instead of $this->.

Answer 3

Nearly good but:

function setConstant($aCons) {
        $this->cons  = $aCons;
    }

    /* getter */
    function getConstant() {
        return $this->cons;
    }

Answer 4

Tried with $this-> operator as mentioned here. I get this error,

Fatal error: Cannot access empty property in C:\xampp\htdocs\varTest.php on line 13 in setter ie., $this->$cons = $aCons;

If I remove in line 13 it comes up with the same error in line 18 in getter ie., return $this->$cons;

Looks $this-> is having some problem. I use XAMPP version 1.7.2. Would there be any version issue?

Answer 5

Note that it is this:

$this->cons = $aCons;

and not this:

$this->$cons = $aCons;

If you specify $this->$cons, PHP will first look at the value in $cons and uses that as the name of the instance variable. In your case, there is nothing in $cons yet, so it will find a name that is empty, which causes the error message.

This type of indirection is not what you want to do here, so don't put the dollar sign in there twice!

Answer 6

This is what I tried. Still the value comes as blank. The earlier $this=>$cons is my mistake. Sorry.

/* setter */

function setConstant($aCons) { $this->cons = $aCons; }

/* getter */

function getConstant() { $this->cons; }

Answer 7

Hi Thanks for the answers. That was a very quick resolution. Appreciate it very much. Thanks everyone and all. Here is the complete code which works:

<?php
class MyClass
{
    var $cons;

    function showConstant() {
        $this->setConstant(100); /* assign value to variable here */
        $this->showConstantGetter();
    }

    /* setter */
    function setConstant($aCons) {
        $this->cons  = $aCons;
    }

    /* getter */
    function getConstant() {
        return $this->cons;
    }


    function showConstantGetter() {
        echo "<br>getting const : ".$this->getConstant(); /* use the variable's value in this method here */
    }

}

$classname = "MyClass";
$class = new MyClass();
$class->showConstant();

?>