How Can I Dynamically Define Class Properties in PHP?

Dynamic Class Property Definition in PHP

In PHP, class properties are typically assigned static values during declaration. However, there are scenarios where it might be desirable to set property values dynamically using information available within the class itself.

Considering the following example:

class User {
    public $firstname = "jing";
    public $lastname  = "ping";
    public $balance   = 10;
    public $newCredit = 5;
}

Defining a property like $fullname = $this->firstname . ' ' . $this->lastname within the class raises a syntax error. This is because class properties must be initialized with constant values that can be evaluated at compile time.

To achieve dynamic property assignments, a suitable alternative is to use the class constructor. The constructor is invoked automatically when an object of the class is instantiated. By defining property assignments within the constructor, you can ensure that the values are initialized dynamically based on the state of the object:

class User {
    public $firstname;
    public $lastname;
    public $balance;
    public $newCredit;

    public function __construct() {
        $this->fullname  = $this->firstname . ' ' . $this->lastname;
        $this->totalBal  = $this->balance + $this->newCredit;
    }
}

As demonstrated in this revised code, the properties $fullname and $totalBal are dynamically assigned values within the constructor based on the values of other properties. This allows for flexible and customizable class property initialization using information available within the class instance.

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