变量变量可以用于动态分配类属性，以便允许在PHP中使用变量参数的类构造函数吗？

Question

I am building a class and initially wanted to overload the constructs but discovered this is not allowed in PHP. My solution was using variable arguments for the one constructor. However, I am having some issues using string literals in a key => value pair and assigning the class properties. This leads me to ask my main question - is it actually possible to use variable variables to assign class properties via the constructor?

See example below:

class funrun{

   protected $run_id; 
   protected $fun_id; 
   protected $funrun_title; 
   protected $date; 

   function __construct(){

     if (func_num_args() > 0){
       $args = func_get_args(0); 
       foreach($args as $key => $value){
          $this->$key = $value;
       }

     $this->date = date();

     function __get($name){
        return $this->name; 
     }

     function __set($name,$value){
         $this->name = $value; 
     } 

}

This seems to correctly assign the values. But then when I do the following:

$settings = array ('run_id' => 5, 'fun_id' => 3); 
$fun_example = new funrun($settings); 
echo $fun_example->run_id; 

I get an error that the getter method isn't functioning:

Undefined property: funrun::$name

However, when I switch the class code to $this->key, the class property doesn't seem to be assigned at all. When I do $fun_example->$run_id, nothing is returned.

What am I missing here? Is there anyway to use an array with string literals to assign class properties? If not, what is a good way to tackle the variable argument issue with constructors?

Answer 1

$this->name is looking for a property named name. Variable properties are written as:

$this->$name

See the paragraph beginning with Class properties may also be accessed using variable property names. in the PHP documentation on variable variables

Your constructor is incorrectly written. It's iterating over the argument list, expecting it to be an associative array. But you're passing the settings as a single argument. So it should be:

function __construct($args) {
    foreach ($args as $key => $value) {
        $this->$key = $value;
    }
    $this->date = time();
}