[RESOLVED] Creating object/class properties dynamically at run time

[OOP]

Hi there,
I am just about the correct way of creating object properties/attribute dynamically at run time. I am doing it using the magic methods set() and get(). However, while reading some others code, I have noticed that they are using another way to do the same.

to illustrate other's way, let us say that I have a very basic class as shown below:

class Foo{
      public $var1;
      public $var2;

  function assign_value($key,$value){
          $this->$key = $value;
  }
}

$foo = new Foo();
$foo->assign_value('var1','test1');  // This is okay becuase var one is already defined in the class
$foo->assign_value('var2','test2');  // This is the same as the first one
$foo->assign_value('var3','test3');   // doing this will create a new attributes called var3 and you can refere to it using $this->var3;

Now, how come var3 was created at run time without using the magic method __set()? Was it called implicitly by the PHP engine to create var3 at run time?

your usual help is appreciated

[NogDog]

A class's method can always create an object variable at runtime if it does not exist, so when you call your assign_value() method, it creates the object variable if if does not already exist. I believe __set() will do the same thing: all that is different about it is that it gets called any time you try to set an object variable that is not a public variable, which can be either a class-defined private/protected variable or an undefined variable.

However, you can prevent this side effect by adding some logic to your setter methods to see if the variable exists before creating/setting it.

<?php
class Foo
{
   private $var1;
   public function __set($name, $value)
   {
      $this->$name = $value;
   }
}

class Bar
{
   private $var1;
   public function __set($name, $value)
   {
      if(property_exists($this, $name)) {
         $this->$name = $value;
         return true;
      }
      else {
         throw new Exception ("Invalid varname '$name'");
      }
   }
}

try {
   $foo = new Foo();
   $foo->var1 = 'one';
   $foo->var2 = 'two';
   echo "<pre>".print_r($foo,1)."</pre>\n";
   $bar = new Bar();
   $bar->var1 = 'one';
   $bar->var2 = 'two'; // should throw exception
}
catch(Exception $e) {
   echo "<pre>" . (string) $e . "</pre>";
}

Output:

Foo Object
(
    [var1:private] => one
    [var2] => two
)

exception 'Exception' with message 'Invalid varname 'var2'' in C:\wamp\www\test\test.php:21
Stack trace:
#0 C:\wamp\www\test\test.php(33): Bar->__set('var2', 'two')
#1 {main}

[OOP]

Thanks so much for the clarification