PHP：在构造函数中使用$ this

Question

I have an idea of using this syntax in php. It illustrates that there are different fallback ways to create an object

function __construct() {

   if(some_case())
      $this = method1();
   else
      $this = method2();

}

Is this a nightmare? Or it works?

Answer 1

Or it works?

It doesn't work. You can't unset or fundamentally alter the object that is being created in the constructor. You can also not set a return value. All you can do is set the object's properties.

One way to get around this is having a separate "factory" class or function, that checks the condition and returns a new instance of the correct object like so:

function factory() {

   if(some_case())
      return new class1();
  else
      return new class2();

}

See also:

• Breaking the constructor
• PHP constructor to return a NULL