Re: constructors are callable as regular functions.

troels knak-nielsen wrote: > On Thu, Jul 2, 2009 at 4:47 PM, Edward Z. Yang<ezyang@mit.edu> wrote: >> Excerpts from troels knak-nielsen's message of Thu Jul 02 10:14:18 -0400 2009: >>> I would have expected the second call to __construct() to yield an error. >> Why should it? Especially since this is idiomatic code: >> >> class A { >> public function __construct($a) { >> $this->a = $a; >> } >> } >> >> class B extends A { >> public function __construct($a, $b) { >> $this->b = $b; >> parent::__construct($a); >> } >> } > > In that example, the object instance is not initialised when > parent::__construct() is called. > >> __construct doesn't do anything like allocate memory. It just happens >> to get called when we do "new B(1, 2)" > > I understand that. It's not a technical issue - It's more a matter of > language semantics. Constructors are used for initializing state on an > object. Basically, this behaviour makes it impossible to implement > immutable objects in php. It's not a huge deal - I don't remember ever > seen __construct() called directly. > > -- > troels Hi, __construct can be private or protected, it just requires implementing a factory() or singleton() method to retrieve the immutable object. Greg