Re: [PHP] Construction
As far as I know, this is fairly common in most programming languages (but I just woke up so don't take my word on it!). It allows you a lot greater control over the construction of your class, since you can force the child class to override what the parent class's default member variable values are by calling the parent constructor first, or you can have it be overridden by the parent by calling the parent constructor at the end of the child's constructor. Dave On Sat, 26 Jun 2004 20:51:58 -0700, Jason Davidson [EMAIL PROTECTED] wrote: If you instantiate a child class, the parent class constructor is not called, is there a reason for this? anyone know of plans to change this at all, the obvious workaround is to call the parents constructor inside the childs constructor, but this seems kinda strange. Jason -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Construction
On Sat, 26 Jun 2004 20:51:58 -0700, Jason Davidson
[EMAIL PROTECTED] wrote:
If you instantiate a child class, the parent class constructor is not
called, is there a reason for this? anyone know of plans to change
this at all,
the obvious workaround is to call the parents constructor inside the
childs constructor, but this seems kinda strange.
I think it's unlikely to change. PHP5 also works this way, though it
uses constructor methods named __construct (in addition to allowing
old-style constructors with the name of the class).
?php
// PHP5
class Foo
{
function __construct()
{
$this-x = data;
}
}
class Bar extends Foo
{
function __construct()
{
parent::__construct();
$this-y = more data;
}
}
?
FWIW Python also requires child classes to call parent constructors
manually. Not sure what the justification is for this design decision
is, though, in either language. Anybody?
pb
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RE: [PHP] Construction
Paul Bissex wrote: FWIW Python also requires child classes to call parent constructors manually. Not sure what the justification is for this design decision is, though, in either language. Anybody? Flexibility, I would guess. With PHP's current behavior one can: (1) Call the parent constructor first, before the subclass constructor does its work. (2) Call the parent constructor last, after the subclass constructor does its work. (3) Call the parent constructor in the middle...doing some work before, and then some work after. :) (3) Pass through all of the subclass constructor's arguments to the parent constructor unaltered. (4) Change or filter some of the arguments that get passed to the parent constuctor. (5) Choose not to call the parent constructor at all. (6) Many other things that I'm sure I'm overlooking... If PHP called the parent constructor for you automagically, then how would you implement the above options? PHP would have to choose one approach and stick to it. I like the current behavior much better. Forgive me if this has been mentioned in this thread previously, but PHP does call the parent class constructor automatically if the subclass has no constuctor, which does make sense -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
[PHP] Construction
If you instantiate a child class, the parent class constructor is not called, is there a reason for this? anyone know of plans to change this at all, the obvious workaround is to call the parents constructor inside the childs constructor, but this seems kinda strange. Jason -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
