Calling the parent constructor from a child class automatically.

I believe PHP calls its nearest constructor. if you need to call constructor from parent you can explicitly call it using parent::__const ructor();

So if the child (extending class) doesn't have any constructor then it calls parent constructor by default. Same goes for the case of grandparent constructor. See for example ::
[PHP]
<?
class top{
function __construct()

{

echo ("I'm In GrandParent");

}
}
class A extends top

{




}


class Child extends A

{

}

$test = new Child();

?>[/PHP]

now for your piece of code we can call the parent constructor using the following snippet of code ::
[PHP]
<?
class A

{

function __construct()

{

die("I'm In Parent");

}

}
class Child extends A

{

function __construct()

{

echo "going through child constructor..." ;
parent::__const ruct();
}

}

$test = new Child();

?>[/PHP]


hope this helps :)
cheers !!

I believe PHP calls its nearest constructor. if you need to call constructor from parent you can explicitly call it using parent::__const ructor();

So if the child (extending class) doesn't have any constructor then it calls parent constructor by default. Same goes for the case of grandparent constructor. See for example ::
[PHP]
<?
class top{
function __construct()

{

echo ("I'm In GrandParent");

}
}
class A extends top

{




}


class Child extends A

{

}

$test = new Child();

?>[/PHP]

now for your piece of code we can call the parent constructor using the following snippet of code ::
[PHP]
<?
class A

{

function __construct()

{

die("I'm In Parent");

}

}
class Child extends A

{

function __construct()

{

echo "going through child constructor..." ;
parent::__const ruct();
}

}

$test = new Child();

?>[/PHP]


hope this helps :)
cheers !!

Yeah thanks, I knew you could manually call it, but what's the point of having a constructor then. Defeats the purpose of automation.

I could place my task in a different function and call that instead.

I"m disappointed, this ruined my chance of a good framework I am building.

Thanks,

Dan

yup..
its doesn't call it automatically.. jus like it happens in java
may be there is some solution out ..

I don't get the problem.

Why would you want the parent constructor to be called automatically?
Even as it is not, would it not be just as effective to create a constructor that calls it's parent constructor?

I don't get the problem.

Why would you want the parent constructor to be called automatically?
Even as it is not, would it not be just as effective to create a constructor that calls it's parent constructor?

agreed.. cause that way you have a choice .. cause this gives you both options:

To call a parent constructor, if needed
Parent constructor do not gets called by default


But in case of java, i see no way u can ask proggie not to call Parent constructor if it exists in there.. Correct me if i am wrong ..

agreed.. cause that way you have a choice .. cause this gives you both options:

To call a parent constructor, if needed
Parent constructor do not gets called by default


But in case of java, i see no way u can ask proggie not to call Parent constructor if it exists in there.. Correct me if i am wrong ..

Okay you need a scenario, take mine.

I"m using my home-cooked MVC architecture and I keep building it.

Most of my pages have a few variables that I need to check for each single time. This is the "pageAction " variable. 99% of pages will have it.

I wanted to automatically get this pageAction from POST and put it in a var in the parent, that way the child controller does not have to do this everytime...hen ce automation.

If I have to call some constructor, or some function, I could just make it a rule and make sure each controller child class grabs the pageAction (They always have to if the page is not static)

For example here's a .php page that uses a customer controller (CT)
(I'm just typing this as i go and is not actual code)
[PHP]

//my includes
require_once("b lah.php"); //etc...

$customerCT = new CustomerCT();

switch($custome rCT->getPageAction( ))
{
case "Add":
$customerCT->add();
break;
case "Update":
$customerCT->update();
break;
}

$smrty->dispay("custom er.tpl");


[/PHP]

That's an over-simplified version of my architecture. In the constructor of CustomerCT I get POST variables that are specific to that page. "pageAction " is very common, exists on all pages with a submit button.

How do other frameworks do it (Cake, Zend, Symphony).

In the global include, or index.php file, they just grab it and put it in a global variable?

I guess that's one way.

So I could do

[PHP]

switch(PAGE_ACT ION)
{
case "Add" ....

[/PHP]

I guess that would work...yes? is it cleaner?

pbmods is good at ZendF, hopefully he can shed some light on this.

Thanks guys,

Dan

I would do it inside the Control object. Somewhat like:
Then I could call all pages somewhat like:
Is this not basically what you were trying to do?

I would do it inside the Control object. Somewhat like:

Expand|Select|Wrap|Line Numbers

1. class BaseCT {
2. protected $action;
3. public function __construct() {
4. $this->action = @$_GET['action'];
5. // And whatever other global CT constructor logic
6. }
7. }
8.  
9. class SomepageCT extends BaseCT {
10. public function __construct() {
11. parent::__construct();
12. // And whatever specialized constructor logic
13. }
14.  
15. public function execute() {
16. switch($this->$action) {
17. case "Add":
18. $this->_addSomething();
19. break;
20. case "Edit":
21. $this->_editSomething();
22. break;
23. default:
24. $this->_displaySomething();
25. break;
26. }
27. }
28.  
29. // Plus the private functions used by the execute method.
30. }
31.  

Then I could call all pages somewhat like:

Expand|Select|Wrap|Line Numbers

1. $className = (isset($_GET['page']) ? $_GET['page'] ."CT" : "DefaultCT");
2. $page = new $className();
3. $page->execute();
4.  

Is this not basically what you were trying to do?

Yeah you've got the right idea. Mine does the same thing as well if i call parent::__const ruct() inside each of my child's constructors.

I was trying to avoid that.

to force the call of a parent constructor you can use the 'final' keyword on the parents constructor.

of course, this means it can NEVER be overwritten, so use with caution.

[PHP]
class A {
final function __construct ($my,$args){
die("i've been called");
}
}
class B extends A{

}

$myobj = new B("hello", "world");

// i've been called
[/PHP]