Parent Objects

[paul.j]

I have

class thechild{
function sayTest()
{
parent::test(); // this right???
}
}

class theparent{
function test()
{
echo "test";
}
function __construct()
{
$e = new thechild();
$e->sayTest();
}
}

How do i get this to work ? I am trying to get a one class (A) to
create another class (B) within it, but the class B must be able to
call a function from class A. Any ideas?

Thanks
Paul Jenkins

https://www.pjenkins.co.uk

[Jerry Stuckle]

Re: Parent Objects

paul.j wrote:

I have
>
class thechild{
function sayTest()
{
parent::test(); // this right???
}
}
>
class theparent{
function test()
{
echo "test";
}
function __construct()
{
$e = new thechild();
$e->sayTest();
}
}
>
How do i get this to work ? I am trying to get a one class (A) to
create another class (B) within it, but the class B must be able to
call a function from class A. Any ideas?
>
Thanks
Paul Jenkins

https://www.pjenkins.co.uk

>

No, this is not correct. You have no parent-child relationship between
them; theparent's constructor just creates a thechild object (then
throws it away when the constructor exits.

And think about this - what happens if you just had:

function myfunc() {
$c = new thechild();
...
}

IOW, you're creating a new thechild object outside of a theparent
object. What would the statement "parent::text() " do then?

Look at the "extends" keyword. Use it to derive thechild from theparent.


--
=============== ===
Remove the "x" from my email address
Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attgl obal.net
=============== ===

[Sanders Kaufman]

Re: Parent Objects

Jerry Stuckle wrote:

IOW, you're creating a new thechild object outside of a theparent
object. What would the statement "parent::text() " do then?

What does "::" mean?
Is that a shortcut for "->"?

[Heiko Richler]

Re: Parent Objects

Sanders Kaufman wrote:

What does "::" mean?
Is that a shortcut for "->"?

No, it is the Scope Resolution Operator

http://www.php.net/manual/en/language.oop5.paamayim-nekudotayim.php

Heiko
--
http://portal.richler.de/ Namensportal zu Richler
http://www.richler.de/ Heiko Richler: Computer - Know How!
http://www.richler.info/ private Homepage

[Sanders Kaufman]

Re: Parent Objects

Heiko Richler wrote:

Sanders Kaufman wrote:

>What does "::" mean?
>Is that a shortcut for "->"?

>
No, it is the Scope Resolution Operator

http://www.php.net/manual/en/language.oop5.paamayim-nekudotayim.php

>
Heiko

I read that, but I'm still a little confused.
When I use a class's methods and such, I've been using "->".
But it seems like this "::" is used the same way.
What's the difference?

[Rik]

Re: Parent Objects

Sanders Kaufman wrote:

Heiko Richler wrote:

>Sanders Kaufman wrote:

>>What does "::" mean?
>>Is that a shortcut for "->"?

>>
>No, it is the Scope Resolution Operator
>http://www.php.net/manual/en/languag...ekudotayim.php
>>
>Heiko

>
I read that, but I'm still a little confused.
When I use a class's methods and such, I've been using "->".
But it seems like this "::" is used the same way.
What's the difference?

Simplified: it's the difference between objects and classes.
--
Rik Wasmus

[Rik]

Re: Parent Objects

paul.j wrote:

I have
>
class thechild{
function sayTest()
{
parent::test(); // this right???
}
}
>
class theparent{
function test()
{
echo "test";
}
function __construct()
{
$e = new thechild();
$e->sayTest();
}
}
>
How do i get this to work ? I am trying to get a one class (A) to
create another class (B) within it, but the class B must be able to
call a function from class A. Any ideas?

You could make named class variables. It's up to yourself they work though:

class thechild{
var $parent;
function __construct(&$o bject){
$this->parent =& $object;
}
function sayTest()
{
$this->parent->test();
}
}
class theparent{
var $child;
function test()
{
echo "test";
}
function __construct()
{
$this->child = new thechild($this) ;
$this->child->sayTest();
}
}
--
Rik Wasmus

[Sanders Kaufman]

Re: Parent Objects

Rik wrote:

Sanders Kaufman wrote:

>>>What does "::" mean?
>>>Is that a shortcut for "->"?

>>No, it is the Scope Resolution Operator
>>http://www.php.net/manual/en/languag...ekudotayim.php

>I read that, but I'm still a little confused.
>When I use a class's methods and such, I've been using "->".
>But it seems like this "::" is used the same way.
>What's the difference?

>
Simplified: it's the difference between objects and classes.

Two part question here:

[1]
OK - but on a more practical level, what's the difference.
I mean -like, in my code I'll create a class.
In that class, I'll reference it's members with "$this->member".
Then, somewhere else I'll create an object based on the class
and reference it's members with "$class->member".

Where would I use "::"?

[2]
Perhaps I would understand better if I understood what is meant
by the phrase "scope resolution operator".
So why is it called that?
Maybe more specifically, what does "resolution " mean in this
context?

[Rik]

Re: Parent Objects

Sanders Kaufman wrote:

Rik wrote:

>Sanders Kaufman wrote:

>

>>>>What does "::" mean?
>>>>Is that a shortcut for "->"?

>

>>>No, it is the Scope Resolution Operator
>>>http://www.php.net/manual/en/languag...ekudotayim.php

>

>>I read that, but I'm still a little confused.
>>When I use a class's methods and such, I've been using "->".
>>But it seems like this "::" is used the same way.
>>What's the difference?

>>
>Simplified: it's the difference between objects and classes.

>
Two part question here:
>
[1]
OK - but on a more practical level, what's the difference.
I mean -like, in my code I'll create a class.
In that class, I'll reference it's members with "$this->member".
Then, somewhere else I'll create an object based on the class
and reference it's members with "$class->member".
>
Where would I use "::"?

You wouldn't, as it are all objects, and not classes. You'd only need it if
your class extended another class and you wished to call a parents method.

http://www.php.net/manual/en/language.oop5.paamayim-nekudotayim.php

--
Rik Wasmus

[Michael Fesser]

Re: Parent Objects

..oO(Sanders Kaufman)

>I read that, but I'm still a little confused.
>When I use a class's methods and such, I've been using "->".
>But it seems like this "::" is used the same way.
>What's the difference?

$someObject->method()
someClass::stat icMethod()

'->' requires an instance of a class, whereas '::' is used to call
static class methods or constants without having an object. Additionally
it's used to call inherited methods.

Micha

[Toby Inkster]

Re: Parent Objects

Sanders Kaufman wrote:

When I use a class's methods and such, I've been using "->".
But it seems like this "::" is used the same way.

Using '::' you can call a classes methods, constants and static functions
(here's the key part) without instantiating an object of that class.

Example:

<?php
include "Widget.class.p hp";
echo Widget::FOO;
?>

Versus:

<?php
include "Widget.class.p hp";
$my_widget = new Widget();
echo $my_widget->FOO;
?>

Another example:

<?php
class Widget
{
function exist ()
{
return isset($this);
}
}
$my_widget = new Widget();
$my_widget->exist(); // true
Widget::exist() ; // false
?>

That is, '->' forces a function to run on a specific object, whereas '::'
runs the function without the object instance (i.e. '$this' is undefined).

--
Toby A Inkster BSc (Hons) ARCS
Contact Me ~ http://tobyinkster.co.uk/contact

[Sanders Kaufman]

Re: Parent Objects

Rik wrote:

Sanders Kaufman wrote:

>Where would I use "::"?

>
You wouldn't, as it are all objects, and not classes. You'd only need it if
your class extended another class and you wished to call a parents method.
>
http://www.php.net/manual/en/languag...ekudotayim.php

OH! So if my class has a method, and then another class extends
the class and overrides(?) the method, I can call the original
method with "::"?

[Sanders Kaufman]

Re: Parent Objects

Michael Fesser wrote:

.oO(Sanders Kaufman)
>

>I read that, but I'm still a little confused.
>When I use a class's methods and such, I've been using "->".
>But it seems like this "::" is used the same way.
>What's the difference?

>
$someObject->method()
someClass::stat icMethod()
>
'->' requires an instance of a class, whereas '::' is used to call
static class methods or constants without having an object. Additionally
it's used to call inherited methods.

D'oh!
I thought I had it - but then you said something about static stuff.
And I think I'm futzed up about Object v. Class here.

So let's see if I've got it better this way:

I call my OBJECT methods with "->".
I call my CLASS methods with "::".

Ja?

[Sanders Kaufman]

Re: Parent Objects

Toby Inkster wrote:

<?php
include "Widget.class.p hp";
echo Widget::FOO;
?>
>
Versus:
>
<?php
include "Widget.class.p hp";
$my_widget = new Widget();
echo $my_widget->FOO;
?>

It means that I can call the CLASS method, without
instantiating(? ) an object, right?

Man, oh man, that could be real handy for my classes that don't
do too much stuff in the constructor!

Wait... I guess I shouldn't assume here. So I'll ask - when I
call a class method with "::", it won't fire up the constructor,
will it?

[Michael Fesser]

Re: Parent Objects

..oO(Sanders Kaufman)

>D'oh!
>I thought I had it - but then you said something about static stuff.

A static class method can be called without having to create an object
first.

>And I think I'm futzed up about Object v. Class here.

An object is an incarnation of a class, which itself is more or less
just a "blueprint" for creating objects.

>So let's see if I've got it better this way:
>
>I call my OBJECT methods with "->".
>I call my CLASS methods with "::".

Yep, that's one of its uses.

Micha