Calling a subclass's method

**Rik** · Jun 14 '06, 08:15 AM

Re: Calling a subclass's method

Ramon wrote:[color=blue]
> Hello
>
> I'm new to OOP in PHP and I have this question:
>
> I have a class called "Form", which contains a collection of classes
> (objects) called "Textbox".
> Now I need to call the Textbox class's method "getOuterHTML() ".
>
> In Visual Basic, you should do it like this:
> oForm.getTextBo xByID("Number") .getOuterHTML()
>
> In PHP I tried this: $oForm->getTextBoxByID ("Number")->getOuterHTML() ;
> But that doesn't work...
>
> Is there a way to do this in one statement? (I use PHP4).[/color]

How does you object "contain" the textboxes, and how have you defined the
method getTextBoxByID?

I'm no real OOP programmer, but in this case I'd:

<?php

class B{
function display(){
echo "works";
}
}

class A{
var $bs = array();
function add(){
$this->bs[] = new B;
}
}

$a = new A;
$a->add();

$a->bs[0]->display();

?>

Grtz,
--
Rik Wasmus

**dbunny** · Jun 14 '06, 08:16 AM

PHP 4 or 5? 5 supports a syntax similar to what you have above, but I'd need more info. I know that PHP5 doesn't allow calling a subclass method if it's not declared explicitly in th e parent class (usually as abstract, or public...) But that's probably not what you're problem is. PHP4 doesn't allow "linking" together objects like you're doing (but 5 does), and so:

$box = $oForm->getTextBoxByID ("Number");
$contents = $box->getOuterHTML() ;

Does this work?

(Oh - re-read you have PHP 4. Nope, gotta use two statements or upgrade to PHP5)

**Tony Marston** · Jun 14 '06, 08:25 AM

Re: Calling a subclass's method

What you are describing is not a subclass but a contained object. A subclass
inherits from a superclass whereas you are instantiating an object from
within another object. There is a difference.

What you want is this...

$oForm->getTextBoxBy ID->getOuterHTML(" Number");

--
Tony Marston

Tony Marston's Web Site

http://www.tonymarston.net

This is Tony Marston's web site, containing personal information plus pages devoted to the Uniface 4GL development language, XML and XSL, PHP and MySQL, and a bit of COBOL

Rapid Application Development Toolkit | RAD Web App Framework

http://www.radicore.org

Build apps faster with Rapid Application Development using open-source RAD tools, modern RAD frameworks, and rapid application design methods.

"Ramon" <itsramon@zonne t.nl> wrote in message
news:448fc280$0 $31637$e4fe514c @news.xs4all.nl ...[color=blue]
> Hello
>
> I'm new to OOP in PHP and I have this question:
>
> I have a class called "Form", which contains a collection of classes
> (objects) called "Textbox".
> Now I need to call the Textbox class's method "getOuterHTML() ".
>
> In Visual Basic, you should do it like this:
> oForm.getTextBo xByID("Number") .getOuterHTML()
>
> In PHP I tried this: $oForm->getTextBoxByID ("Number")->getOuterHTML() ;
> But that doesn't work...
>
> Is there a way to do this in one statement? (I use PHP4).
>
>
> Thanks in advance!
> Ramon.
>[/color]

**Ramon** · Jun 14 '06, 08:55 AM

Re: Calling a subclass's method

Thanks Tony for your explanation,

but I don't think I understand your solution. The getOuterHTML method
expects no parameters. This is the error I get: "Call to a member function
on a non-object". Did you mean that I have to adjust the getOuterHTML method
in any way?

This is my code (in short):

<?

class TextBox {
var $m_sID;
var $m_sName;
var $m_sValue;

// Class Constructor:
function TextBox ($sID, $sName, $sValue) {
$this->m_sID = $sID;
$this->m_sName = $sName;
$this->m_sValue = $sValue;
}

function getID() {
return $this->m_sID;
}

function getOuterHTML () {
return "<input type='text' name='" . $this->m_sName . "' value=' .
$this->m_sValue . '>";
{

}

class HTMLForm {
var $m_oTextBoxes = array();

function addTextBox($oTe xtBox) {
$this->m_oTextBoxes[$oTextBox->getID()] = $oTextBox;
}

function getTextBoxByID ($sID) {
return ($this->m_oTextBoxes[$sID]);
}
}

$oTxtNumber = new TextBox ("Nr", "Number", "123");
$oForm->addTextBox ($oTxtNumber);

echo $oForm->getTextBoxByID ("Nr")->getOuterHTML() ;

?>

"Tony Marston" <tony@NOSPAM.de mon.co.uk> wrote in message
news:e6ogua$pti $1$8302bc10@new s.demon.co.uk.. .[color=blue]
> What you are describing is not a subclass but a contained object. A
> subclass inherits from a superclass whereas you are instantiating an
> object from within another object. There is a difference.
>
> What you want is this...
>
> $oForm->getTextBoxBy ID->getOuterHTML(" Number");
>
> --
> Tony Marston
> http://www.tonymarston.net
> http://www.radicore.org
>
>
> "Ramon" <itsramon@zonne t.nl> wrote in message
> news:448fc280$0 $31637$e4fe514c @news.xs4all.nl ...[color=green]
>> Hello
>>
>> I'm new to OOP in PHP and I have this question:
>>
>> I have a class called "Form", which contains a collection of classes
>> (objects) called "Textbox".
>> Now I need to call the Textbox class's method "getOuterHTML() ".
>>
>> In Visual Basic, you should do it like this:
>> oForm.getTextBo xByID("Number") .getOuterHTML()
>>
>> In PHP I tried this: $oForm->getTextBoxByID ("Number")->getOuterHTML() ;
>> But that doesn't work...
>>
>> Is there a way to do this in one statement? (I use PHP4).
>>
>>
>> Thanks in advance!
>> Ramon.
>>[/color]
>
>[/color]

**Rik** · Jun 14 '06, 09:25 AM

Re: Calling a subclass's method

Ramon wrote:[color=blue]
> This is my code (in short):[/color]
[color=blue]
> function getOuterHTML () {
> return "<input type='text' name='" . $this->m_sName . "'
> value=' . $this->m_sValue . '>";
> {[/color]

I assume the { is } in your actual code?

Try this:

<?
class TextBox {
var $m_sID;
var $m_sName;
var $m_sValue;

// Class Constructor:
function TextBox ($sID, $sName, $sValue) {
$this->m_sID = $sID;
$this->m_sName = $sName;
$this->m_sValue = $sValue;
}

function getID() {
return $this->m_sID;
}

function getOuterHTML(){
return "<input type='text' name='$this->m_sName'
value='$this->m_sValue'>";
}

}

class HTMLForm {
var $m_oTextBoxes = array();

function addTextBox($oTe xtBox) {
$this->m_oTextBoxes[$oTextBox->getID()] = $oTextBox;
}
}

$oTxtNumber = new TextBox ("Nr", "Number", "123");
$oForm = new HTMLForm;
$oForm->addTextBox($oT xtNumber);
echo $oForm->m_oTextBoxes["Nr"]->getOuterHTML() ;
?>

Works fine in PHP4 here.

Grtz,
--
Rik Wasmus

**Ramon** · Jun 14 '06, 09:45 AM

Re: Calling a subclass's method

Thanks Rik,

this does work.
I'm sorry that I keep asking, but I'm trying to understand this.

I wonder if this is the correct way to address the $m_oTextBoxes array.
That array should be treated as if it were private, I suppose..?

Actually, I should have an interface method to call this array:

class HTMLForm {
var $m_oTextBoxes = array();

// Added method: =============== =============== ==========

function getTextBoxByID( $sID) {
return This->m_oTextBoxes[$sID];
}

// =============== =============== =============== =========

function addTextBox($oTe xtBox) {
$this->m_oTextBoxes[$oTextBox->getID()] = $oTextBox;
}

}

Then, I still have the question how to call the right instance of the
TextBox-class's getOuterHTML method.

Because this will not work here: echo
$oForm->m_oTextBoxes["Nr"]->getOuterHTML() ;

Thanks for your patience!
Ramon.

?>

"Rik" <luiheidsgoeroe @hotmail.com> wrote in message
news:581f9$448f d547$8259c69c$1 4103@news1.tude lft.nl...[color=blue]
> Ramon wrote:[color=green]
>> This is my code (in short):[/color]
>[color=green]
>> function getOuterHTML () {
>> return "<input type='text' name='" . $this->m_sName . "'
>> value=' . $this->m_sValue . '>";
>> {[/color]
>
>
> I assume the { is } in your actual code?
>
> Try this:
>
> <?
> class TextBox {
> var $m_sID;
> var $m_sName;
> var $m_sValue;
>
> // Class Constructor:
> function TextBox ($sID, $sName, $sValue) {
> $this->m_sID = $sID;
> $this->m_sName = $sName;
> $this->m_sValue = $sValue;
> }
>
> function getID() {
> return $this->m_sID;
> }
>
> function getOuterHTML(){
> return "<input type='text' name='$this->m_sName'
> value='$this->m_sValue'>";
> }
>
> }
>
> class HTMLForm {
> var $m_oTextBoxes = array();
>
> function addTextBox($oTe xtBox) {
> $this->m_oTextBoxes[$oTextBox->getID()] = $oTextBox;
> }
> }
>
> $oTxtNumber = new TextBox ("Nr", "Number", "123");
> $oForm = new HTMLForm;
> $oForm->addTextBox($oT xtNumber);
> echo $oForm->m_oTextBoxes["Nr"]->getOuterHTML() ;
> ?>
>
> Works fine in PHP4 here.
>
> Grtz,
> --
> Rik Wasmus
>
>[/color]

**Rik** · Jun 14 '06, 09:55 AM

Re: Calling a subclass's method

Ramon wrote:[color=blue]
> Thanks Rik,
>
> this does work.
> I'm sorry that I keep asking, but I'm trying to understand this.
>
> I wonder if this is the correct way to address the $m_oTextBoxes
> array. That array should be treated as if it were private, I
> suppose..?[/color]

In PHP4, it cannot be made private.
An array in an object is just like any other array, so it's the correct way
of adressing it.

[color=blue]
> Actually, I should have an interface method to call this array:[/color]

I've been trying some things, it seems it cannot be done in one line, except
when using constructs like:
call_user_func( array($oForm->getgetTextBoxB yID("Nr"), 'outerHTML));

But I'm no real OOP programmer, maybe someone else could enlighten you.
[color=blue]
> Then, I still have the question how to call the right instance of the
> TextBox-class's getOuterHTML method.
>
> Because this will not work here: echo
> $oForm->m_oTextBoxes["Nr"]->getOuterHTML() ;[/color]

First it does work, now it doesn't work? Works perfectly here.

If it actually doesn't work, try turning on error_reporting and var_dump()
your objects. (For instance, in the example code you forgot to instantiate
the $oForm object).

If you mean it isn't suitable to your needs, perhaps some more detailed
explanation of your exact needs are in order.

Grtz,
--
Rik Wasmus

**Ramon** · Jun 14 '06, 10:05 AM

Re: Calling a subclass's method

Ok,

thanks for your efforts Rik.
At least you gave me a way to make it work!

groetjes,
Ramon.

"Rik" <luiheidsgoeroe @hotmail.com> wrote in message
news:ec31e$448f ddc7$8259c69c$1 5457@news1.tude lft.nl...[color=blue]
> Ramon wrote:[color=green]
>> Thanks Rik,
>>
>> this does work.
>> I'm sorry that I keep asking, but I'm trying to understand this.
>>
>> I wonder if this is the correct way to address the $m_oTextBoxes
>> array. That array should be treated as if it were private, I
>> suppose..?[/color]
>
> In PHP4, it cannot be made private.
> An array in an object is just like any other array, so it's the correct
> way
> of adressing it.
>
>[color=green]
>> Actually, I should have an interface method to call this array:[/color]
>
> I've been trying some things, it seems it cannot be done in one line,
> except
> when using constructs like:
> call_user_func( array($oForm->getgetTextBoxB yID("Nr"), 'outerHTML));
>
> But I'm no real OOP programmer, maybe someone else could enlighten you.
>[color=green]
>> Then, I still have the question how to call the right instance of the
>> TextBox-class's getOuterHTML method.
>>
>> Because this will not work here: echo
>> $oForm->m_oTextBoxes["Nr"]->getOuterHTML() ;[/color]
>
> First it does work, now it doesn't work? Works perfectly here.
>
> If it actually doesn't work, try turning on error_reporting and var_dump()
> your objects. (For instance, in the example code you forgot to instantiate
> the $oForm object).
>
> If you mean it isn't suitable to your needs, perhaps some more detailed
> explanation of your exact needs are in order.
>
> Grtz,
> --
> Rik Wasmus
>
>[/color]

**Jerry Stuckle** · Jun 14 '06, 11:35 AM

Re: Calling a subclass's method

Ramon wrote:[color=blue]
> Thanks Rik,
>
> this does work.
> I'm sorry that I keep asking, but I'm trying to understand this.
>
> I wonder if this is the correct way to address the $m_oTextBoxes array.
> That array should be treated as if it were private, I suppose..?
>
> Actually, I should have an interface method to call this array:
>
>
> class HTMLForm {
> var $m_oTextBoxes = array();
>
>
> // Added method: =============== =============== ==========
>
> function getTextBoxByID( $sID) {
> return This->m_oTextBoxes[$sID];
> }
>
> // =============== =============== =============== =========
>
> function addTextBox($oTe xtBox) {
> $this->m_oTextBoxes[$oTextBox->getID()] = $oTextBox;
> }
>
> }
>
> Then, I still have the question how to call the right instance of the
> TextBox-class's getOuterHTML method.
>
> Because this will not work here: echo
> $oForm->m_oTextBoxes["Nr"]->getOuterHTML() ;
>
>
> Thanks for your patience!
> Ramon.
>[/color]

Ramon,

Yes, you should treat the array as private, even in PHP 4 where you can't
declare it such. One of the purposes of OO is to hide implementation details -
such as your data members.

The following (slightly modified from your previous post) works for me on PHP 5.1.2:

<?

class TextBox {
var $m_sID;
var $m_sName;
var $m_sValue;

// Class Constructor:
function TextBox ($sID, $sName, $sValue) {
$this->m_sID = $sID;
$this->m_sName = $sName;
$this->m_sValue = $sValue;
}

function getID() {
return $this->m_sID;
}

function getOuterHTML () {
return "<input type='text' name='" . $this->m_sName . "' value=' .
$this->m_sValue . '>";
}

}

class HTMLForm {
var $m_oTextBoxes = array();

function addTextBox($oTe xtBox) {
$this->m_oTextBoxes[$oTextBox->getID()] = $oTextBox;
}

function getTextBoxByID ($sID) {
return ($this->m_oTextBoxes[$sID]);
}
}

$oForm= new HTMLForm();
$oTxtNumber = new TextBox ("Nr", "Number", "123");
$oForm->addTextBox ($oTxtNumber);

echo $oForm->getTextBoxByID ("Nr")->getOuterHTML() ;

?>

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

**Rik** · Jun 14 '06, 12:15 PM

Re: Calling a subclass's method

Jerry Stuckle wrote:[color=blue]
> Yes, you should treat the array as private, even in PHP 4 where you
> can't
> declare it such. One of the purposes of OO is to hide implementation
> details - such as your data members.
>
> The following (slightly modified from your previous post) works for
> me on PHP 5.1.2:
>
> <snip code>[/color]

That's what I tried, but PHP4 has thsi to say about thes second ->:
Parse error: syntax error, unexpected T_OBJECT_OPERAT OR, expecting ',' or
';'

PHP5 indeed handles this with no problems.

Maybe this has something to do with returning by reference?

Grtz,
--
Rik Wasmus

**Markus Ernst** · Jun 14 '06, 12:55 PM

Re: Calling a subclass's method

Rik schrieb:[color=blue]
> That's what I tried, but PHP4 has thsi to say about thes second ->:
> Parse error: syntax error, unexpected T_OBJECT_OPERAT OR, expecting ',' or
> ';'
>
> PHP5 indeed handles this with no problems.
>
> Maybe this has something to do with returning by reference?[/color]

Indeed PHP4 passes objects by value (thus creates new instances), which
has been changed in PHP5. To pass references in PHP4 use the & character:

// & in function declaration to return reference
function &getTextBoxByID ($sID) {
return $this->m_oTextBoxes[$sID];
}

// & before parameter to pass it by reference
// & with = to assign reference
function addTextBox(&$oT extBox) {
$this->m_oTextBoxes[$oTextBox->getID()] =& $oTextBox;
}

HTH
Markus

**Jerry Stuckle** · Jun 14 '06, 04:45 PM

Re: Calling a subclass's method

Rik wrote:[color=blue]
> Jerry Stuckle wrote:
>[color=green]
>>Yes, you should treat the array as private, even in PHP 4 where you
>>can't
>>declare it such. One of the purposes of OO is to hide implementation
>>details - such as your data members.
>>
>>The following (slightly modified from your previous post) works for
>>me on PHP 5.1.2:
>>
>><snip code>[/color]
>
>
> That's what I tried, but PHP4 has thsi to say about thes second ->:
> Parse error: syntax error, unexpected T_OBJECT_OPERAT OR, expecting ',' or
> ';'
>
> PHP5 indeed handles this with no problems.
>
> Maybe this has something to do with returning by reference?
>
> Grtz,[/color]

Don't know - haven't used PHP 4 for ages. But as Markus pointed out, you can
return the object by reference.

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

Calling a subclass's method

Calling a subclass's method

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment

Comment