Re: [PHP] class constructor overloading
>> is it possible to overload the class construct(or) ?
>> if yes, how ?
No, it's not.
> class A
> {
>function __construct()
>{
>echo "A";
>}
> }
>
> class B extends A
> {
>function __construct()
>{
>echo "B";
>parent::__construct();
>}
> }
> $B = new B();
The above is an example of overriding, not overloading; PHP allows the
former but not the latter.
Examples of overloading include:
class A
{
function myFunc( $boolean )
{
}
function myFunc( $string )
{
}
function myFunc( $array )
{
}
}
Because PHP is loosely typed, the above is largely moot/unnecessary.
class B
{
function myFunc( $boolean )
{
}
function myFunc( $boolean, $string )
{
}
function myFunc( $boolean, $string, $array )
{
}
}
PHP allows you to get around the above by allowing you to define
default values for arguments. Doing that is kind of like overloading
but only in a fake-me-out kind of way. So instead of overloading the
myFunc method, you could just define it as follows:
class B
{
function myFunc( $boolean = FALSE, $string = '', $array = array())
{
}
}
but even that doesn't ensure that the data type of each argument is as
you might expect. As I stated above, PHP is loosely typed so there is
nothing preventing, say, the $string argument from actually being a
numeric datatype. If you are using PHP5+, you can sort of get around
that by using type hinting
(http://us.php.net/manual/en/language.oop5.typehinting.php) but you
can only type hint objects and arrays.
In closing, to answer your question,
Overriding: yes
Overloading: no
thnx,
Chris
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Re: [PHP] class constructor overloading
Alain Roger schreef:
> thanks a lot, this is exactly what i needed.
> if the construct of based class A accept arguments, i guess that construct
> of class B must have the sames.
> moreover, i guess that something like that must be written:
I guess you find guessing preferable to RTFM and/or trying code out.
> class A
> {
> function __construct($nameA)
> {
> ...
> }
> }
>
> class B extends A
> {
> function __construct($nameB)
> {
> parent::__construct($nameB);
> }
> }
>
> am i right ?
are you?
>
> thanks.
>
> A.
>
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Re: [PHP] class constructor overloading
2008/10/23 Alain Roger <[EMAIL PROTECTED]>:
> thanks a lot, this is exactly what i needed.
> if the construct of based class A accept arguments, i guess that construct
> of class B must have the sames.
No, you can change the signature of a method when you overload it.
Below, B::__construct() accepts 1 argument while A::__construct()
accepts 0 arguments:
class A
{
function __construct()
{
echo "A";
}
}
class B extends A
{
function __construct( $string )
{
echo $string;
parent::__construct();
}
}
$B = new B( "B" );
If you need to force a certain signature in child classes, you can
declare the parent class abstract:
abstract class A
{
abstract function f( $a );
}
class B extends A
{
function f( $a, $b ) // throws an error
{
echo "$a, $b";
}
}
$B = new B("B", "C");
However, if you declare the constructor as abstract, it will be ignored.
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Re: [PHP] class constructor overloading
Alain Roger wrote:
thanks a lot, this is exactly what i needed.
if the construct of based class A accept arguments, i guess that construct
of class B must have the sames.
moreover, i guess that something like that must be written:
class A
{
function __construct($nameA)
{
...
}
}
class B extends A
{
function __construct($nameB)
{
parent::__construct($nameB);
}
}
am i right ?
thanks.
A.
Yes
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Re: [PHP] class constructor overloading
thanks a lot, this is exactly what i needed.
if the construct of based class A accept arguments, i guess that construct
of class B must have the sames.
moreover, i guess that something like that must be written:
class A
{
function __construct($nameA)
{
...
}
}
class B extends A
{
function __construct($nameB)
{
parent::__construct($nameB);
}
}
am i right ?
thanks.
A.
Re: [PHP] class constructor overloading
2008/10/23 Alain Roger <[EMAIL PROTECTED]>:
> is it possible to overload the class construct(or) ?
> if yes, how ?
class A
{
function __construct()
{
echo "A";
}
}
class B extends A
{
function __construct()
{
echo "B";
parent::__construct();
}
}
$B = new B();
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Re: [PHP] Class constructor
On 31 Jan 2006, at 13:52, David Grant wrote:
Drop __construct, PHP5 will call Test() anyway.
From http://uk.php.net/manual/en/language.oop5.decon.php:
"For backwards compatibility, if PHP 5 cannot find a __construct()
function for a given class, it will search for the old-style
constructor
function, by the name of the class."
Sure, if you're planning on writing 'backwards' code for ever more...
For maximum efficiency in PHP5, do it this way around:
class test{
function Test(){
$this->__construct()
//This will be called in PHP4
}
function __construct(){
//This will be called in PHP5
}
}
Why penalise the platform you're intending to run it on?
Marcus
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Re: [PHP] Class constructor
On Tue, January 31, 2006 7:46 am, Georgi Ivanov wrote:
> I'm writing a simple class. In order to be compatible with php4 and
> php5 I've
> done this :
>
> class test{
> function Test(){
> //This will be called in PHP4
> }
> function __construct(){
> //This will be called in PHP5
> $this->Test();
> }
> }
>
> Is this a solution ? Is there a better way ?
I suppose if you want the code to run under PHP6, 7, 8, 9, 10, ... it
is somewhat forward-looking to the potential day when Test::Test()
might no longer work as the constructor...
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Re: [PHP] Class constructor
Yes, I noticed that PHP5 call the old way constructor, but what if in future version they drop this feature ? I think this is workaround for the problem . Or not ? On Tuesday January 31 2006 15:52, David Grant wrote: > Georgi, > > Drop __construct, PHP5 will call Test() anyway. > > >From http://uk.php.net/manual/en/language.oop5.decon.php: > > "For backwards compatibility, if PHP 5 cannot find a __construct() > function for a given class, it will search for the old-style constructor > function, by the name of the class." > > David > -- > David Grant > http://www.grant.org.uk/ > > http://pear.php.net/package/File_Ogg0.2.1 > http://pear.php.net/package/File_XSPF 0.1.0 > > WANTED: Junior PHP Developer in Bristol, UK -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Class constructor
Georgi, Drop __construct, PHP5 will call Test() anyway. >From http://uk.php.net/manual/en/language.oop5.decon.php: "For backwards compatibility, if PHP 5 cannot find a __construct() function for a given class, it will search for the old-style constructor function, by the name of the class." David -- David Grant http://www.grant.org.uk/ http://pear.php.net/package/File_Ogg0.2.1 http://pear.php.net/package/File_XSPF 0.1.0 WANTED: Junior PHP Developer in Bristol, UK -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Class constructor
You could try with phpversion().
Georgi Ivanov wrote:
Hi,
I'm writing a simple class. In order to be compatible with php4 and php5 I've
done this :
class test{
function Test(){
//This will be called in PHP4
}
function __construct(){
//This will be called in PHP5
$this->Test();
}
}
Is this a solution ? Is there a better way ?
Thanks.
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Re: [PHP] class constructor & polymorphism
[EMAIL PROTECTED] wrote: Hi to all, I'm a C++ programmer and I've to convert some simple classes from C++ to PHP. My toolbar_button class must have two or more constructors so I ask you if this is possible with PHP: You can't overload a constructor, I mean a function in PHP. Maybe extending two classes from the base would be a good work-around. Hope this helps, -- Josip Dzolonga http://josip.dotgeek.org jdzolonga[at]gmail.com -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
