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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[PHP] class constructor overloading
Hi, is it possible to overload the class construct(or) ? if yes, how ? thx. -- Alain Windows XP SP3 PostgreSQL 8.2.4 / MS SQL server 2005 Apache 2.2.4 PHP 5.2.4 C# 2005-2008
