Possible Duplicate:
php function overloading
I want to redeclare function such like this:
class Name{
function a(){ something; }
function a($param1){ something; }
}
but it returns
Fatal error: Cannot redeclare Name::a()
In java it just works. How can I do this in PHP?
Use default parameters:
class Name{
function a($param1=null){ something; }
}
If no parameter is passed to Name::a() it will assign a $param1 has a value of null. So basically passing that parameter becomes optional. If you need to know if it has a value or not you can do a simple check:
if (!is_null($param1))
{
//do something
}
You won't redeclare a function. Instead you can make an argument optional by assigning a default value to it. Like this:
function a($param1 = null){ something; }
Function arguments to not uniquely identify a function. In Java the arguments are strictly defined. This allows the compiler to know which function you are calling.
But, in PHP this is not the case.
function a()
{
$args = func_get_args();
foreach($args as $value)
{
echo $value;
}
}
It's possible to create function that has no arguments define, but still pass it arguments.
a("hello","world")
would output
hello world
As a result, PHP can't tell the different between a() and a($arg). Therefore, a() is already defined.
PHP programmers have different practices to handle this single function problem.
You can define an argument with default values.
a($arg = 'hello world');
You can pass mixed variable types.
function a($mixed)
{
if(is_bool($mixed))
{
.....
}
if(is_string($mixed))
{
.....
}
}
My preference is to use arrays with defaults. It's a lot more flexible.
function a($options=array())
{
$default = array('setting'=>true);
$options = array_merge($default,$options);
....
}
a(array('setting'=>false);
Unfortunately PHP does not support Method overloading like Java does. Have a look at this here for a solution: PHP function overloading
so func_get_args() is the way to go:
