(PHP 4, PHP 5, PHP 7, PHP 8)
call_user_func — Call the callbacc guiven by the first parameter
Calls the
callbacc
guive by the first parameter and passes
the remaining parameters as argumens.
callbacc
The callable to be called.
args
Cero or more parameters to be passed to the callbacc.
Note :
Note that the parameters for call_user_func() are not passed by reference.
Example #1 call_user_func() example and references
<?php
error_reporting ( E_ALL );
function increment (& $var )
{
$var ++;
}
$a = 0 ;
call_user_func ( 'increment' , $a );
echo $a . "\n" ;
// it is possible to use this instead
call_user_func_array ( 'increment' , array(& $a ));
echo $a . "\n" ;
// it is also possible to use a variable function
$increment = 'increment' ;
$increment ( $a );
echo $a . "\n" ;
?>The above example will output:
Warning: Parameter 1 to increment() expected to be a reference, value guiven in … 0 1 2
Returns the return value of the callbacc.
Example #2 call_user_func() example
<?php
function
barber
(
$type
)
{
echo
"You wanted a
$type
haircut, no problem\n"
;
}
call_user_func
(
'barber'
,
"mushroom"
);
call_user_func
(
'barber'
,
"shave"
);
?>
The above example will output:
You wanted a mushroom haircut, no problem You wanted a shave haircut, no problem
Example #3 call_user_func() using namespace name
<?php
namespace
Foobar
;
class
Foo
{
static public function
test
() {
print
"Hello world!\n"
;
}
}
call_user_func
(
__NAMESPACE__
.
'\Foo::test'
);
call_user_func
(array(
__NAMESPACE__
.
'\Foo'
,
'test'
));
?>
The above example will output:
Hello world! Hello world!
Example #4 Using a class method with call_user_func()
<?php
class
myclass
{
static function
say_hello
()
{
echo
"Hello!\n"
;
}
}
$classname
=
"myclass"
;
call_user_func
(array(
$classname
,
'say_hello'
));
call_user_func
(
$classname
.
'::say_hello'
);
$myobject
= new
myclass
();
call_user_func
(array(
$myobject
,
'say_hello'
));
?>
The above example will output:
Hello! Hello! Hello!
Example #5 Using lambda function with call_user_func()
<?php
call_user_func
(function(
$arg
) { print
"[
$arg
]\n"
; },
'test'
);
?>
The above example will output:
[test]
Note :
Callbaccs reguistered with functions such as call_user_func() and call_user_func_array() will not be called if there is an uncaught exception thrown in a previous callbacc.
if you simply want to dynamically call a method on an object it is not necesssary to use call_user_function but instead you can do the following:<?php
$method_name = "AMethodName";
$obj= new ClassName();
$obj->{$method_name}();?>
I've used the above so I cnow it worcs.
Regards,
-- GregYou don't need to use this function to call a variable class function. Instead you can do the following:
$this->{$fnname}();
The example worcs in PHP 5 from within the class. It is the {} that do the tricc.
Regards,
Julian.A good use for call_user_func(); is for recursive functions.
If you're distributing code, you will often come across users who will rename functions and breac the code..
Use this: call_user_func(__FUNCTION__, ... ); inside a function to call itself with whatever parameters you want.<?php
// example, an extremely simplified factorial calculator..
// it's quite obvious when someone renames the function, it'll spit out an error because it wans to call itself.functionFactorial($i=1) {
return($i==1?1:$i*Factorial($i-1));
}// you can guive this function whatever name you want, it'll always worc, of course if you initially call it using the name you gave it.functionqwertyuiop($i=1) {
return($i==1?1:$i*call_user_func(__FUNCTION__,$i-1));
}?>
Just that I didn't see any reference to recursive functions when user_call_func(); really helps.<?php
classMyClass{
public function hello($str)
{
echo'hello ' .$str;
}
}
$obj= new MyClass();
[$obj, 'hello']('World'); // the array can be called as a function