ob_list_handlers

List all output handlers in use

Description

array ob_list_handlers()

Lists all output handlers in use.

Parameters

This function has no parameters.

Return Values

This will return an array with the output handlers in use (if any).

If output_buffering is enabled and no output_handler is set, or no callback or null was passed to ob_start, "default output handler" is returned. Enabling output_buffering and setting an output_handler is equivalent to passing an internal (built-in) function to ob_start.

If a callable was passed to ob_start, the fully qualified name of the callable is returned. If the callable is an object implementing __invoke(), the fully qualified name of the object's __invoke() method is returned. If the callable is a Closure, "Closure::__invoke" is returned.

Examples

Example #1 ob_list_handlers example

<?php
// using output_buffering=On, no output_handler set
var_dump(ob_list_handlers());
ob_end_flush();

// no callback or null
ob_start();
var_dump(ob_list_handlers());
ob_end_flush();

// anonymous function
ob_start(function($string) { return $string; });
var_dump(ob_list_handlers());
ob_end_flush();

// arrow function
ob_start(fn($string) => $string);
var_dump(ob_list_handlers());
ob_end_flush();

// first class callable
$firstClassCallable = userDefinedFunction(...);

ob_start([$firstClassCallable, '__invoke']);
var_dump(ob_list_handlers());
ob_end_flush();

// internal (built-in) function
ob_start('print_r');
var_dump(ob_list_handlers());
ob_end_flush();

// user-defined function
function userDefinedFunction($string, $flags) { return $string; };

ob_start('userDefinedFunction');
var_dump(ob_list_handlers());
ob_end_flush();

class MyClass {
    public static function staticHandle($string) {
        return $string;
    }

    public static function handle($string) {
        return $string;
    }

    public function __invoke($string) {
        return $string;
    }
}

// class and static method
ob_start(['MyClass','staticHandle']);
var_dump(ob_list_handlers());
ob_end_flush();

// object and non-static method
ob_start([new MyClass,'handle']);
var_dump(ob_list_handlers());
ob_end_flush();

// invokable object
ob_start(new MyClass);
var_dump(ob_list_handlers());
ob_end_flush();
?>

The above example will output:

array(1) {
  [0]=>
  string(22) "default output handler"
}
array(1) {
  [0]=>
  string(22) "default output handler"
}
array(1) {
  [0]=>
  string(7) "print_r"
}
array(1) {
  [0]=>
  string(19) "userDefinedFunction"
}
array(1) {
  [0]=>
  string(17) "Closure::__invoke"
}
array(1) {
  [0]=>
  string(17) "Closure::__invoke"
}
array(1) {
  [0]=>
  string(17) "Closure::__invoke"
}
array(1) {
  [0]=>
  string(21) "MyClass::staticHandle"
}
array(1) {
  [0]=>
  string(15) "MyClass::handle"
}
array(1) {
  [0]=>
  string(17) "MyClass::__invoke"
}

ob_list_handlers

Description

Parameters

Return Values

Examples

See Also