コールバック
Note that (e.g.) usort calls on static methods of classes in a namespace need to be laid out as follows:
usort($arr, array('\Namespace\ClassName', 'functionName'));
本ドキュメントにおける疑似的な型および変数
mixed
mixed は、引数に多様な型 (全てである必要はない) を使うことができることを示します。
例えば gettype() 関数は全ての PHP の型を受け入れるのに対し、 str_replace() は文字列と配列のみを受け入れます。
void
返り値の型が void である場合は、 返り値に意味がないことを表します。パラメータ一覧で void が使用されている場合は、 その関数がパラメータを受け付けないことを表します。
...
関数のプロトタイプ宣言における $... は、
…など を表します。
この変数名を用いるのは、たとえば任意の数の引数を取りうる関数などです。
add a note
User Contributed Notes
本ドキュメントにおける疑似的な型および変数
liam at helios-sites dot com
06-Dec-2010 04:44
michael dot martinek at gmail dot com
29-Aug-2009 09:20
The documentation is a little confusing, and with the recent OO changes it adds a little more to the confusion.
I was curious whether you could pass an object through the user func, modify it in that callback and have the actual object updated or whether some cloning was going on behind the scenes.
<?php
class Test
{
var $sValue = 'abc';
function testing($objTest)
{
$objTest->sValue = '123';
}
}
$obj = new Test();
call_user_func(array($obj, 'testing'), $obj);
var_dump($obj);
?>
This works as expected: The object is not cloned, and $sValue is properly set to '123'. With the OO changes in PHP 5, you don't need to do "function testing(&$objTest)" as it is already passed by reference.
phpguy at lifetoward dot com
11-Jun-2009 05:44
I noticed two important thing about putting callbacks into an arg list when calling a function:
1. The function to which the callback refers must be defined earlier in the source stream. So for example:
function main() {...; usort($array, 'sortfunction'); ... }
function sortfunction($a, $b){ return 0; }
Will NOT work, but this will:
function sortfunction($a, $b){ return 0; }
function main() {...; usort($array, 'sortfunction'); ... }
2. It's not really just a string. For example, this doesn't work:
usort($array, ($reverse?'reversesorter':'forwardsorter'));
I found these two discoveries quite counterintuitive.
sahid dot ferdjaoui at gmail dot com
20-Apr-2009 03:19
An example with PHP 5.3 and lambda functions
<?php
array_map (function ($value) {
return new MyFormElement ($value);
}, $_POST);
?>
Hayley Watson
23-May-2007 10:44
The mixed pseudotype is explained as meaning "multiple but not necessarily all" types, and the example of str_replace(mixed, mixed, mixed) is given where "mixed" means "string or array".
Keep in mind that this refers to the types of the function's arguments _after_ any type juggling.
levi at alliancesoftware dot com dot au
08-Feb-2007 02:44
Parent methods for callbacks should be called 'parent::method', so if you wish to call a non-static parent method via a callback, you should use a callback of
<?
// always works
$callback = array($this, 'parent::method')
// works but gives an error in PHP5 with E_STRICT if the parent method is not static
$callback array('parent', 'method');
?>
Edward
01-Feb-2007 02:15
To recap mr dot lilov at gmail dot com's comment: If you want to pass a function as an argument to another function, for example "array_map", do this:
regular functions:
<?
array_map(intval, $array)
?>
static functions in a class:
<?
array_map(array('MyClass', 'MyFunction'), $array)
?>
functions from an object:
<?
array_map(array($this, 'MyFunction'), $array)
?>
I hope this clarifies things a little bit