Whilst it was correct 11 years ago, the statement of Dan D is not so correct any moreю Anonymous functions are now objects of a class Closure and are safely collected by garbage collector.
create_function
(PHP 4 >= 4.0.1, PHP 5, PHP 7)
create_function — 文字列のコードを評価し、動的に関数を作成する
警告
この関数は PHP 7.2.0 で 非推奨 になり、PHP 8.0.0 で 削除 されました。この関数に頼らないことを強く推奨します。
説明
create_function(string
$args, string $code): string指定したパラメータにより動的に関数を作成し、その関数のユニークな名前を返します。
パラメータ
通常、argsには、シングルクオートで括った文字列 を
指定することが推奨されます。
ダブルクオート を使用した場合には、\$somevarのように変数名を
注意深くエスケープする必要があります。
-
args -
関数の引数を、カンマ区切りの文字列で指定します。
-
code -
関数のコード。
戻り値
一意な関数名を表す文字列を返します。
失敗した場合に false を返します。
返される名前には、
印字できない文字("\0")
が含まれているので注意して下さい。
よって、この名前を出力したり、
他の文字列に組み込む場合は特別な注意を払うべきです。
例
例1 create_function() や無名関数を使い、動的に関数を作成する
(たとえば) 実行時に取得した情報をもとにして関数を作成するために、動的に作成した関数が使えます。まず create_function() を使ってみます:
<?php
$newfunc = create_function('$a,$b', 'return "ln($a) + ln($b) = " . log($a * $b);');
echo $newfunc(2, M_E) . "\n";
?>同じコードは、無名関数 でも実現できます。コードや引数は、文字列に含まれていない点に注意して下さい:
<?php
$newfunc = function($a,$b) { return "ln($a) + ln($b) = " . log($a * $b); };
echo $newfunc(2, M_E) . "\n";
?>上の例の出力は以下となります。
ln(2) + ln(2.718281828459) = 1.6931471805599
例2 create_function() や無名関数を使い、一般的な処理を行う関数を作成する
もしくは、パラメータリストに一連の処理を行うことができる 一般的なハンドラ関数を定義できます:
<?php
function process($var1, $var2, $farr)
{
foreach ($farr as $f) {
echo $f($var1, $var2) . "\n";
}
}
// 数学関数群を作成します
$farr = array(
create_function('$x,$y', 'return "some trig: ".(sin($x) + $x*cos($y));'),
create_function('$x,$y', 'return "a hypotenuse: ".sqrt($x*$x + $y*$y);'),
create_function('$a,$b', 'if ($a >=0) {return "b*a^2 = ".$b*sqrt($a);} else {return false;}'),
create_function('$a,$b', "return \"min(b^2+a, a^2,b) = \".min(\$a*\$a+\$b,\$b*\$b+\$a);"),
create_function('$a,$b', 'if ($a > 0 && $b != 0) {return "ln(a)/b = ".log($a)/$b; } else { return false; }')
);
echo "\nUsing the first array of dynamic functions\n";
echo "parameters: 2.3445, M_PI\n";
process(2.3445, M_PI, $farr);
// 文字列処理関数群を作成します
$garr = array(
create_function('$b,$a', 'if (strncmp($a, $b, 3) == 0) return "** \"$a\" '.
'and \"$b\"\n** Look the same to me! (looking at the first 3 chars)";'),
create_function('$a,$b', 'return "CRCs: " . crc32($a) . ", ".crc32($b);'),
create_function('$a,$b', 'return "similar(a,b) = " . similar_text($a, $b, $p) . "($p%)";')
);
echo "\nUsing the second array of dynamic functions\n";
process("Twas brilling and the slithy toves", "Twas the night", $garr);
?>ここでも、 同じことが 無名関数 で実現できます。 変数名をエスケープする必要がないことに注意して下さい。 なぜなら、文字列に埋め込まれていないからです。
<?php
function process($var1, $var2, $farr)
{
foreach ($farr as $f) {
echo $f($var1, $var2) . "\n";
}
}
// 数学関数群を作成します
$farr = array(
function($x,$y) { return "some trig: ".(sin($x) + $x*cos($y)); },
function($x,$y) { return "a hypotenuse: ".sqrt($x*$x + $y*$y); },
function($a,$b) { if ($a >=0) {return "b*a^2 = ".$b*sqrt($a);} else {return false;} },
function($a,$b) { return "min(b^2+a, a^2,b) = " . min($a*$a+$b, $b*$b+$a); },
function($a,$b) { if ($a > 0 && $b != 0) {return "ln(a)/b = ".log($a)/$b; } else { return false; } }
);
echo "\nUsing the first array of dynamic functions\n";
echo "parameters: 2.3445, M_PI\n";
process(2.3445, M_PI, $farr);
// 文字列処理関数群を作成します
$garr = array(
function($b,$a) { if (strncmp($a, $b, 3) == 0) return "** \"$a\" " .
"and \"$b\"\n** Look the same to me! (looking at the first 3 chars)"; },
function($a,$b) { return "CRCs: " . crc32($a) . ", ".crc32($b); },
function($a,$b) { return "similar(a,b) = " . similar_text($a, $b, $p) . "($p%)"; }
);
echo "\nUsing the second array of dynamic functions\n";
process("Twas brilling and the slithy toves", "Twas the night", $garr);
?>上の例の出力は以下となります。
Using the first array of dynamic functions parameters: 2.3445, M_PI some trig: -1.6291725057799 a hypotenuse: 3.9199852871011 b*a^2 = 4.8103313314525 min(b^2+a, a^2,b) = 8.6382729035898 ln(a)/b = 0.27122299212594 Using the second array of dynamic functions ** "Twas the night" and "Twas brilling and the slithy toves" ** Look the same to me! (looking at the first 3 chars) CRCs: 3569586014, 342550513 similar(a,b) = 11(45.833333333333%)
例3 動的な関数をコールバック関数として使う
おそらく、動的な関数のもっとも一般的な用途は、コールバックに渡すことでしょう。 たとえば array_walk() あるいは usort() などで使用します。
<?php
$av = array("the ", "a ", "that ", "this ");
array_walk($av, create_function('&$v,$k', '$v = $v . "mango";'));
print_r($av);
?>無名関数 を使うと、下記のようになります:
<?php
$av = array("the ", "a ", "that ", "this ");
array_walk($av, function(&$v,$k) { $v = $v . "mango"; });
print_r($av);
?>上の例の出力は以下となります。
Array ( [0] => the mango [1] => a mango [2] => that mango [3] => this mango )
create_function() を使い、文字列を長いものから短いものに並べます:
<?php
$sv = array("small", "a big string", "larger", "it is a string thing");
echo "Original:\n";
print_r($sv);
echo "Sorted:\n";
usort($sv, create_function('$a,$b','return strlen($b) - strlen($a);'));
print_r($sv);
?>無名関数 を使うと、下記のようになります:
<?php
$sv = array("small", "a big string", "larger", "it is a string thing");
echo "Original:\n";
print_r($sv);
echo "Sorted:\n";
usort($sv, function($a,$b) { return strlen($b) - strlen($a); });
print_r($sv);
?>上の例の出力は以下となります。
Original: Array ( [0] => small [1] => a big string [2] => larger [3] => it is a string thing ) Sorted: Array ( [0] => it is a string thing [1] => a big string [2] => larger [3] => small )
add a note
User Contributed Notes 32 notes
tamagochi_man ¶
4 years ago
Dan D ¶
16 years ago
Beware when using anonymous functions in PHP as you would in languages like Python, Ruby, Lisp or Javascript. As was stated previously, the allocated memory is never released; they are not objects in PHP -- they are just dynamically named global functions -- so they don't have scope and are not subject to garbage collection.
So, if you're developing anything remotely reusable (OO or otherwise), I would avoid them like the plague. They're slow, inefficient and there's no telling if your implementation will end up in a large loop. Mine ended up in an iteration over ~1 million records and quickly exhasted my 500MB-per-process limit.
kak dot serpom dot po dot yaitsam at gmail dot com ¶
11 years ago
Try this to boost performance of your scripts (increase maxCacheSize):
<?php
runkit_function_copy('create_function', 'create_function_native');
runkit_function_redefine('create_function', '$arg,$body', 'return __create_function($arg,$body);');
function __create_function($arg, $body) {
static $cache = array();
static $maxCacheSize = 64;
static $sorter;
if ($sorter === NULL) {
$sorter = function($a, $b) {
if ($a->hits == $b->hits) {
return 0;
}
return ($a->hits < $b->hits) ? 1 : -1;
};
}
$crc = crc32($arg . "\\x00" . $body);
if (isset($cache[$crc])) {
++$cache[$crc][1];
return $cache[$crc][0];
}
if (sizeof($cache) >= $maxCacheSize) {
uasort($cache, $sorter);
array_pop($cache);
}
$cache[$crc] = array($cb = eval('return function('.$arg.'){'.$body.'};'), 0);
return $cb;
}
?>
kkaiser at revolution-records dot net ¶
16 years ago
In the process of migrating a PHP4 codebase to PHP5, I ran into a peculiar problem. In the library, every class was derived from a generic class called 'class_container'. 'class_container' contained an array called runtime_functions and a method called class_function that was as follows:
<?php
function class_function($name,$params,$code) {
$this->runtime_functions[$name] = create_function($params,$code);
}
?>
In a subclass of class_container, there was a function that utilized class_function() to store some custom lambda functions that were self-referential:
<?php
function myfunc($name,$code) {
$this->class_function($name,'$theobj','$this=&$theobj;'.$code);
}
?>
In PHP4, this worked just fine. The idea was to write blocks of code at the subclass level, such as "echo $this->id;", then simply $MYOBJ->myfunc("go","echo $this->id;"); and later call it like $MYOBJ->runtime_functions["go"]();
It essentially worked exactly like binding anonymous functions to objects in Javascript.
Note how the "$this" keyword had to be manually redefined for the $code block to work.
In PHP5, however, you can't redeclare $this without getting a fatal error, so the code had to be updated to:
<?php
function myfunc($name,$code) {
$this->class_function($name,'$this',$code);
}
?>
Apparently create_function() allows you to set $this via a function argument, allowing you to bind anonymous functions to instantiated objects. Thought it might be useful to somebody.
info at adaniels dot nl ¶
17 years ago
Note that using __FUNCTION__ in a an anonymous function, will always result '__lambda_func'.
<?php
$fn = create_function('', 'echo __FUNCTION__;');
$fn();
// Result: __lambda_func
echo $fn;
// Result: ºlambda_2 (the actual first character cannot be displayed)
?>
This means that a anonymous function can't be used recursively. The following code (recursively counting to 10) results in an error:
<?php
$fn2 = create_function('$a', 'echo $a; if ($a < 10) call_user_func(__FUNCTION__, $a++);');
$fn2(1);
// Warning: call_user_func(__lambda_func) [function.call-user-func]: First argument is expected to be a valid callback in T:/test/test.php(21) : runtime-created function on line 1
?>
Josh J ¶
16 years ago
In regards to the recursion issue by info at adaniels dot nl
Anon function recursion by referencing the function variable in the correct scope.
<?php
$fn2 = create_function('$a', 'echo $a; if ($a < 10) call_user_func($GLOBALS["fn2"], ++$a);');
$fn2(1);
?>
lombax85 at gmail dot com ¶
2 years ago
For who *really* needs the create_function() on php8 (because of legacy code that cannot be changed easily) there is this: "composer require lombax85/create_function".
Rene Saarsoo ¶
15 years ago
Here has been some discussion about the "memory leak" create_function() can create.
What create_function() actually does, is creating an ordinary function with name chr(0).lambda_n where n is some number:
<?php
$f = create_function('', 'return 1;');
function lambda_1() { return 2; }
$g = "lambda_1";
echo $g(); // outputs: 2
$h = chr(0)."lambda_1";
echo $h(); // outputs: 1
?>
CertaiN ¶
10 years ago
Best wapper:
<?php
function create_lambda($args, $code) {
static $func;
if (!isset($func[$args][$code])) {
$func[$args][$code] = create_function($args, $code);
}
return $func[$args][$code];
}
Dave H ¶
12 years ago
The following function is very useful for creating an alias of a user function.
For built-in functions, it is less useful because default values are not available, so function aliases for built-in functions must have all parameters supplied, whether optional or not.
<?php
function create_function_alias($function_name, $alias_name)
{
if(function_exists($alias_name))
return false;
$rf = new ReflectionFunction($function_name);
$fproto = $alias_name.'(';
$fcall = $function_name.'(';
$need_comma = false;
foreach($rf->getParameters() as $param)
{
if($need_comma)
{
$fproto .= ',';
$fcall .= ',';
}
$fproto .= '$'.$param->getName();
$fcall .= '$'.$param->getName();
if($param->isOptional() && $param->isDefaultValueAvailable())
{
$val = $param->getDefaultValue();
if(is_string($val))
$val = "'$val'";
$fproto .= ' = '.$val;
}
$need_comma = true;
}
$fproto .= ')';
$fcall .= ')';
$f = "function $fproto".PHP_EOL;
$f .= '{return '.$fcall.';}';
eval($f);
return true;
}
?>
edgar at goodforall dot eu ¶
14 years ago
Just a little toy I thought up, I would like to share. Creates an anonymous function, which let you use a class as a function.
In php 5.3 there is support for real functors (trough __invoke):
<?php
function createFunctor($className){
$content = "
static \$class;
if(!\$class){
\$class = new $className;
}
return \$class->run(\$args);
";
$f = create_function('$args', $content);
return $f;
}
class test {
public function run($args){
print $args;
}
}
$test = createFunctor('test');
$test('hello world');
?>
neo at nowhere dot com ¶
15 years ago
In response to kkaiser at revolution-records dot net's note, even tho PHP will allow you to use
<?
$myfunc = create_function('$this', $code);
?>
You can NOT use a reference to "$this" inside of the anonymous function, as PHP will complain that you are using a reference to "$this" in a non-object context.
Currently, I have not found a work-around for this...
Alan FUNG ¶
15 years ago
$f = create_function('','echo "function defined by create_function";');
$f();
result:
function defined by create_function
You may define no return in function body while you are using create_function.
TSE-WebDesign ¶
16 years ago
Here's how to call a runtime-created function from another runtime-created function:
<?php
$get_func = create_function('$func', 'return substr($func,1);');
$get_value = create_function('$index','return pow($index,$index);');
$another_func = create_function('$a', '$func="\x00"."'.$get_func($get_value).'";return $func($a);');
echo $another_func(2); # result is 4
?>
Phlyst ¶
16 years ago
In reply to info at adaniels dot nl:
You may not be able to use __FUNCTION__ in a lambda (thanks for pointing it out; I was having that problem just now), but you can use $GLOBALS to work around it if you're assigning the function to a variable. I reimplemented array_walk_recursive() in PHP4 like this:
<?php
$array_walk_recursive = create_function('&$array, $callback',
'foreach($array as $element) {
if(is_array($element)) {
$funky = $GLOBALS["array_walk_recursive"];
$funky($element, $callback);
}
else {
$callback($element);
}
}');
?>
josh at janrain dot com ¶
17 years ago
Beware! This is merely a convenience function that generates a unique name for a regular function. It is *not* a closure or even an anonymous function. It is just a regular function that gets named for you.
Joshua E Cook ¶
17 years ago
Functions created by create_function() cannot return a value by reference. The function below creates a function that can. The arguments are the same as create_function(). Note that these arguments are passed, unmodified, to eval(), so be sure that data passed in is sanitized.
<?php
/**
* create_ref_function
* Create an anonymous (lambda-style) function
* which returns a reference
* see http://php.net/create_function
*/
function
create_ref_function( $args, $code )
{
static $n = 0;
$functionName = sprintf('ref_lambda_%d',++$n);
$declaration = sprintf('function &%s(%s) {%s}',$functionName,$args,$body);
eval($declaration);
return $functionName;
}
?>
boards at gmail dot com ¶
17 years ago
If you were checking to see if a function is made properly, this would be a better way of checking:
<?php
$fnc = @create_function('$arg1,$arg2,$arg3', 'return true;');
# make that function whatever you want
if (empty($fnc)) {
die('Could not create function $fnc.');
}
# although, the follow will NOT work
if (empty(create_function('$arg', 'return $arg;'))) {
die('Could not create anonymous function.');
}
# you would get an error regarding not being able to use a
# return value in writeable context (i.e. a return value is
# a const in C, and the function empty() doesn't use a
# const void* parameter
?>
neo at gothic-chat d0t de ¶
19 years ago
Beware of memory-leaks, the garbage-collection seems to 'oversee' dynamically created functions!
I used a function like this to replace special characters in links with their htmlentities:
<?php
$text = preg_replace_callback (
"/(<(frame src|a href|form action)=\")([^\"]+)(\"[^>]*>)/i",
create_function (
'$matches',
'return $matches[1] . htmlentities ($matches[3]) . $matches[4];'
),
$text);
?>
After 1000 calls, the process used about 5MB more than before. In my situation this boosted up the memory-size of one PHP-process up to over 100MB!
In such cases, better store the function in a global variable.
DB on music_ml at yahoo dot com dot ar ¶
20 years ago
[EDIT by danbrown AT php DOT net: Combined user-corrected post with previous (incorrect) post.]
You can't refer to a class variable from an anonymous function inside a class method using $this. Anonymous functions don't inherit the method scope. You'll have to do this:
<?php
class AnyClass {
var $classVar = 'some regular expression pattern';
function classMethod() {
$_anonymFunc = create_function( '$arg1, $arg2', 'if ( eregi($arg2, $arg1) ) { return true; } else { return false; } ' );
$willWork = $_anonymFunc('some string', $classVar);
}
}
?>
x-empt[a_t]ispep.cx ¶
22 years ago
Create_function enables the ability to change the scope of functions. You might have a class where it needs to define a GLOBAL function. This is possible, like:
<?php
class blah {
function blah() {
$z=create_function('$arg1string','return "function-z-".$arg1string;');
$GLOBALS['z']=$z;
}
}
$blah_object=new blah;
$result=$GLOBALS['z']('Argument 1 String');
echo $result;
?>
Making a function escape it's defined scope can be useful in many situations.
koyama at hoge dot org ¶
22 years ago
How do you use function which is created by create_function() as class method?
<?php
class Hoge {
var $lamda;
function set($lamda) {
$this->lamda = $lamda;
}
function callLamda() {
$func = $this->lamda;
return $func();
}
}
$newfunc = create_function('', 'echo "hoge<br>\n";');
$h = new Hoge;
$h->set( $newfunc );
$h->callLamda();
?>
It works fine. :-)
tomas dot vot at gmail dot com ¶
4 years ago
If you need to upgrade more than one `create_function` to anonymous function, I'm working on a tool that makes dev's life much easier and adaptable for new versions of anything in PHP.
It's tested on 30+ various (and really weird :)) cases, like:
-$callback = create_function('$a', 'return "<cas:proxy>$a</cas:proxy>";');
+$callback = function ($a) {
+ return "<cas:proxy>{$a}</cas:proxy>";
+};
Includes concat (.), string quotes and inclined function calls:
-$func = create_function('$atts, $content = null','return "<div class=\"' . $class_list . '\">" . do_shortcode($content) . "</div>";' );
+$func = function ($atts, $content = null) use ($class_list) {
+ return "<div class=\"{$class_list}\">" . do_shortcode($content) . "</div>";
+};
Do you want to automate the hard work?
1. Instal Rector
composer require rector/rector --dev
2. Create config
# rector.yml
services:
Rector\Php\Rector\FuncCall\CreateFunctionToAnonymousFunctionRector: ~
3. Upgrade your Code
vendor/bin/rector process src --config rector.yml --dry-run
vendor/bin/rector process src --config rector.yml
CertaiN ¶
10 years ago
How to save memory-space:
<?php
function create_lambda($args, $code) {
static $list = array();
$i = "{$args}\0{$code}";
if (!isset($list[$i])) {
$list[$i] = create_function($args, $code);
}
return $list[$i];
}
Its Will ¶
13 years ago
If you create a function that will only be used from an object context (i.e. you want a dynamic method that can then call methods from the original object, still maintaining access to the object's runtime values) then you can use the following functions I have created (ob_lambda_func and ob_lambda) to enable the dynamic function to easily call *public* methods on the object, in their runtime contexts:
<?php
/* the OB Lambda functions allow a lambda function to call a method from its callee's object */
if(!function_exists('ob_lambda_func')){
function ob_lambda_func($method, $args) {
if((phpversion()+0)<5.1 || (substr(phpversion(),2)+0)<1.1)
die("\nError: This script requires PHP v5.1.1+!\n");
$bt=debug_backtrace();
foreach($bt as $xsp) {
if(isset($xsp['object'])) {
if(!method_exists($xsp['object'], $method)) continue;
return call_user_func_array(array($xsp['object'], $method), $args);
}
}
if(!function_exists($method))
die("\nOB: Internal Error! ($method)");
return call_user_func_array($method, $args);
}}
if(!function_exists('ob_lambda')){
function ob_lambda($method) {
return create_function('','$args=func_get_args(); return ob_lambda_func('.var_export($method, true).',$args);');
}}
/* Usage:
* For each callable method, store the results of ob_lambda('method_name')
* When a lambda function you call wants to access one of these methods,
* you need to pass it the result of ob_lambda for that method, the easiest
* way is to have one of the lambda functions arguments accept the result
* i.e.: $myFunc=ob_lambda('myMethod');
* $lf1=create_function('$func', '$func( ... args ... )');
* $lf1($myFunc);
* because create_function prepends a \0 to the function name, it is difficult
* to pass the result of ob_lambda to the target function without using an argument
*/
/* here is an example -- lambda function Foo::test can call Foo::Bar and Foo::Baz, and these */
class Foo {
private $bar, $baz, $test;
private $runtimeValue=0;
function __construct() {
$this->runtimeValue=rand();
$this->bar=ob_lambda('Bar');
$this->baz=ob_lambda('Baz');
$this->test=create_function(
'$bar, $baz',
'$bar("Hello, World!"); $baz();'
);
}
function Test() {
$fn=$this->test;
$fn($this->bar, $this->baz);
}
function Bar($a) {
echo "$a: Bar ($this->runtimeValue)\n";
}
function Baz() {
echo "and another! Baz ($this->runtimeValue)\n";
}
}
$foo=new Foo();
// Foo::Bar("Testing Other Method"); <-- this causes fatal error
// (using $this when not in object context)
$foo->Test();
?>
This snippet (with test) shows how the lambda function $foo->test can call Foo::Bar and Foo::Baz without an explicit reference to the original object. The methods are run from their object context, and so can access the runtime-modified variable $foo->runtimeValue, which is set to a random number on construction.
The function definition for $foo->test is the following:
function ($bar, $baz) {
$bar("Hello, World!");
$baz;
}
As you can see, it is clean and simple, with no obvious artifacts from the use of OB Lambda
The expected output should be:
Hello, World!: Bar (440048505)
and another! Baz (440048505)
Or any other random number in place of 440048505
Make sure, before you change your code, that your target server has PHP 5.1.1+, or these functions won't work and will return an error!
Hope this helps anyone as much as it has me! :)
v dot churakov at i2d dot ru ¶
13 years ago
<?
function is_function( &$mixed )
{
if ( is_object( $mixed ) ) {
return ( $mixed instanceof Closure );
} elseif( is_string( $mixed ) ) {
return function_exists( $mixed );
} else {
return false;
}
}
function myfunc(){}
$test = 123;
echo is_function( $test ); //will return false
$test = 'isset';
echo is_function( $test ); //will return false... it's not work with reserved :( ...
$test = 'myfunc';
echo is_function( $test ); //will return true
$test = create_function( '', 'echo 123;' );
echo is_function( $test ); //will return true
$test = function () { echo 123; };
echo is_function( $test ); //will return true
?>
ionix at NOSPAM dot post dot com ¶
10 years ago
I experimented a bit in creating a lambda function using a variable amount of arguments. While I couldn't find an efficient way to create a random bit of code, I was able to get it to behave as a front end for existing functions (as well as user-defined of course).
The code required me to use the dreaded eval() function to get it to use a variable amount of parameters, so be sure that all input is thoroughly cleaned if derived from the user.
<?php
function run_function( $function )
{
// Get Arguments, Unset Exisitng Parameter
$params = func_get_args();
unset( $params[0] );
if( ( $count = count( $params ) ) > 0 )
{
$args = '$a';
$inc = 'b';
// Create Argument String - Formats as '$a, $b, $c' Per Number of Arguments
for( $x = 1; $x < $count; $x++ )
{
$args .= ', $' . $inc;
$inc++;
}
// Create Lambda Function and Format Paramters
$lambda = create_function( $args, 'return ' . $function . '(' . $args . ');' );
$params = "'" . implode('\', \'', $params) . "'";
// Build and Evaluate Function with Parameters
$eval = '$return = $lambda(' . $params . ');';
eval($eval);
return $return;
}
else
{
return false;
}
}
?>
For most applications you would be better off calling the function normally. Perhaps this little proof of concept may find some use if adapted to work by someone who requires it.
131 dot php at cloudyks dot org ¶
11 years ago
For those who want to create closure with create_function, don't bother, you can't.
Use create_closure instead :p
<?php
//same thing as create_function, but returns a closure..( 5.4)
function create_closure($args, $body){
return eval("return function($args){ {$body} };");
}
?>
MagicalTux at FF.ST ¶
19 years ago
neo at gothic-chat d0t de wrote :
Beware of memory-leaks, the garbage-collection seems to 'oversee' dynamically created functions!
Not really...
In fact, PHP can not "unassign" functions. So if you create a function, it won't be deleted until the end of the script, even if you unset the variable containing its name.
If you need to change a part of a function everytime you run a loop, think of a way to make a more general function or try using eval :) (functions are made to be re-used. If you need to run your own piece of code once, eval is much better).
coleyeder at gmail dot com ¶
9 years ago
Default values works:
<?php
$f = create_function('$a,$b=3', 'var_dump($a, $b);');
$f(1);
// output:
// int(1)
// int(3)
?>
maxim at maxim dot cx ¶
22 years ago
for those who want to assign it's own name to a function consider this code:
<?php
$fname = 'hello';
$func = sprintf('
function %s($v="") {
Return "$v<BR>";
}
',
$fname
);
eval($func);
echo $fname('Please print it.... please....');
?>
what it does is,
: Creats a function as a string;
: Replaces the function name with $fname value;
: Converts the string into a REAL php code with eval()
: Calls the function using the variable function as declared before ($fname);
Simple, isn't it?
Can work well as an abstraction layer for portability and/or compatibility purposes
Maxim Maletsky
maxim@maxim.cx // PHPBeginner.com
mrben at free dot fr ¶
22 years ago
Here is another tricky but usefull techynote, good for adding "plugin" to a existing class :
<?php
class Hoge {
var $lamda;
var $text;
function set($lamda)
{
$this->lamda = $lamda;
}
function callLamda()
{
$func = $this->lamda;
return $func($this);
}
function get()
{
return $this->text;
}
}
$newfunc = create_function('&$class', 'echo $class->get();' );
$h = new Hoge;
$h->text = "Hi there !";
$h->set($newfunc);
$h->callLamda();
?>
