PHP call_user_func 与仅调用函数
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PHP call_user_func vs. just calling function
提问by jay
I'm sure there's a very easy explanation for this. What is the difference between this:
我相信对此有一个非常简单的解释。这有什么区别：
function barber($type){
echo "You wanted a $type haircut, no problem\n";
}
call_user_func('barber', "mushroom");
call_user_func('barber', "shave");
... and this (and what are the benefits?):
......还有这个（以及有什么好处？）：
function barber($type){
echo "You wanted a $type haircut, no problem\n";
}
barber('mushroom');
barber('shave');
采纳答案by Kai
Always use the actual function name when you know it.
当您知道时，请始终使用实际的函数名称。
call_user_funcis for calling functions whose name you don't know ahead of time but it is much less efficient since the program has to lookup the function at runtime.
call_user_func用于调用您事先不知道名称的函数，但效率低得多，因为程序必须在运行时查找函数。
回答by Lucas Oman
Although you can call variable function names this way:
虽然您可以通过这种方式调用变量函数名：
function printIt($str) { print($str); }
$funcname = 'printIt';
$funcname('Hello world!');
there are cases where you don't know how many arguments you're passing. Consider the following:
在某些情况下，您不知道传递了多少参数。考虑以下：
function someFunc() {
$args = func_get_args();
// do something
}
call_user_func_array('someFunc',array('one','two','three'));
It's also handy for calling static and object methods, respectively:
分别调用静态和对象方法也很方便：
call_user_func(array('someClass','someFunc'),$arg);
call_user_func(array($myObj,'someFunc'),$arg);
回答by Brian Schroth
the call_user_funcoption is there so you can do things like:
该call_user_func选项在那里，因此您可以执行以下操作：
$dynamicFunctionName = "barber";
call_user_func($dynamicFunctionName, 'mushroom');
where the dynamicFunctionNamestring could be more exciting and generated at run-time. You shouldn't use call_user_func unless you have to, because it is slower.
其中dynamicFunctionName字符串可以更加精彩，并在运行时产生的。你不应该使用 call_user_func 除非你必须，因为它更慢。
回答by pivotal
I imagine it is useful for calling a function that you don't know the name of in advance... Something like:
我想这对于调用一个你事先不知道名称的函数很有用......像：
switch($value):
{
case 7:
$func = 'run';
break;
default:
$func = 'stop';
break;
}
call_user_func($func, 'stuff');
回答by uingtea
There is no benefits calling the function like that because I think it mainly used to call "user" function (like plugin) because editing core file is not good option. here are dirty example used by Wordpress
这样调用函数没有任何好处，因为我认为它主要用于调用“用户”函数（如插件），因为编辑核心文件不是一个好的选择。这是 Wordpress 使用的脏示例
<?php
/*
* my_plugin.php
*/
function myLocation($content){
return str_replace('@', 'world', $content);
}
function myName($content){
return $content."Tasikmalaya";
}
add_filter('the_content', 'myLocation');
add_filter('the_content', 'myName');
?>
...
...
<?php
/*
* core.php
* read only
*/
$content = "hello @ my name is ";
$listFunc = array();
// store user function to array (in my_plugin.php)
function add_filter($fName, $funct)
{
$listFunc[$fName]= $funct;
}
// execute list user defined function
function apply_filter($funct, $content)
{
global $listFunc;
if(isset($listFunc))
{
foreach($listFunc as $key => $value)
{
if($key == $funct)
{
$content = call_user_func($listFunc[$key], $content);
}
}
}
return $content;
}
function the_content()
{
$content = apply_filter('the_content', $content);
echo $content;
}
?>
....
....
<?php
require_once("core.php");
require_once("my_plugin.php");
the_content(); // hello world my name is Tasikmalaya
?>
output
输出
hello world my name is Tasikmalaya
回答by mils
With PHP 7 you can use the nicer variable-function syntax everywhere. It works with static/instance functions, and it can take an array of parameters. More info at https://trowski.com/2015/06/20/php-callable-paradox
使用 PHP 7，您可以在任何地方使用更好的变量函数语法。它与静态/实例函数一起工作，并且可以接受一组参数。更多信息请访问https://trowski.com/2015/06/20/php-callable-paradox
$ret = $callable(...$params);
回答by SilentGhost
in your first example you're using function name which is a string. it might come from outside or be determined on the fly. that is, you don't know what function will need to be run at the moment of the code creation.
在您的第一个示例中，您使用的函数名称是一个字符串。它可能来自外部或即时确定。也就是说，您不知道在创建代码时需要运行什么函数。
回答by ThomasRedstone
When using namespaces, call_user_func() is the only way to run a function you don't know the name of beforehand, for example:
使用命名空间时， call_user_func() 是运行事先不知道名称的函数的唯一方法，例如：
$function = '\Utilities\SearchTools::getCurrency';
call_user_func($function,'USA');
If all your functions were in the same namespace, then it wouldn't be such an issue, as you could use something like this:
如果你所有的函数都在同一个命名空间中，那么就不会出现这样的问题，因为你可以使用这样的东西：
$function = 'getCurrency';
$function('USA');
Edit: Following @Jannis saying that I'm wrong I did a little more testing, and wasn't having much luck:
编辑：在@Jannis 说我错了之后，我做了更多测试，但运气不佳：
<?php
namespace Foo {
class Bar {
public static function getBar() {
return 'Bar';
}
}
echo "<h1>Bar: ".\Foo\Bar::getBar()."</h1>";
// outputs 'Bar: Bar'
$function = '\Foo\Bar::getBar';
echo "<h1>Bar: ".$function()."</h1>";
// outputs 'Fatal error: Call to undefined function \Foo\Bar::getBar()'
$function = '\Foo\Bar\getBar';
echo "<h1>Bar: ".$function()."</h1>";
// outputs 'Fatal error: Call to undefined function \foo\Bar\getBar()'
}
You can see the output results here: https://3v4l.org/iBERhit seems the second method works for PHP 7 onwards, but not PHP 5.6.
您可以在此处查看输出结果：https: //3v4l.org/iBERh似乎第二种方法适用于 PHP 7 以上，但不适用于 PHP 5.6。
