blocks|key|1589028|text|不，函数不是PHP中的第一类值，它们不能通过它们的名称文字传递(这正是您所要求的)。甚至匿名函数或通过create_function创建的函数也是通过对象或字符串引用传递的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1589029|您可以将函数的名称作为字符串传递，将对象方法的名称作为(object,+string)数组传递，或者将匿名函数作为对象传递。这些函数都不传递指针或引用，它们只是传递函数的名称。所有这些方法都称为callback伪类型：http://php.net/callback|1589030|entityMap|0|LINK|mutability|MUTABLE|url|http://php.net/callback^0|1F|F|0|R|G|2P|8|31|N|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@$9|X|A|Y|1|Z]]|E|$]]|$1|H|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]]]

No, functions are not first class values in PHP, they cannot be passed by their name literal (which is what you're asking for). Even anonymous functions or functions created via <code>create_function</code> are passed by an object or string reference.

You can pass a name of a function as string, the name of an object method as <code>(object, string)</code> array or an anonymous function as object. None of these pass pointers or references, they just pass on the name of the function. All of these methods are known as the <code>callback</code> pseudo-type: <a href="http://php.net/callback" rel="nofollow">http://php.net/callback</a>

blocks|key|1589032|text|你可以说|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1589033|$fun+=+'test';+
call($fun);+|code-block|syntax|javascript|1589034|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can say 

<pre><code>$fun = 'test'; 
call($fun); 
</code></pre>

blocks|key|1589036|text|使用call_user_func('test');而不是call(test);。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1589037|entityMap^0|2|N|S|B|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]|$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|M|8|@]|D|@]|E|$]]]|G|$]]

Instead of <code>call(test);</code>, use <code>call_user_func('test');</code>.

blocks|key|1589039|text|call_user_func()的问题在于，您传递的是被调用函数的返回值，而不是函数本身。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1589040|我以前也遇到过这个问题，下面是我想出的解决方案。|1589041|function+funcRef($func){
++return+create_function('',+"return+call_user_func_array('{$func}',+func_get_args());");
}

function+foo($a,+$b,+$c){
++++return+sprintf("A:%25s+B:%25s+C:%25s",+$a,+$b,+$c);
}

$b+=+funcRef("foo");

echo+$b("hello",+"world",+123);

//=>+A:hello+B:world+C:123|code-block|syntax|javascript|1589042|ideone.com+demo|1589043|entityMap|0|LINK|mutability|MUTABLE|url|http://ideone.com/vP6zkV^0|0|G|0|0|0|0|F|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|10|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|11|8|@]|D|@$9|12|A|13|1|14]]|E|$]]|$1|O|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]]]

The problem with <code>call_user_func()</code> is that you're passing the return value of the function called, not the function itself.

I've run into this problem before too and here's the solution I came up with.

<pre><code>function funcRef($func){
 return create_function('', "return call_user_func_array('{$func}', func_get_args());");
}

function foo($a, $b, $c){
 return sprintf("A:%s B:%s C:%s", $a, $b, $c);
}

$b = funcRef("foo");

echo $b("hello", "world", 123);

//=&gt; A:hello B:world C:123
</code></pre>

<a href="http://ideone.com/vP6zkV" rel="noreferrer">ideone.com demo</a>

blocks|key|1803586|text|在PHP+5.4.4+(没有测试过更低版本或其他版本)中，您可以完全按照您的建议执行操作。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1803587|以此为例：|1803588|function+test+($func)+{
++++$func('moo');
}

function+aFunctionToPass+($str)+{
++++echo+$str;
}

test('aFunctionToPass');|code-block|syntax|javascript|1803589|该脚本将回显"moo“，就好像您直接调用了"aFunctionToPass”一样。|1803590|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|O|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

In PHP 5.4.4 (haven't tested lower or other versions), you can do exactly as you suggested.

Take this as an example:

<pre><code>function test ($func) {
 $func('moo');
}

function aFunctionToPass ($str) {
 echo $str;
}

test('aFunctionToPass');
</code></pre>

The script will echo "moo" as if you called "aFunctionToPass" directly.

blocks|key|1803592|text|function+func1(){
++++echo+'echo1+';
++++return+'return1';
}

function+func2($func){
++++echo+'echo2+'+.+$func();
}

func2('func1');|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1803593|结果：|unstyled|1803594|echo1+echo2+return1|1803595|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>function func1(){
 echo 'echo1 ';
 return 'return1';
}

function func2($func){
 echo 'echo2 ' . $func();
}

func2('func1');
</code></pre>

Result:

<pre><code>echo1 echo2 return1
</code></pre>

blocks|key|1803597|text|您可以通过在声明函数时将函数分配给局部变量来创建引用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1803598|$test+=+function()+{
++++echo+"hello+world!";
};

function+call($func){
++++$func();
}

call($test);|code-block|syntax|javascript|1803599|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You can create a reference by assigning the function to a local variable when you declare it:

<pre><code>$test = function() {
 echo "hello world!";
};

function call($func){
 $func();
}

call($test);
</code></pre>

blocks|key|1589062|text|从PHP8.1开始，您可以使用First-class+callables|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1589063|call(test(...));|code-block|syntax|javascript|1589064|您甚至可以使用方法：|1589065|call($obj->test(...));|1589066|就这么简单。|1589067|entityMap|0|LINK|mutability|MUTABLE|url|https://wiki.php.net/rfc/first_class_callable_syntax^0|F|L|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@$A|X|B|Y|1|Z]]|C|$]]|$1|D|3|E|5|F|7|10|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|11|8|@]|9|@]|C|$]]|$1|K|3|L|5|F|7|12|8|@]|9|@]|C|$G|H]]|$1|M|3|N|5|6|7|13|8|@]|9|@]|C|$]]|$1|O|3|-4|5|6|7|14|8|@]|9|@]|C|$]]]|P|$Q|$5|R|S|T|C|$U|V]]]]

As of PHP 8.1, you can use <a href="https://wiki.php.net/rfc/first_class_callable_syntax" rel="nofollow noreferrer">First-class callables</a>:
<pre><code>call(test(...));
</code></pre>
You can even use methods:
<pre><code>call($obj-&gt;test(...));
</code></pre>
As simple as it is.

Is it possible to pass functions by reference?

Something like this:

<pre><code>function call($func){
 $func();
}

function test(){
 echo "hello world!";
}

call(test);
</code></pre>

I know that you could do <code>'test'</code>, but I don't really want that, as I need to pass the function by reference.

Is the only way to do so via anonymous functions?

Clarification: If you recall from C++, you could pass a function via pointers:

<pre><code>void call(void (*func)(void)){
 func();
}
</code></pre>

Or in Python:

<pre><code>def call(func):
 func()
</code></pre>

That's what i'm trying to accomplish.

Pass a function by reference in PHP

Python

可以通过引用传递函数吗？如下所示：function call($func){    $func();}function test(){    echo "hello world!";}call(test);我知道你可以做'test'，但我真的不想那样做，因为我需要通过引用传递函数。只有通过匿名函数才能做到这一点吗？说明...

问在PHP中通过引用传递函数
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