PHP lambda函数和作用域 [英] PHP lambda functions and scope

问题描述

以下函数接受一个数组，并检查其键和值是否与指定的数据类型匹配.

The below function takes an array and checks to see if its keys and values match the specified datatypes.

我似乎以前使用的内部lambda函数有一些问题.我正在运行PHP v5.3.6.他们上一次在v5.3.4下工作.他们抱怨未传递的变量不在范围内.如果我将该变量重新声明为global，则错误消失了，但是变量为空.

I seem to be having some problems with the internal lambda functions that were previously working. I'm running PHP v5.3.6. They last worked under v5.3.4. They are complaining that the non-passed variable is not in scope. If I restate that variable as global then the error goes away, but the variable is empty.

/**
 * @param array $arr, array to be tested
 * @param mixed $keytype
 * @param mixed $valuetype
 * @example acceptable_arr( array(1,2,3,4,'string'), NULL, 'integer') returns false
 * @example acceptable_arr( array('thing'=>1,'other'=>2), 'string', 'integer') returns true
 * @example acceptable_arr( array('thing'=>1,'other'=>2), 'string', 'array') returns false
 */
function acceptable_arr(array $arr,$keytype=NULL,$valuetype=NULL){
     print_r(func_get_args()); //debugging

    $valfail=true; $keyfail=true;
    if($keytype==NULL && $valuetype==NULL) return true;

    if(!is_null($keytype)) {
        $keytest='is_'.$keytype;
        if(function_exists($keytest)){
            $fn_kfail=function($v){return call_user_func($keytest,$v);}; //PROBLEM LINE 218
            $keyfail=(!is_null($keytype)) ? array_sum(array_map($fn_kfail,array_keys($arr))) : false;
        }
    }

    if(!is_null($valuetype)) {
        $valtest='is_'.$valuetype;
        if(function_exists($valtest)){
            $fn_vfail=function($v){return call_user_func($valtest,$v);}; //PROBLEM LINE 226
            $valfail=(!is_null($valuetype)) ? array_sum(array_map($fn_vfail,$arr)) : false;
        }
    }

    return  !($valfail && $keyfail);
}

运行上面的函数将输出以下内容:

Running the above function outputs this:

Array
(
    [0] => Array
        (
            [0] => main
        )

    [1] => integer
    [2] => string
)

注意:未定义变量:keytest输入 218行

Notice: Undefined variable: keytest in line 218

警告:call_user_func()预期 参数1是有效的回调，否 第218行中给出的数组或字符串

Warning: call_user_func() expects parameter 1 to be a valid callback, no array or string given in line 218

注意:未定义的变量:valtest in 226行

Notice: Undefined variable: valtest in line 226

警告:call_user_func()预期 参数1是有效的回调，否 在第226行中给出的数组或字符串

Warning: call_user_func() expects parameter 1 to be a valid callback, no array or string given in line 226

$ keytest和$ valtest值去哪里了?为什么即使我这样声明它们都是全局的，它们在lambda函数中也为空?

Where did the $keytest and $valtest values go? Why are they empty inside the lambda functions even if I declare them global like this?

$fn_vfail=function($v){ 
  global $valtest; 
  return call_user_func($valtest,$v);
};

推荐答案

function($v) use ($valtest) { ...

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