PHP閉包定義與使用簡(jiǎn)單示例

?php
function getClosure($i)
{
  $i = $i.'-'.date('H:i:s');
  return function ($param) use ($i) {
    echo "--- param: $param ---\n";
    echo "--- i: $i ---\n";
  };
}
$c = getClosure(123);
$i = 456;
$c('test');
sleep(3);
$c2 = getClosure(123);
$c2('test');
$c('test');
/*
output:
--- param: test ---
--- i: 123-21:36:52 ---
--- param: test ---
--- i: 123-21:36:55 ---
--- param: test ---
--- i: 123-21:36:52 ---
*/

$message = 'hello';
$example = function() use ($message){
 var_dump($message);
};
echo $example();
//輸出hello
$message = 'world';
//輸出hello 因?yàn)槔^承變量的值的時(shí)候是函數(shù)定義的時(shí)候而不是 函數(shù)被調(diào)用的時(shí)候
echo $example();
//重置為hello
$message = 'hello';
//此處傳引用
$example = function() use($message){
 var_dump($message);
};
echo $example();
//輸出hello
$message = 'world';
echo $example();
//此處輸出world
//閉包函數(shù)也用于正常的傳值
$message = 'hello';
$example = function ($data) use ($message){
 return "{$data},{$message}";
};
echo $example('world');
//此處輸出world,hello