php闭包中use(变量)的作用域

<?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 ---
*/

如上，闭包中使用use声明的变量来自于生成闭包实例时所在作用域内的同名变量，而不是来自于运行闭包时所在作用域内的同名变量。而闭包的函数参数则是和正常的函数参数一样来自于运行时所在作用域内的同名变量。

以下为opcode：

Finding entry points
Branch analysis from position: 0
Jump found. Position 1 = -2
filename: /tmp/testclosure.php
function name: (null)
number of ops: 20
compiled vars: !0 = $c, !1 = $i, !2 = $c2
line     #* E I O op                           fetch          ext return operands
-------------------------------------------------------------------------------------
   2     0  E > NOP
  11     1        SEND_VAL                                                 123
         2        DO_FCALL                                      1  $0 'getclosure'
         3        ASSIGN !0, $0
  12     4        ASSIGN !1, 456
  13     5        INIT_FCALL_BY_NAME !0
         6        SEND_VAL 'test'
         7        DO_FCALL_BY_NAME                              1
  14     8        SEND_VAL                                                 3
         9        DO_FCALL                                      1 'sleep'
  15    10        SEND_VAL                                                 123
        11        DO_FCALL                                      1  $5 'getclosure'
        12        ASSIGN !2, $5
  16    13        INIT_FCALL_BY_NAME !2
        14        SEND_VAL 'test'
        15        DO_FCALL_BY_NAME                              1
  17    16        INIT_FCALL_BY_NAME !0
        17        SEND_VAL 'test'
        18        DO_FCALL_BY_NAME                              1
  29    19 > RETURN 1

Function %00%7Bclosure%7D%2Ftmp%2Ftestclosure.php0x7fb0115f505:
Finding entry points
Branch analysis from position: 0
Jump found. Position 1 = -2
filename: /tmp/testclosure.php
function name: {closure}
number of ops: 12
compiled vars: !0 = $param, !1 = $i
line     #* E I O op                           fetch          ext return operands
-------------------------------------------------------------------------------------
   5     0  E > RECV !0
         1        FETCH_R                      static              $0 'i'
         2        ASSIGN !1, $0
   6     3        ADD_STRING ~2 '---+param%3A+'
         4        ADD_VAR ~2 ~2, !0
         5        ADD_STRING ~2 ~2, '+---%0A'
         6        ECHO ~2
   7     7        ADD_STRING ~3 '---+i%3A+'
         8        ADD_VAR ~3 ~3, !1
         9        ADD_STRING ~3 ~3, '+---%0A'
        10        ECHO ~3
   8    11 > RETURN null

End of function %00%7Bclosure%7D%2Ftmp%2Ftestclosure.php0x7fb0115f505

Function getclosure:
Finding entry points
Branch analysis from position: 0
Jump found. Position 1 = -2
filename: /tmp/testclosure.php
function name: getClosure
number of ops: 9
compiled vars: !0 = $i
line     #* E I O op                           fetch          ext return operands
-------------------------------------------------------------------------------------
   2     0  E > RECV !0
   4     1        CONCAT ~0 !0, '-'
         2        SEND_VAL 'H%3Ai%3As'
         3        DO_FCALL                                      1  $1 'date'
         4        CONCAT ~2 ~0, $1
         5        ASSIGN !0, ~2
   5     6        DECLARE_LAMBDA_FUNCTION '%00%7Bclosure%7D%2Ftmp%2Ftestclosure.php0x7fb0115f5051'
   8     7 > RETURN ~4
   9     8* > RETURN null

End of function getclosure

如上，闭包函数的op_array（相当于类定义）在编译期完成，但在运行期生成闭包实例（相当于类实例）时会为不同实例绑定不同的use静态变量（在DECLARE_LAMBDA_FUNCTION中完成）。