如何在php闭包中使用use声明变量的作用域

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具体如下：

<?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

php有什么特点

1、执行速度快。2、具有很好的开放性和可扩展性。3、PHP支持多种主流与非主流的数据库。4、面向对象编程：PHP提供了类和对象。5、版本更新速度快。6、具有丰富的功能。7、可伸缩性。8、功能全面，包括图形处理、编码与解码、压缩文件处理、xml解析等。

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