php闭包中使用use声明变量的作用域实例分析
author:一佰互联 2019-04-25   click:125

本文实例讲述了php闭包中使用use声明变量的作用域。分享给大家供大家参考,具体如下:

<?phpfunction getClosure($i){    $i = $i."-".date("H:i:s");    return function ($param) use ($i) {        echo "--- param: $param ---";        echo "--- i: $i ---";    };}$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 pointsBranch analysis from position: 0Jump found. Position 1 = -2filename:       /tmp/testclosure.phpfunction name:  (null)number of ops:  20compiled vars:  !0 = $c, !1 = $i, !2 = $c2line     #* 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                                                   1Function %00%7Bclosure%7D%2Ftmp%2Ftestclosure.php0x7fb0115f505:Finding entry pointsBranch analysis from position: 0Jump found. Position 1 = -2filename:       /tmp/testclosure.phpfunction name:  {closure}number of ops:  12compiled vars:  !0 = $param, !1 = $iline     #* 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                                                   nullEnd of function %00%7Bclosure%7D%2Ftmp%2Ftestclosure.php0x7fb0115f505Function getclosure:Finding entry pointsBranch analysis from position: 0Jump found. Position 1 = -2filename:       /tmp/testclosure.phpfunction name:  getClosurenumber of ops:  9compiled vars:  !0 = $iline     #* 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                                                   nullEnd 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)。

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