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php閉包中使用use聲明變量的作用域?qū)嵗治?/h1>
 更新時(shí)間：2018年08月09日 11:55:32   作者：flynetcn  
這篇文章主要介紹了php閉包中使用use聲明變量的作用域,結(jié)合實(shí)例形式分析了閉包中use聲明變量作用域的相關(guān)原理與分析,需要的朋友可以參考下

本文實(shí)例講述了php閉包中使用use聲明變量的作用域。分享給大家供大家參考，具體如下：

<?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，閉包中使用use聲明的變量來自于生成閉包實(shí)例時(shí)所在作用域內(nèi)的同名變量，而不是來自于運(yùn)行閉包時(shí)所在作用域內(nèi)的同名變量。

而閉包的函數(shù)參數(shù)則是和正常的函數(shù)參數(shù)一樣來自于運(yùn)行時(shí)所在作用域內(nèi)的同名變量。

以下為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，閉包函數(shù)的op_array（相當(dāng)于類定義）在編譯期完成，但在運(yùn)行期生成閉包實(shí)例（相當(dāng)于類實(shí)例）時(shí)會(huì)為不同實(shí)例綁定不同的use靜態(tài)變量（在DECLARE_LAMBDA_FUNCTION中完成）。

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