php闭包中使用use声明变量的作用域实例分析

　　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：

　　 <?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）。

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　　希望本文所述对大家PHP程序设计有所帮助。