本文實例講述了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：
02 | function getClosure($i) |
04 | $i = $i.'-'.date('H:i:s'); |
05 | return function ($param) use ($i) { |
06 | echo "--- param: $param ---\n"; |
07 | echo "--- i: $i ---\n"; |
如上，閉包中使用use聲明的變量來自于生成閉包實例時所在作用域內的同名變量，而不是來自于運行閉包時所在作用域內的同名變量。
而閉包的函數參數則是和正常的函數參數一樣來自于運行時所在作用域內的同名變量。
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，閉包函數的op_array（相當于類定義）在編譯期完成，但在運行期生成閉包實例（相當于類實例）時會為不同實例綁定不同的use靜態變量（在DECLARE_LAMBDA_FUNCTION中完成）。
希望本文所述對大家PHP程序設計有所幫助。
