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(lái)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(lái)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(lái)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(lèi)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(lèi)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）。
希望本文所述對(duì)大家PHP程序設(shè)計(jì)有所幫助。
