Groovy里面闭包中变量符号的查找与变量定义的限制

 1 class a {
 2     def v1 = "v1 in a"
 3     static def v2 = "v2 in a"
 4     def v4 = "v4 in a"
 5     def v5 = "v5 in a"
 6     def va = "va in a"
 7     def b() {
 8         def v1 = "v1 in a.b()"
 9         def v2 = "v2 in a.b()"
10         def v4 = "v4 in a.b()"
11         def g = {
12             def v0 = "v0 in closure g"
13             def h = {
14                 //function b里面已经定义v4 = "v4 in a.b()"所以下面这行
15                 //报错:The current scope already contains a variable of the name v4
16                 //def v4 = "v4 in closure h"
17             }
18         }
19         def c = {
20             //下面的这行代码报错:The current scope already contains a variable of the name v1
21             //def v1 = "v1 in closure c"
22             println v1
23             println owner
24             println this
25             //下面这行定义v5变量正常,输出的结果也是:v5 in closure c
26             def v5 = "v5 in closure c"
27             println  v5//v4
28             println va
29         }
30         println "***" + c.toString() + "***"
31         c()
32         
33        return "b func"
34     }
35     
36     def d = {
37         println v1;
38         println v2;
39         println v4;
40         def v5 = "v5 in closure d"
41         println v5
42     }
43     
44     def e = {
45         def v1 = "v1 in closure e"
46         def f = {
47             //下面这行代码报错:The current scope already contains a variable of the name v1
48             //def v1 = "v1 in closure f"
49             println v1
50             
51             //下面这行就没错,因为闭包e的v2是在后面定义的
52             def v2 = "v2 in closure f"
53     
54             //下面这行报错,v3在f里面不可见
55             //println v3
56             
57             def vf = "vf in closure f"
58         }
59         f()
60         def v2 = "v2 in closure e"
61         def v3 = "v3 in closure e"
62         
63         //在闭包e里面vf不可见
64         //println vf
65     }
66 }
67 def test(x) {
68     println "func test start --- x:" + x
69     def v1 = 1000
70     def v2 = 2000
71     def v3 = 3000
72     
73     x()
74     println "func test--- end:"
75 }
76 test(new a().d)
77 println "--------------"
78 //println new a().v4
79 println new a().b()
80 new a().e()
81 
82 
83 /*
84 通过上面的测试代码可以看出:
85 1.在闭包a里面定义的闭包b,那么b中定义的变量不能和和闭包a里面定义的变量名字相同.
86 2.在函数a里面定义的闭包b,那么b中定义的变量不能和和函数a里面定义的变量名字相同.
87 3.由此也可以推导出:在函数a里面定义闭包b,在闭包b里面定义闭包c,那么c中定义
88 的变量也不能和函数a中定义的变量名字相同,对于任意多层闭包嵌套也是如此
89 在闭包里面的符号查找方面:
90     首先在闭包里面查找,如果闭包里面没有定义,则有两种情况(假设delegate策略是Closure.OWNER_FIRST,其它策略是一样的):
91         1.如果这个闭包的外层是函数,则现在函数里面查找,如果函数里面也没有定义,则进入delegate策略即在owner里面查找,
92         如果owner里面没有,则在delegate里面查找,ruguo delegate里面没有就报错
93         2.如果这个闭包没外层不是函数,则直接进入delegate策略即在owner里面查找,如果owner里面没有,则在delegate里面查找
94         如果delegate里面没有就报错.
95 
96 */