1 package singlefile
2
3 import "math"
4
5 type Shape interface {
6 Area() float64
7 isShape()
8 }
9
10 type ShapeUnion interface {
11 Area() float64
12 isShapeUnion()
13 }
14
15 type Circle struct {
16 Radius float64
17 Coordinates
18 }
19
20 func (c *Circle) Area() float64 {
21 return c.Radius * math.Pi * math.Pi
22 }
23
24 func (c *Circle) isShapeUnion() {}
25 func (c *Circle) isShape() {}
26
27 type Rectangle struct {
28 Length, Width float64
29 Coordinates
30 }
31
32 func (r *Rectangle) Area() float64 {
33 return r.Length * r.Width
34 }
35 func (r *Rectangle) isShapeUnion() {}
36 func (r *Rectangle) isShape() {}
37
38 type Node interface {
39 Child() (Node, error)
40 }
41
42 type ConcreteNodeA struct {
43 ID string
44 Name string
45 child Node
46 }
47
48 func (n *ConcreteNodeA) Child() (Node, error) {
49 return n.child, nil
50 }
51
52
53 type ConcreteNodeInterface interface {
54 Node
55 ID() string
56 }
57
58 type ConcreteNodeInterfaceImplementor struct{}
59
60 func (c ConcreteNodeInterfaceImplementor) ID() string {
61 return "CNII"
62 }
63
64 func (c ConcreteNodeInterfaceImplementor) Child() (Node, error) {
65 return &ConcreteNodeA{
66 ID: "Child",
67 Name: "child",
68 }, nil
69 }
70
71 type BackedByInterface interface {
72 ThisShouldBind() string
73 ThisShouldBindWithError() (string, error)
74 }
75
76 type BackedByInterfaceImpl struct {
77 Value string
78 Error error
79 }
80
81 func (b *BackedByInterfaceImpl) ThisShouldBind() string {
82 return b.Value
83 }
84
85 func (b *BackedByInterfaceImpl) ThisShouldBindWithError() (string, error) {
86 return b.Value, b.Error
87 }
88
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