added basic interface example (02a2872d) · Commits · bsmrgo / playground

interfaces/interfaces.go

0 → 100644

+70 −0

Original line number	Diff line number	Diff line
		package interfaces

		// S1 is an example structure.
		type S1 struct {
		v1 int
		}

		// S2 is an example structure.
		type S2 struct {
		v2 int
		}

		// S3 is an example structure.
		type S3 struct {
		v3 int
		}

		// NewS1 creates a new instance.
		func NewS1(v int) *S1 {
		return &S1{v1: v}
		}

		// Value implements the Valuer interface.
		func (s *S1) Value() int {
		return s.v1
		}

		// SetValue implements the Valuer interface.
		func (s *S1) SetValue(vn int) (vo int) {
		vo, s.v1 = s.v1, vn
		return
		}

		// NewS2 creates a new instance.
		func NewS2(v int) *S2 {
		return &S2{v2: v}
		}

		// Value implements the Valuer interface.
		func (s *S2) Value() int {
		return s.v2
		}

		// SetValue implements the Valuer interface.
		func (s *S2) SetValue(vn int) (vo int) {
		vo, s.v2 = s.v2, vn
		return
		}

		// NewS3 creates a new instance.
		func NewS3(v int) *S3 {
		return &S3{v3: v}
		}

		// Value implements the Valuer interface.
		func (s *S3) Value() int {
		return s.v3
		}

		// SetValue implements the Valuer interface.
		func (s *S3) SetValue(vn int) (vo int) {
		vo, s.v3 = s.v3, vn
		return
		}

		// Valuer provides accessor functions.
		type Valuer interface {
		Value() int // get current value
		SetValue(int) int // set new value, return old value
		}

0 → 100644

+25 −0

Original line number	Diff line number	Diff line
		package interfaces

		import "testing"

		func TestInterfacesAssignment(t *testing.T) {
		vn := 42
		for _, v := range []struct {
		s Valuer
		r int
		}{
		{NewS1(1), 1},
		{NewS2(2), 2},
		{NewS3(3), 3},
		} {
		if r := v.s.Value(); r != v.r {
		t.Logf("%v.Value() is %d, expected %d", v.s, r, v.r)
		}
		if ov := v.s.SetValue(vn); ov != v.r {
		t.Logf("%v.Value() is %d, expected %d", v.s, ov, v.r)
		}
		if r := v.s.Value(); r != vn {
		t.Logf("%v.Value() is %d, expected %d", v.s, r, vn)
		}
		}
		}