Add Abstract factory 🎉

.travis.yml

@@ -0,0 +1,7 @@
+language: go
+go:
+  - master
+env:
+  - GO111MODULE=on
+script:
+  - go test .

abstract_factory.go

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+package patterns
+
+import (
+	"fmt"
+)
+
+// Button interface
+type Button interface {
+	Paint()
+}
+
+// GUIFactory interface
+type GUIFactory interface {
+	CreateButton() Button
+}
+
+// ReactFactory struct
+type ReactFactory struct{}
+
+// CreateButton method on ReactFactory struct
+func (f *ReactFactory) CreateButton() Button {
+	return new(ReactButton)
+}
+
+// VueFactory struct
+type VueFactory struct{}
+
+// CreateButton method on VueFactory struct
+func (f *VueFactory) CreateButton() Button {
+	return new(VueButton)
+}
+
+// AngularFactory struct
+type AngularFactory struct{}
+
+// CreateButton method on AngularFactory struct
+func (f *AngularFactory) CreateButton() Button {
+	return new(AngularButton)
+}
+
+// ReactButton struct
+type ReactButton struct{}
+
+// Paint method on ReactButton struct
+func (b *ReactButton) Paint() {
+	fmt.Println("ReactButton")
+}
+
+// VueButton struct
+type VueButton struct{}
+
+// Paint method on VueButton struct
+func (b *VueButton) Paint() {
+	fmt.Println("VueButton")
+}
+
+// AngularButton struct
+type AngularButton struct{}
+
+// Paint method on AngularButton struct
+func (b *AngularButton) Paint() {
+	fmt.Println("AngularButton")
+}
+
+const (
+	// React denote
+	React = iota
+	// Vue denote
+	Vue
+	// Angular denote
+	Angular
+)
+
+// BuildFactory function return GUIFactory instance
+func BuildFactory(appearance int) GUIFactory {
+	switch appearance {
+	case React:
+		return new(ReactFactory)
+	case Vue:
+		return new(VueFactory)
+	case Angular:
+		return new(AngularFactory)
+	}
+	return nil
+}

abstract_factory_test.go

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+package patterns
+
+func ExampleBuildFactory() {
+	if factory := BuildFactory(React); factory != nil {
+		reactButton := factory.CreateButton()
+		reactButton.Paint()
+	}
+
+	if factory := BuildFactory(Vue); factory != nil {
+		vueButton := factory.CreateButton()
+		vueButton.Paint()
+	}
+
+	if factory := BuildFactory(Angular); factory != nil {
+		angularButton := factory.CreateButton()
+		angularButton.Paint()
+	}
+
+	// Output:
+	// ReactButton
+	// VueButton
+	// AngularButton
+}