new feature: versioned controllers

Former-commit-id: c797e23c78b1e74bbe9ba56673f3a98f17f5e2f7

_examples/mvc/versioned-controller/main.go

@@ -0,0 +1,52 @@
+package main
+
+import (
+	"github.com/kataras/iris/v12"
+	"github.com/kataras/iris/v12/mvc"
+)
+
+func main() {
+	app := newApp()
+
+	// See main_test.go for request examples.
+	app.Listen(":8080")
+}
+
+func newApp() *iris.Application {
+	app := iris.New()
+
+	dataRouter := app.Party("/data")
+	{
+		m := mvc.New(dataRouter)
+		m.Handle(new(v1Controller), mvc.Version("1"))       // 1 or 1.0, 1.0.0 ...
+		m.Handle(new(v2Controller), mvc.Version("2.3"))     // 2.3 or 2.3.0
+		m.Handle(new(v3Controller), mvc.Version(">=3, <4")) // 3, 3.x, 3.x.x ...
+		m.Handle(new(noVersionController))
+	}
+
+	return app
+}
+
+type v1Controller struct{}
+
+func (c *v1Controller) Get() string {
+	return "data (v1.x)"
+}
+
+type v2Controller struct{}
+
+func (c *v2Controller) Get() string {
+	return "data (v2.x)"
+}
+
+type v3Controller struct{}
+
+func (c *v3Controller) Get() string {
+	return "data (v3.x)"
+}
+
+type noVersionController struct{}
+
+func (c *noVersionController) Get() string {
+	return "data"
+}