dsl.go

package main


type Task struct {
	action     func()
	depends_on []*Task
}

func (t *Task) Run() {
	if t.depends_on != nil {
		for _, st := range t.depends_on {
			st.action()
		}
	}
	t.action()
}

type ActionT struct {
	action func()
}

type DependencyT struct {
	d []*Task
}

func Action(fn func()) ActionT { return ActionT{fn} }

func DependsOn(t ...*Task) DependencyT { return DependencyT{t} }

func task(a ...interface{}) *Task {
	result := &Task{}
	for _, x := range a {
		switch v := x.(type) {
		case ActionT:
			result.action = v.action
		case DependencyT:
			result.depends_on = v.d
		}
	}
	return result
}

//------------------------------

func main() {
	var hello = task(
		Action(func() { println("Hello") }))
	var world = task(
		Action(func() { println("World!") }),
		DependsOn(hello))

	var bye = task(
		Action(func() { println("Bye!") }),
		DependsOn(hello, world))
	bye.Run()
}