Now that you know the theoretical basics, let's look at these facilities and how they are used in our program. Let's open Lesson 2/3-project in our IDE and extend our chatbot, which was developed in the previous chapter.

Decoupling Logic and Environment

To do this, we must decouple the environment and logic, and integrate only one in the main method.

Let's open the EffectsProvider class:

trait EffectsProvider extends TimeProvider {

 def input: UserInput

 def output: UserOutput

}

object DefaultEffects extends EffectsProvider
{
 override def input: UserInput = ConsoleInput

 override def output: UserOutput = ConsoleOutput

 override def currentTime(): LocalTime = LocalTime.now()

 override def currentDate(): LocalDate = LocalDate.now()
}

Here, we encapsulate all of the effects into our traits, which can have different implementations.

For example, let's look at UserOutput:

For full code, refer to Code Snippets/Lesson 2.scala file.

trait UserOutput {

 def write(message: String): Unit

 def writeln(message: String): Unit = {
  write(message)
  write("\n")
 }

}


object ConsoleOutput extends UserOutput
{

 def write(message: String): Unit = {
  Console.print(message)
 }
}

Here, we can see the trait and object, which implement the current trait. This way, when we need to accept commands that are not from standard input, but from the chatbot API or from Twitter, we only need to change the implementation of the UserOutput/ ConsoleOutput interfaces.

It's now time to implement ConsoleOutput and DefaultTimeProvider.

Replace ??? in main with the appropriative constructor.

These steps for implementing ConsoleOutput and DefaultTimeProvider are as follows: