Term2::Model

Model contains the program's state as well as its core functions.

Any type that includes this module and implements the required methods can be used as a model. This mirrors Go's interface-based approach where any struct with the right methods implements Model.

class Counter
  include Term2::Model

  getter count : Int32 = 0

  def init : Term2::Cmd
    nil # no initial command
  end

  def update(msg : Term2::Msg) : {Term2::Model, Term2::Cmd}
    case msg
    when Term2::KeyMsg
      case msg.key.to_s
      when "q" then {self, Term2.quit}
      when "+" then {Counter.new(@count + 1), nil}
      else          {self, nil}
      end
    else
      {self, nil}
    end
  end

  def view : String
    "Count: #{@count}"
  end
end