Pokemon Protocols

Mix.install([
  {:jason, "~> 1.4"},
  {:kino, "~> 0.9", override: true},
  {:youtube, github: "brooklinjazz/youtube"},
  {:hidden_cell, github: "brooklinjazz/hidden_cell"}
])

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Overview

Pokemon are creatures which have the ability to evolve into more powerful versions of themselves.

For example, Charmander evolves into Charmeleon, and Charmeleon evolves into Charizard.

flowchart LR
  c1[Charmander]
  c2[Charmeleon]
  c3[Charizard]
  c1 --> c2 --> c3

In this exercise, you will create an Evolvable protocol which returns the evolved version of a Pokemon.

Evolvable.evolve(%Charmander{})
%Charmeleon{hp: 58, attack: 64: defense: 58}

Pokemon Structs

In the Elixir cell below, Using the stats from Pokemon DB, you’re going to create a struct that represents each of the following Pokemon.

• Charmander
• Charmeleon
• Charizard

Each struct should include the following.

• :hp
• :attack
• :defense

You can use the base values as defaults from Pokemon DB as shown in the following diagram.

classDiagram
  class Charmander {
    hp: 39
    attack: 52
    defense: 43
  }

  class Charmeleon {
    hp: 58
    attack: 64
    defense: 58
  }

  class Charizard {
    hp: 78
    attack: 84
    defense: 78
  }

Example Solution

defmodule Charmander do
  defstruct hp: 39, attack: 52, defense: 43
end

defmodule Charmeleon do
  defstruct hp: 58, attack: 64, defense: 58
end

defmodule Charizard do
  defstruct hp: 78, attack: 84, defense: 78
end

defmodule Charmander do
end

defmodule Charmeleon do
end

defmodule Charizard do
end

Evolvable Protocol

In the Elixir cell below, create an Evolvable protocol with an evolve/1 function.

A Charmander struct should return a new Charmeleon struct.

Evolvable.evolve(%Charmander{})
%Charmeleon{hp: 58, attack: 64: defense: 58}

A Charmeleon struct should return a new Charizard struct.

Evolvable.evolve(%Charmeleon{})
%Charizard{hp: 78, attack: 84: defense: 78}

Example Solution

defprotocol Evolvable do
  def evolve(pokemon)
end

defimpl Evolvable, for: Charmander do
  def evolve(_charmander), do: %Charmeleon{}
end

defimpl Evolvable, for: Charmeleon do
  def evolve(_charmeleon), do: %Charizard{}
end

defprotocol Evolvable do
end

Mark As Completed

file_name = Path.basename(Regex.replace(~r/#.+/, __ENV__.file, ""), ".livemd")

progress_path = __DIR__ <> "/../progress.json"
existing_progress = File.read!(progress_path) |> Jason.decode!()

default = Map.get(existing_progress, file_name, false)

form =
  Kino.Control.form(
    [
      completed: input = Kino.Input.checkbox("Mark As Completed", default: default)
    ],
    report_changes: true
  )

Task.async(fn ->
  for %{data: %{completed: completed}} <- Kino.Control.stream(form) do
    File.write!(progress_path, Jason.encode!(Map.put(existing_progress, file_name, completed)))
  end
end)

form

Commit Your Progress

Run the following in your command line from the curriculum folder to track and save your progress in a Git commit. Ensure that you do not already have undesired or unrelated changes by running git status or by checking the source control tab in Visual Studio Code.

$ git checkout solutions
$ git checkout -b pokemon-protocols-exercise
$ git add .
$ git commit -m "finish pokemon protocols exercise"
$ git push origin pokemon-protocols-exercise

Create a pull request from your pokemon-protocols-exercise branch to your solutions branch. Please do not create a pull request to the DockYard Academy repository as this will spam our PR tracker.

DockYard Academy Students Only:

Notify your instructor by including @BrooklinJazz in your PR description to get feedback. You (or your instructor) may merge your PR into your solutions branch after review.

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