Learning Exercise
To share code between different Elixir modules within the same project, you need to reference the outside module by its full name. But what if that name is too long or confusing?
The special form alias allows you to shorten or change the name by which you reference an outside module. When used without any arguments, it trims down the module name to its last segment, e.g. MyApp.Logger.Settings becomes Settings. A custom name can be specified with the :as option.
Usually aliases are added at the beginning of the module definition.
defmodule Square do
alias Integer, as: I
def area(a), do: I.pow(a, 2)
end
The special form import allows you to use functions from an outside module without using the module's name.
Importing a whole outside module might create conflicts with existing local functions. To avoid this, two options are available: :except and :only. Both expect a keyword list, where the key is the function name, and the value is the function's arity.
Usually imports are added at the beginning of the module definition.
defmodule Square do
import Integer, only: [pow: 2]
def area(a), do: pow(a, 2)
end
That remote controlled car that you bought recently has turned into a whole new hobby. You have been organizing remote control car races.
You were almost finished writing a program that would allow to run race simulations when your cat jumped at your keyboard and deleted a few lines of code. Now your program doesn't compile anymore...
Race.__struct__/0 is undefined
Add an alias so that the module NeedForSpeed.Race can be referenced by the shorter name Race.
Car.__struct__/0 is undefined
Add an alias so that the module NeedForSpeed.RemoteControlCar can be referenced by the shorter name Car.
undefined function puts/1
The function puts/1 comes from the module IO. Import it to be able to use it without referencing the module.
undefined function default_color/0
The functions default_color/0, red/0, cyan/0, and green/0 all come from the module IO.ANSI. You're planning to add support for other car colors, so you want to import the whole module. Unfortunately, the function color/1 from the module IO.ANSI conflicts with one of your local functions. Import the whole IO.ANSI module except that one function.
Edit via GitHub
Sign up to Exercism to learn and master Elixir with 57 concepts, 158 exercises, and real human mentoring, all for free.