00eb17014a
While doing this, I also discovered that there is also a reference to lists in numbers, but that might a bit easier for someone to grasp, given the hint that the koan gives, and the output they see when they run it.
68 lines
1.7 KiB
Elixir
68 lines
1.7 KiB
Elixir
defmodule Structs do
|
|
use Koans
|
|
|
|
@intro "Structs"
|
|
|
|
defmodule Person do
|
|
defstruct [:name, :age]
|
|
end
|
|
|
|
koan "Structs are defined and named after a module" do
|
|
person = %Person{}
|
|
assert person == ___
|
|
end
|
|
|
|
koan "Unless previously defined, fields begin as nil" do
|
|
nobody = %Person{}
|
|
assert nobody.age == ___
|
|
end
|
|
|
|
koan "You can pass initial values to structs" do
|
|
joe = %Person{name: "Joe", age: 23}
|
|
assert joe.name == ___
|
|
end
|
|
|
|
koan "Update fields with the cons '|' operator" do
|
|
joe = %Person{name: "Joe", age: 23}
|
|
older = %{joe | age: joe.age + 10}
|
|
assert older.age == ___
|
|
end
|
|
|
|
defmodule Plane do
|
|
defstruct passengers: 0, maker: :boeing
|
|
end
|
|
|
|
def plane?(%Plane{}), do: true
|
|
def plane?(_), do: false
|
|
|
|
koan "Or onto the type of the struct itself" do
|
|
assert plane?(%Plane{passengers: 417, maker: :boeing}) == ___
|
|
assert plane?(%Person{}) == ___
|
|
end
|
|
|
|
koan "Struct can be treated like maps" do
|
|
silvia = %Person{age: 22, name: "Silvia"}
|
|
|
|
assert Map.fetch(silvia, :age) == ___
|
|
end
|
|
|
|
defmodule Airline do
|
|
defstruct plane: %Plane{}, name: "Southwest"
|
|
end
|
|
|
|
koan "Use the put_in macro to replace a nested value" do
|
|
airline = %Airline{plane: %Plane{maker: :boeing}}
|
|
assert put_in(airline.plane.maker, :airbus) == ___
|
|
end
|
|
|
|
koan "Use the update_in macro to modify a nested value" do
|
|
airline = %Airline{plane: %Plane{maker: :boeing, passengers: 200}}
|
|
assert update_in(airline.plane.passengers, &(&1 + 2)) == ___
|
|
end
|
|
|
|
koan "Use the put_in macro with atoms to replace a nested value in a non-struct" do
|
|
airline = %{plane: %{maker: :boeing}, name: "Southwest"}
|
|
assert put_in(airline[:plane][:maker], :cessna) == ___
|
|
end
|
|
end
|