60 lines
1.4 KiB
Elixir
60 lines
1.4 KiB
Elixir
defmodule Structs do
|
|
use Koans
|
|
|
|
defmodule Person do
|
|
defstruct [:name, :age ]
|
|
end
|
|
|
|
koan "structs are defined and named after a module" do
|
|
person = %Person{}
|
|
assert person == %Person{}
|
|
end
|
|
|
|
koan "you can access the fields of a struct" do
|
|
nobody = %Person{}
|
|
assert nobody.age == nil
|
|
assert nobody.name == nil
|
|
end
|
|
|
|
koan "You can pass initial values to structs" do
|
|
joe = %Person{name: "Joe", age: 23}
|
|
assert joe.age == 23
|
|
assert joe.name == "Joe"
|
|
end
|
|
|
|
koan "update fields with the pipe '|' operator" do
|
|
joe = %Person{name: "Joe", age: 23}
|
|
older = %{ joe | age: joe.age + 10}
|
|
assert older.age == 33
|
|
end
|
|
|
|
koan "the original struct is not affected by updates" do
|
|
joe = %Person{name: "Joe", age: 23}
|
|
assert %{ joe | age: joe.age + 10}.age == 33
|
|
assert joe.age == 23
|
|
end
|
|
|
|
koan "you can pattern match into the fields of a struct" do
|
|
%Person{age: age} = %Person{age: 22, name: "Silvia"}
|
|
assert age == 22
|
|
end
|
|
|
|
defmodule Plane do
|
|
defstruct passengers: 0, maker: :boeing
|
|
end
|
|
|
|
koan "or onto the type of the struct itself" do
|
|
assert is_a_plane(%Plane{passengers: 417, maker: :boeing})
|
|
refute is_a_plane(%Person{age: 22, name: "Silvia"})
|
|
end
|
|
|
|
def is_a_plane(%Plane{}), do: true
|
|
def is_a_plane(_), do: false
|
|
|
|
koan "are basically maps" do
|
|
silvia = %Person{age: 22, name: "Silvia"}
|
|
|
|
assert Map.fetch!(silvia, :age) == 22
|
|
end
|
|
end
|