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