常量作为函数

声明：

defmodule MyApp.ViaFunctions.Constants do
  def app_version, do: "0.0.1"
  def app_author, do: "Felix Orr"
  def app_info, do: [app_version, app_author]
  def bar, do: "barrific constant in function"
end

消费需求：

defmodule MyApp.ViaFunctions.ConsumeWithRequire do
  require MyApp.ViaFunctions.Constants

  def foo() do
    IO.puts MyApp.ViaFunctions.Constants.app_version
    IO.puts MyApp.ViaFunctions.Constants.app_author
    IO.puts inspect MyApp.ViaFunctions.Constants.app_info
  end

  # This generates a compiler error, cannot invoke `bar/0` inside a guard.
  # def foo(_bar) when is_bitstring(bar) do
  #   IO.puts "We just used bar in a guard: #{bar}"
  # end
end

消费与导入：

defmodule MyApp.ViaFunctions.ConsumeWithImport do
  import MyApp.ViaFunctions.Constants

  def foo() do
    IO.puts app_version
    IO.puts app_author
    IO.puts inspect app_info
  end
end

此方法允许跨项目重用常量，但它们不能在需要编译时常量的保护函数中使用。