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exop

1.1.4
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A library that provides a few macros which allow you to encapsulate business logic and validate incoming params over predefined contract.

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exop lib exop policy.ex
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lib/exop/policy.ex 

defmodule Exop.Policy do

  @moduledoc """

  Provides macros for policy validation.



  ## Example



      defmodule MonthlyReportPolicy do

        # not only Keyword or Map as an argument since 1.1.1

        def can_read?(%{user_role: "admin"}), do: true

        def can_read?("admin"), do: true

        def can_read?(%User{role: "manager"}), do: true

        def can_read?(:manager), do: true

        def can_read?(_opts), do: false



        def can_write?(%{user_role: "manager"}), do: true

        def can_write?(_opts), do: false

      end



      defmodule ReadOperation do

        use Exop.Operation



        policy MonthlyReportPolicy, :can_read?



        parameter :user, required: true, struct: %User{}



        def process(params) do

          authorize(params.user)



          # make some reading...

        end

      end



  If authorization fails, any code after (below) auth check is postponed:

  an error `{:error, {:auth, _reason}}` is returned immediately.

  """



  @type t :: __MODULE__



  @doc """

  Authorizes the possibility to invoke an action.

  """

  @callback authorize(atom, any()) :: true | false



  defmacro __using__(_opts) do

    quote do

      @behaviour unquote(__MODULE__)

      import unquote(__MODULE__)

      @before_compile unquote(__MODULE__)

    end

  end



  defmacro __before_compile__(_env) do

    quote do

      @spec authorize(atom, any()) :: true | false

      def authorize(action, opts), do: apply(__MODULE__, action, [opts]) == true

    end

  end

end