ExCut [cross-cut]

Motivation

ExCut defines an annotation construct that wraps a regular function and enable it to be decorated with a cross-cutting concern. This provide a clean mechanism to inject reusable behavior without cluttering your code base.

Documentation

ExCut

Examples

ExCut Examples

Installation

Add the following dependencies to your Elixir project

def deps do
  [
    {:ex_cut , "~> 0.1.0"}
  ]
end

Using

Let's take a look at ExCut in action to add logging behavior to a set of functions.

defmodule Logging do
  use ExCut, marker: :log, pre: :pre, post: :post

  require Logger

  @log level: :warn
  def elvis(a, b) when is_boolean(a), do: b

  @log level: :debug
  def elvis(a, b) when is_atom(a), do: "#{a}--#{b}"

  @log level: :info
  def elvis(a, b), do: a + b

  defp pre(c)       , do: "> #{c.target}(#{c.args |> inspect})" |> log(c)
  defp post(c, _, r), do: "< #{c.target} -> #{r}"               |> log(c)

  defp log(m, ctx) do
    ctx.meta[:level]
    |> case do
      :warn  -> m |> Logger.warn
      :debug -> m |> Logger.debug
      _      -> m |> Logger.info
    end
  end
end

ExCut provisions an ExCut.Context with call details and metadata that comes from the annotation. You can leverage this information in your cross-cutting functions.

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© 2017 Imhotep Software LLC. All materials licensed under Apache v2.0