ExPipeline

An opinionated library to build better pipelines.

Creating a Pipeline

On the module that will implement the pipeline, simplye use Pipeline and you are ready to go.

• A function is considered a step if its name ends with _step and accepts exactly two parameters
• A function is considered a callback if its name ends with _callback and accepts exactly two parameters
• Steps and callbacks are executed in the order they are declared
• Steps must always return an ok/error tuple: {:ok, value} or {:error, error}
• If one step fails, following steps will not be executed
• Callbacks are always executed after all steps are called, regardless of the final result.

An example:

defmodule MyModule do
  use Pipeline

  @doc """
  First step of the pipeline
  """
  def init_step(value, options) do
    # {:ok, updated_value}
    # or
    # {:error, some_error}
  end

  @doc """
  Second step of the pipeline
  """
  def second_step(value, options) do
    # {:ok, updated_value}
    # or
    # {:error, some_error}
  end

  @doc """
  Callback - always executed, results ignored
  """
  def report_callback(state, _options) do
    MyReportingModule.publish(state)
  end
end

With this module in place, you have two options to execute it:

• Calling the execute/2 function from your module
• Calling the execute/3 function from the Pipeline module

Both lines will execute the pipeline:

MyModule.execute(starting_value, options)
Pipeline.execute(MyModule, starting_value, options)

Installation

If available in Hex, the package can be installed by adding ex_pipeline to your list of dependencies in mix.exs:

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