View Source Home

Igniter

Igniter is a code generation and project patching framework.

For library authors, this is a tool kit for writing smarter generators that can semantically modify existing files.

For end-users, this means mix igniter.install <package>, which will add it to your mix.exs automatically and then run that library's installer if it has one. Even when libraries don't have an installer, or use igniter, this behavior makes it useful to keep around.

Limitations

Right now, all files that are touched are formatted in their entirety. This may be a deal breaker for some users. I believe that we can solve this without changing the fundemental design of the project, but it is not a high priority.

Installation

Igniter can be added to an existing elixir project by adding it to your dependencies:

{:igniter, "~> 0.1"}

You can also generate new projects with igniter preinstalled, and run installers in the same command.

First, install the archive:

mix archive.install hex igniter_new

Then you can run mix igniter.new

mix igniter.new app_name --install ash

Or if you want to use a different project creator, specify the mix task name with the --with flag. Any arguments will be passed through to that task, with the exception of --install and --example.

mix igniter.new app_name --install ash --with phx.new --no-ecto

Patterns

Mix tasks built with igniter are both individually callable, and composable. This means that tasks can call eachother, and also end users can create and customize their own generators composing existing tasks.

Installers

Igniter will look for a task called <your_package>.install when the user runs mix igniter.install <your_package>, and will run it after installing and fetching dependencies.

Generators/Patchers

These can be run like any other mix task, or composed together. For example, lets say that you wanted to have your own Ash.Resource generator, that starts with the default mix ash.gen.resource task, but then adds or modifies files:

# in lib/mix/tasks/my_app.gen.resource.ex
defmodule Mix.Tasks.MyApp.Gen.Resource do
  use Igniter.Mix.Task

  def igniter(igniter, [resource | _] = argv) do
    resource = Igniter.Code.Module.parse(resource)
    my_special_thing = Module.concat([resource, SpecialThing])
    location = Igniter.Code.Module.proper_location(my_special_thing)

    igniter
    |> Igniter.compose_task("ash.gen.resource", argv)
    |> Igniter.create_new_elixir_file(location, """
    defmodule #{inspect(my_special_thing)} do
      # this is the special thing for #{inspect()}
    end
    """)
  end
end