Vials

This project is not quite ready for primetime yet. I'm not accepting PRs at this time as I'm doing a bunch of refactoring.

Vials are bits of code that can be seamlessly run after a mix task.

At present, the DSL is geared toward altering the output of generators, but that could change.

For example, here is a vial around phx.new:

# ~/vials/phx.new.ex
defmodule Phx.New do
  use Vials

  base_path @target

  remove "priv/static/favicon.ico"
end

Note: @target refers to the first argument passed to the mix task. More info below.

Run it with:

$ vials phx.new my_project

Vials will load the module defined in ~/vials/phx.new.ex, run $ mix phx.new my_project as normal then remove my_project/priv/static/favicon.ico.

Vials are searched for in ~/vials, ~/.vials, or $VIAL_PATH (arguments for changing this are coming).

Positional arguments passed to the wrapped task are available in a integer-indexed map as @args (available as @args._0, @args._1, etc) whereas the options map is available as @opts. @target is set to the first argument given to the mix task (i.e., @args._1) whereas, for completeness, @task_name is set to the mix task's name (i.e., @args._0).

For example, with this command:

$ vials phx.new my_project --module MyLongerProjectName --binary-id

...we can do the following:

defmodule Phx.New do
  use Vials

  base_path @target

  if @opts[:binary_id] do
    create "lib/#{@target}/schema", """
    defmodule #{@opts.module}.Schema do
      defmacro __using__(_) do
        quote do
          use Ecto.Schema, warn: false

          @primary_key {:id, :binary_id, autogenerate: true}
          @foreign_key_type :binary_id
        end
      end
    end
    """
  end
end

You could also add a vial for ecto.gen.migration do to play nicer with projects using --binary-id:

# ~/vials/ecto.gen.migrations.ex
defmodule Ecto.Gen.Migration do
  use Vials

  # Don't need to set the base_path here since we run this from within our
  # project.

  if Path.wildcard("lib/*/schema.ex") |> Enum.any?() do
    edit "*_{@target}.exs", fn contents ->
      if contents =~ `def create table` do
        String.replace(contents, ~r/def create.*/, """
            def change table(#{@target}, primary_key: false) do
              add :id, :binary_id, primary_key: true

              timestamps()
        """
      else
        contents
      end
    end
  end
end

As you can see, editing files is a bit crude right now, but improvements will be coming soon including being able to get the contents as a Sourceror AST.

Experimental features

I'm fairly new to AST manipulation so you'll have to bear with me.

At the moment, if you pass a block to create you can just write straight, static Elixir:

create "lib/some_file.ex" do
  defmodule SomeFile do
    def hi do
      "hi"
    end
  end
end

There is currently no way to inject the variable module attributes but I'm working on that.

Current API

base_path/1: Sets the base path for where to look for all subsequent filenames. You only need this if you are wrapping a task like mix phx.new where you want to run commands relative to the new projects root without actually cd'ing into it.

create/2: Creates a file. Takes a filename and contents as strings.

edit/2: Edits a file. Takes a wildcard, filename, or list of filenames and passes the contents of each match to an anonymous function.

remove/1: Removes a file.

add_dep/1: Adds a dependency, eg: add_dep {:some_dep, "~> 0.0.1"}

remove_comments/0: Removes all comments from ex and exs files.

remove_comments/1: Takes a filename or list of filenames to remove comments from.

Coming soon

• More DSL functions for common mix-related operations.
• A plugin system for task-specific operations, like starting a phoenix project using utc_timestamp_usec by default, for example.
• A way of passing an alternate directory or filename as an argument instead of looking for the default vial.

Installation

Vials is not yet on hexpm. You can clone the repo and build it with mix escript build from within the project's root. This will create a vials executable which you can move to some directory in your PATH.