From 1d1542e62fc03d3271dbbbcf10df2edd40f9455c Mon Sep 17 00:00:00 2001
From: Matt Enlow <enlow@adobe.com>
Date: Wed, 12 Jun 2024 15:23:32 -0700
Subject: [PATCH] module directives

---
 README.md                 |  25 +++++++-
 docs/module_directives.md | 116 +++++++++++++++++++++++++++++++++++++-
 2 files changed, 137 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index 986dfd7..a193297 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,30 @@ you what's wrong, it just rewrites the code for you to fit its style rules.
 
 You can learn more about the history, purpose and implementation of Styler from our talk: [Styler: Elixir Style-Guide Enforcer @ GigCity Elixir 2023](https://www.youtube.com/watch?v=6pF8Hl5EuD4)
 
-[See our Rewrites documentation on hexdocs for details on what all Styler does](https://hexdocs.pm/styler/)
+## Features
+
+- auto-fixes [many credo rules](docs/credo.md), meaning you can turn them off to speed credo up
+- [keeping a strict module layout](docs/module_directives.md#directive-organization)
+- alphabetizing module directives
+- [extracting repeated aliases](docs/moduledirectives.md#alias-lifting)
+- piping and unpiping function calls based on the number of functons
+- optimizing standard library calls (`a |> Enum.map(m) |> Enum.into(Map.new)` => `Map.new(a, m)`)
+- using sigils for strings with many escaped quotes `\"`
+- ... and so many other things.
+
+[See our Rewrites documentation on hexdocs for all the nitty-gritty on what all Styler does](https://hexdocs.pm/styler/)
+
+## Who is Styler for?
+
+Styler was designed for a large team (40+ engineers) working in a single codebase. It helps remove fiddly code review comments and removes failed linter CI slowdowns, helping teams get things done faster. Teams in similar situations might appreciate Styler.
+
+Its automations are also extremely valuable for taming legacy elixir codebases or just refactoring in general. Some of its rewrites have inspired code actions in elixir language servers.
+
+Conversely, Styler probably _isn't_ a good match for:
+
+- libraries
+- experimental, macro-heavy codebases
+- small teams that don't want to think about code standards
 
 ## Installation
 
diff --git a/docs/module_directives.md b/docs/module_directives.md
index d772504..0c725c4 100644
--- a/docs/module_directives.md
+++ b/docs/module_directives.md
@@ -19,11 +19,11 @@ Adds `@moduledoc false` to modules without a moduledoc unless the module's name
 Expands `Module.{SubmoduleA, SubmoduleB}` to their explicit forms for ease of searching.
 
 ```elixir
-# Given
+# Before
 import Foo.{Bar, Baz, Bop}
 alias Foo.{Bar, Baz.A, Bop}
 
-# Styled
+# After
 import Foo.Bar
 import Foo.Baz
 import Foo.Bop
@@ -46,9 +46,87 @@ Modules directives are sorted into the following order:
 * `require` (sorted alphabetically)
 * everything else (order unchanged)
 
+### Before
+
+```elixir
+defmodule Foo do
+  @behaviour Lawful
+  alias A.A
+  require A
+
+  use B
+
+  def c(x), do: y
+
+  import C
+  @behaviour Chaotic
+  @doc "d doc"
+  def d do
+    alias X.X
+    alias H.H
+
+    alias Z.Z
+    import Ecto.Query
+    X.foo()
+  end
+  @shortdoc "it's pretty short"
+  import A
+  alias C.C
+  alias D.D
+
+  require C
+  require B
+
+  use A
+
+  alias C.C
+  alias A.A
+
+  @moduledoc "README.md"
+             |> File.read!()
+             |> String.split("<!-- MDOC !-->")
+             |> Enum.fetch!(1)
+end
+```
+
+### After
+
 ```elixir
-defmodule OrganizeMe do
+defmodule Foo do
+  @shortdoc "it's pretty short"
+  @moduledoc "README.md"
+             |> File.read!()
+             |> String.split("<!-- MDOC !-->")
+             |> Enum.fetch!(1)
+  @behaviour Chaotic
+  @behaviour Lawful
 
+  use B
+  use A.A
+
+  import A.A
+  import C
+
+  alias A.A
+  alias C.C
+  alias D.D
+
+  require A
+  require B
+  require C
+
+  def c(x), do: y
+
+  @doc "d doc"
+  def d do
+    import Ecto.Query
+
+    alias H.H
+    alias X.X
+    alias Z.Z
+
+    X.foo()
+  end
 end
 ```
 
@@ -65,3 +143,35 @@ alias Foo.Bar
 ```
 
 ## Alias Lifting
+
+When a module with three parts is referenced two or more times, styler creates a new alias for that module and uses it.
+
+```elixir
+# Given
+require A.B.C
+
+A.B.C.foo()
+A.B.C.bar()
+
+# Styled
+alias A.B.C
+
+require C
+
+C.foo()
+C.bar()
+```
+
+### Collisions
+
+Styler won't lift aliases that will collide with existing aliases, and likewise won't lift any module whose name would collide with a standard library name.
+
+You can specify additional modules to exlude from lifting via the `:alias_lifting_exclude` configuration option. For the example above, the following configuration would keep Styler from creating the `alias A.B.C` node:
+
+```elixir
+# .formatter.exs
+[
+  plugins: [Styler],
+  styler: [alias_lifting_exclude: [:C]],
+]
+```