A tool helps you answering the question: why editing this file cause 127 other files to recompile?

Installation

The package can be installed by adding why_recompile to your list of dependencies in mix.exs:

def deps do
  [{:why_recompile, "~> 0.1", only: [:dev], runtime: false}]
end

Basic Usage

The package provides some Mix tasks to explore the recompile depedency graph of your project. To see the full commands documentation:

mix why_recompile help

mix why_recompile list

List all files in the project sorted by number of recompile dependencies. If A is a recompile depedency of B, when B is recompiled, A must be recompiled as well.

[!NOTE] There are two kind of dependencies. Given two files A and B:

1. Hard dependencies: if A is a hard depedency of B, when B is recompiled, A MUST be recompiled
2. Soft dependencies: if A is a hard depedency of B, when B is recompiled, A MIGHT have to recompiled

An example for soft dependencies: when A uses struct from B, if B is recompiled but doesn't change the struct definition, A won't need to be recompiled. Otherwise, A needs to be recompiled.

# List all files in the project
mix why_recompile list

# List all files in the project, include files with no dependencies
mix why_recompile list --all

# Only list top 5 files
mix why_recompile list --limit 5

mix why_recompile show

Show all the recompile dependencies of a file and the detailed explanation of such depedency.

# Provide the file path
mix why_recompile show lib/A.ex

You can increase the verbosity to see more details about the depedency.

# Print the whole dependency chain
mix why_recompile show lib/A.ex --verbose 1

# Print the whole dependency chain and code snippets that cause the dependency
mix why_recompile show lib/A.ex --verbose 2

To filter by dependency name (support partial match):

mix why_recompile show lib/A.ex --filter C.ex

To include soft dependencies:

mix why_recompile show lib/A.ex --include-soft