git-filter-demo

Demonstrate use of Git filters to auto-format code to your preferred indentation style during checkout and staging.

The C source files use MuseScore's coding rules, which specify 6 space indentation with banner style braces. This is not a popular code style, but the point is to demonstrate how you can change it to something that you are more familiar with without affecting other developers.

Instructions

1. Get the code

git clone https://github.com/shoogle/git-filter-demo.git
cd git-filter-demo

Or fork the project on GitHub and clone your fork.

2. Setup filter to autoformat C code

A filter named indent_cpp is declared in .gitattributes. You need to define the commands it should execute during checkout and checkin:

# Checkout K&R style:
git config filter.indent_cpp.smudge "lint/uncrustify/wrapper.sh -c lint/uncrustify/kr.cfg"

# Checkin MuseScore style:
git config filter.indent_cpp.clean "lint/uncrustify/wrapper.sh -c lint/uncrustify/musescore.cfg"

You could checkout to a different style if you prefer, but you should always checkin with the MuseScore style to match the existing code.

3. Edit some files

Make some changes to one of the .c or .h files and see how utilities like git status and git diff are affected by the filter. You need to install uncrustify for the filter to work.

Optional: Define more filters!

If you want other types of file to be autoformatted, such as the CMake build scripts (CMakeLists.txt, *.cmake, etc.), then you need to declare more filters in .gitattributes or .git/info/attributes. Rules declared in .gitattributes affect all developers, while rules declared in .git/info/attributes are personal to you.