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clang-format With Explicit Format File

Posted 2019-02-15

clang-format is a great code formatter for C and C++ code, but using it can be annoying due to the way the format file is specified. There is no option to pick your format file explicitly. Instead, clang-format will look for a file called .clang-format or _clang-format in your working directory, and then search recursively upward through the tree until it finds that file.

That doesn't really work for me. I have a .clang-format file I keep in my dotfiles repo, and I'd like to use that for all of my code formatting. Unfortunately this file won't get used unless there are no other .clang-format files anywhere in the path from my code directory to my home directory root, and that doesn't work for me. For reasons not worth getting into, I often find a .clang-format file in the way in the way.

Now certainly, you could fix this issue by symlinking my global .clang-format into every code project directory, but that gets pretty annoying as well.

Instead, here's my solution. clang-format offers a -style option that lets you specify a YAML dictionary of all your style options on the command line. I made a script that acts as a wrapper around clang-format. It parses whatever .clang-format file you want, formats it into a single arg, then calls clang-format passing your style information to the -style argument.

Hope this helps anyone out there!

#!/usr/bin/env python3

# Note: depends on you having the pyyaml module installed.

import os
import yaml
import sys
import subprocess

p = os.path.expanduser("~/.clang-format")

clangf = open(p, 'r')
clangfc = clangf.read()

yl = yaml.load(clangfc)

ret = subprocess.run(["clang-format-6.0", "-style", str(yl)] + sys.argv[1:])


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