ClangFormatAllTheThings.md

% ClangFormat All The Things % Andrew Seidl % 27 February 2015

ClangFormat All The Things

ClangFormat

• C/C++/ObjC source code formatter
  • like astyle, autopep8, go-fmt
• Part of the Clang/LLVM project
  • note: Apple doesn't include it with Xcode

Why?

• we have all seen some pretty horrible looking code
• w/o shared editor settings, each dev is responsible for config'ing editor
• mitigate flamewars
  • BDFL sets repo standard, dissenters use git hooks

Example: from this...

struct  ChThreadConstructionInfo
  {
    ChThreadConstructionInfo(char* uniqueName,
                  int numThreads=1,
                  int threadStackSize=65535
                  )
                  :m_uniqueName(uniqueName),
                  m_numThreads(numThreads),
                  m_threadStackSize(threadStackSize)
    {

    }

    char*         m_uniqueName;
    int           m_numThreads;
    int           m_threadStackSize;

  };

Example: ...to this (Chromium style)

struct ChThreadConstructionInfo {
  ChThreadConstructionInfo(char *uniqueName,
                           int numThreads = 1,
                           int threadStackSize = 65535)
      : m_uniqueName(uniqueName),
        m_numThreads(numThreads),
        m_threadStackSize(threadStackSize) {}

  char *m_uniqueName;
  int m_numThreads;
  int m_threadStackSize;
};

How?

• style specified in .clang-format file in top source dir
  • builtins: LLVM, Google, Chromium, Mozilla, WebKit
  • can BasedOnStyle, then override specifics
• can be run from command line or inside editor

BasedOnStyle: Chromium

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Editor Support

• Eclipse: https://github.com/wangzw/cppstyle
• Emacs: http://clang.llvm.org/docs/ClangFormat.html
• SublimeText: https://github.com/rosshemsley/SublimeClangFormat
• Vim: https://github.com/rhysd/vim-clang-format
• Visual Studio: http://llvm.org/builds/
• Xcode: https://github.com/travisjeffery/ClangFormat-Xcode

Links

• ClangFormat: http://clang.llvm.org/docs/ClangFormat.html

• Style options: http://clang.llvm.org/docs/ClangFormatStyleOptions.html

• .clang-format builder: http://clangformat.com/

• Style comparison: http://git.io/xtW5

• Blog post: forthcoming, will issue PR when ready

ALL THE C (segue to Olympics)

find . \( -regex '.*\.\(cpp\|cu\|h\)' ! -ipath 'thirdparty' \) -exec clang-format -i '{}' \;