A generator for Ruby FFI bindings, directly from header files via LLVM's Clang compiler
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Latest commit 48a2e4c Jan 25, 2015 @whitequark whitequark Bump version.


A generator for Ruby FFI bindings

Author: Richard Musiol Contributors: Jeremy Voorhis (thanks for the initial idea) License: MIT (see LICENSE)


  • Generation of FFI methods, structures, unions, enumerations and callbacks
  • Generation of YARD documentation comments
  • Tested with headers of the following libraries:
    • Cairo
    • CEF (Chromium Embedded Framework)
    • Clang
    • LibSSH2
    • LLVM
    • OpenGL
    • SQLite3


  • Ruby 1.9
  • Clang 3.5 or later (Download the binaries or build from source configured with --enable-shared)

These requirements are only for running the generator. The generated files are Ruby 1.8 compatible and do not need Clang.


Use the following interface in a script or Rake task:

require "ffi_gen"

  module_name: "Clang",
  ffi_lib:     "clang",
  headers:     ["clang-c/Index.h"],
  cflags:      `llvm-config --cflags`.split(" "),
  prefixes:    ["clang_", "CX"],
  output:      "clang-c/index.rb"

Output: clang-c/index.rb

Other generated files can be found in the test/output directory.


You may need to set additional include directories:

export CPATH=/usr/lib/gcc/x86_64-linux-gnu/4.6.1/include

Your GCC include paths can be seen with:

`gcc -print-prog-name=cc1` -v

Projects using ffi_gen


  • Support for more libraries:
    • (Write me if you have a whish)
  • Automatic generation of object oriented wrappers
  • Polish YARD documentation comments some more


Please use GitHub's issue tracker for problems or suggestions. Pull requests are welcome, too.