gem-compiler

A RubyGems plugin that generates binary (pre-compiled) gems.

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Description

gem-compiler is a RubyGems plugin that helps generates binary gems from already existing ones without altering the original source code. It compiles Ruby C extensions and bundles the result into a new gem.

It uses an outside-in approach and leverages on existing RubyGems code to do it.

The result of the compilation is a binary gem built for your current platform, skipping the need of a compiler toolchain when installing it.

Installation

To install gem-compiler you need to use RubyGems:

$ gem install gem-compiler

Which will fetch and install the plugin. After that the compile command will be available through gem.

Usage

As requirement, gem-compiler can only compile local gems, either one you have generated from your projects or previously downloaded.

Fetching a gem

If you don't have the gem locally, you can use fetch to retrieve it first:

$ gem fetch yajl-ruby --platform=ruby
Fetching: yajl-ruby-1.1.0.gem (100%)
Downloaded yajl-ruby-1.1.0

Please note that I was explicit about which platform to fetch. This will avoid RubyGems attempt to download any existing binary gem for my current platform.

Compiling a gem

You need to tell RubyGems the filename of the gem you want to compile:

$ gem compile yajl-ruby-1.1.0.gem

The above command will unpack, compile any existing extensions found and repackage everything as a binary gem:

Unpacking gem: 'yajl-ruby-1.1.0' in temporary directory...
Building native extensions.  This could take a while...
  Successfully built RubyGem
  Name: yajl-ruby
  Version: 1.1.0
  File: yajl-ruby-1.1.0-x86-mingw32.gem

This new gem do not require a compiler, as shown when locally installed:

C:\> gem install --local yajl-ruby-1.1.0-x86-mingw32.gem
Successfully installed yajl-ruby-1.1.0-x86-mingw32
1 gem installed

Compiling from Rake

Most of the times, as gem developer, you would like to generate both kind of gems at once. For that purpose, you can add a task for Rake similar to the one below:

desc "Generate a pre-compiled native gem"
task "gem:native" => ["gem"] do
  sh "gem compile #{gem_file}"
end

Of course, that assumes you have a task gem that generates the base gem required.

Requirements

Ruby and RubyGems

It's assumed you have Ruby and RubyGems installed. gem-compiler requires RubyGems 1.8.x to properly work.

If you don't have RubyGems 1.8.x, you can upgrade by running:

$ gem update --system

A compiler

In order to compile a gem, you need a compiler toolchain installed. Depending on your Operating System you will have one already installed or will require additional steps to do it. Check your OS documentation about getting the right one.

If you're using Windows

For those using RubyInstaller-based builds, you will need to download the DevKit from their downloads page and follow the installation instructions.

To be sure your installation of Ruby is based on RubyInstaller, execute at the command prompt:

C:\> ruby --version

And from the output:

tcs-ruby 1.9.3p196 (2012-04-21, TCS patched 2012-04-21) [i386-mingw32]

If you see mingw32, that means you're using a RubyInstaller build (MinGW based).

Differences with rake-compiler

rake-compiler has provided to Ruby library authors a tool for compiling extensions and generating binary gems of their libraries.

You can consider rake-compiler's approach be an inside-out process. To do its magic, it requires library authors to modify their source code, adjust some structure and learn a series of commands.

While the ideal scenario is using a tool like rake-compiler that endorses convention over configuration, is not humanly possible change all the projects by snapping your fingers 😉

What is missing

The following are the list of features I would like to implement at some point:

• Cross compile gems to any platform that Ruby can run (e.g. from Linux/OSX to Windows, x86 to x64, x86 Linux to ARM Linux, etc)

• Create multiple gems from the same build (e.g. target both x86-mswin32-60 and x86-mingw32)

• Ability to build fat-binaries targeting both Ruby 1.8 and 1.9.x, placing automatic stubs to handle extension loading.

License

(The MIT License)

Copyright (c) Luis Lavena

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.