Jeweler: Craft the perfect RubyGem
Jeweler provides the noble ruby developer with two primary features:
- a library for managing and releasing RubyGem projects
- a scaffold generator for starting new RubyGem projects
Hello, world
Use RubyGems to install the heck out of jeweler to get started:
$ gem install jeweler
With jeweler installed, you can use the
jeweler command to generate a new project. For the most basic use, just give it a name:
$ jeweler hello-gem
This requires some Git configuration (like name, email, GitHub account, etc), but
jeweler will prompt along the way.
Your new
hello-gem gem is ready in the
hello-gem directory. Take a peek, and you'll see several files and directories
Rakefilesetup for jeweler, running tests, generating documentation, and releasing to rubygems.org
README.rdocwith contribution guidelines and copyright info crediting you
LICENSEwith the MIT licensed crediting you
Gemfilewith development dependencies filled in
lib/hello-gem.rbwaiting for you to code
test/containing a (failing) shoulda test suite shoulda
More
jeweler options
The
jeweler command supports a lot of options. Mostly, they are for generating baked in support for this test framework, or that.
jeweler --help for the most up to date options.
Hello, rake tasks
Beyond just editing source code, you'll be interacting with your gem using
rake a lot. To see all the tasks available with a brief description, you can run:
$ rake -T
You'll need a version before you can start installing your gem locally. The easiest way is with the
version:write Rake task. Let's imagine you start with 0.1.0
$ rake version:write MAJOR=0 MINOR=1 PATCH=0
You can now go forth and develop, now that there's an initial version defined. Eventually, you should install and test the gem:
$ rake install
The
install rake task builds the gem and
gem installs it. You're all set if you're using RVM, but you may need to run it with sudo if you have a system-installed ruby:
$ sudo rake install
Releasing
At last, it's time to ship it! Make sure you have everything committed and pushed, then go wild:
$ rake release
This will automatically:
- Generate
hello-gem.gemspecand commit it
- Use
gitto tag
v0.1.0and push it
- Build
hello-gem-0.1.0.gemand push it to rubygems.org
rake release accepts REMOTE(default:
origin), LOCAL_BRANCH(default:
master), REMOTE_BRANCH(default:
master) and BRANCH(default: master)as options.
$ rake release REMOTE=upstream LOCAL_BRANCH=critical-security-fix REMOTE_BRANCH=v3
This will tag and push the commits on your local branch named
critical-security-fix to branch named
v3 in remote named
upstream (if you have commit rights
on
upstream) and release the gem.
$ rake release BRANCH=v3
If both remote and local branches are the same, use
BRANCH option to simplify.
This will tag and push the commits on your local branch named
v3 to branch named
v3 in remote named
origin (if you have commit rights
on
origin) and release the gem.
Version bumping
It feels good to release code. Do it, do it often. But before that, bump the version. Then release it. There's a few ways to update the version:
# version:write like before
Then it's the same
release we used before:
$ rake release
Customizing your gem
If you've been following along so far, your gem is just a blank slate. You're going to need to make it colorful and full of metadata.
You can customize your gem by updating your
Rakefile. With a newly generated project, it will look something like this:. = ["Joshua Nichols"] end Jeweler::RubygemsDotOrgTasks.new
It's crucial to understand the
gem object is just a Gem::Specification. You can read up about it at guides.rubygems.org/specification-reference. This is the most basic way of specifying a gem, Jeweler-managed or not. Jeweler just exposes this to you, in addition to providing some reasonable defaults, which we'll explore now.
Project information
gem.name = "whatwhatwhat"
Every gem has a name. Among other things, the gem name is how you are able to
gem install it. Reference
gem.summary = %Q{TODO: one-line summary of your gem}
This is a one line summary of your gem. This is displayed, for example, when you use
gem list --details or view it on rubygems.org.
gem.description = %Q{TODO: longer description of your gem}
Description is a longer description. Scholars ascertain that knowledge of where the description is used was lost centuries ago.
gem.email = "josh@technicalpickles.com"
This should be a way to get a hold of you regarding the gem.
gem.homepage = ""
The homepage should have more information about your gem. The jeweler generator guesses this based on the assumption your code lives on GitHub, using your Git configuration to find your GitHub username. This is displayed by
gem list --details and on rubygems.org.
gem. = ["Joshua Nichols"]
Hey, this is you, the author (or me in this case). The
jeweler generator also guesses this from your Git configuration. This is displayed by
gem list --details and on rubygems.org.
Files
The quickest way to add more files is to
git add them. Jeweler uses your Git repository to populate your gem's files by including added and committed and excluding
.gitignored. In most cases, this is reasonable enough.
If you need to tweak the files, that's cool. Jeweler populates
gem.files as a
Rake::FileList. It's like a normal array, except you can
include and
exclude file globs:
gem.files.exclude 'tmp' # exclude temporary directory gem.files.include 'lib/foo/bar.rb' # explicitly include lib/foo/bar.rb
If that's not enough, you can just set
gem.files outright
gem.files = Dir.glob('lib/**/*.rb')
Dependencies
Dependencies let you define other gems that your gem needs to function.
gem install your-gem will install your-gem's dependencies along with it, and when you use your-gem in an application, the dependencies will be made available. Use
gem.add_dependency to register them. Reference
gem.add_dependency 'nokogiri'
This will ensure a version of
nokogiri is installed, but it doesn't require anything more than that. You can provide extra args to be more specific:
gem.add_dependency 'nokogiri', '= 1.2.1' # exactly version 1.2.1 gem.add_dependency 'nokogiri', '>= 1.2.1' # greater than or equal to 1.2.1, ie, 1.2.1, 1.2.2, 1.3.0, 2.0.0, etc gem.add_dependency 'nokogiri', '>= 1.2.1', '< 1.3.0' # greater than or equal to 1.2.1, but less than 1.3.0 gem.add_dependency 'nokogiri', '~> 1.2.1' # same thing, but more concise
When specifying which version is required, there's a bit of the condunrum. You want to allow the most versions possible, but you want to be sure they are compatible. Using
>= 1.2.1 is fine most of the time, except until the point that 2.0.0 comes out and totally breaks backwards the API. That's when it's good to use
~> 1.2.1, which requires any version in the
1.2 family, starting with
1.2.1.
Executables
Executables let your gem install shell commands. Just put any executable scripts in the
bin/ directory, make sure they are added using
git, and Jeweler will take care of the rest.
When you need more finely grained control over it, you can set it yourself:
gem.executables = ['foo'] # note, it's the file name relative to `bin/`, not the project root
Versioning
We discussed earlier how to bump the version. The rake tasks are really just convience methods for manipulating the
VERSION file. It just contains a version string, like
1.2.3.
VERSION is a convention used by Jeweler, and is used to populate
gem.version. You can actually set this yourself, and Jeweler won't try to override it:
gem.version = '1.2.3'
A common pattern is to have this in a version constant in your library. This is convenient, because users of the library can query the version they are using at runtime.
# in lib/foo/version.rb class Foo module Version MAJOR = 1 MINOR = 2 PATCH = 3 BUILD = 'pre3' STRING = [MAJOR, MINOR, PATCH, BUILD].compact.join('.') end end # in Rakefile require 'jeweler' require './lib/foo/version.rb' Jeweler::Tasks.new do |gem| # snip gem.version = Foo::Version::STRING end
Rake tasks
Jeweler lives inside of Rake. As a result, they are dear friends. But, that friendship doesn't interfere with typical Rake operations.
That means you can define your own namespaces, tasks, or use third party Rake libraries without cause for concern.
Contributing to Jeweler
- Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet
- Ask on the mailing list for feedback on your proposal, to see if somebody else has done it.
- Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it
- Fork the project
- Start a feature/bugfix branch
- Commit and push until you are happy with your contribution
- Make sure to add tests for the feature/bugfix. This is important so I don't break it in a future version unintentionally.
- Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate it to its own commit so I can cherry-pick around it.