# 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

 * `Rakefile` setup for jeweler, running tests, generating documentation, and releasing to [rubygems.org](http://rubygems.org/)
 * `README.rdoc` with contribution guidelines and copyright info crediting you
 * `LICENSE` with the MIT licensed crediting you
 * `Gemfile` with development dependencies filled in
 * `lib/hello-gem.rb` waiting for you to code
 * `test/` containing a (failing) shoulda test suite [shoulda](http://github.com/thoughtbot/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.

Check out `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 install`s it. You're all set if you're using [RVM](http://rvm.beginrescueend.com/), 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](http://img.skitch.com/20100310-nrgxbwqm58tibiq2un6mujqmm5.png)! Make sure you have everything committed and pushed, then go wild:

    $ rake release

This will automatically:

 * Generate `hello-gem.gemspec` and commit it
 * Use `git` to tag `v0.1.0` and push it
 * Build `hello-gem-0.1.0.gem` and push it to [rubygems.org](http://rubygems.org/gems/)

### 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
    $ rake version:write MAJOR=0 MINOR=3 PATCH=0

    # bump just major, ie 0.1.0 -> 1.0.0
    $ rake version:bump:major

    # bump just minor, ie 0.1.0 -> 0.2.0
    $ rake version:bump:minor

    # bump just patch, ie 0.1.0 -> 0.1.1
    $ rake version:bump:patch

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:

    require 'jeweler'
    Jeweler::Tasks.new do |gem|
      # gem is a Gem::Specification... see http://docs.rubygems.org/read/chapter/20 for more options
      gem.name = "whatwhatwhat"
      gem.summary = %Q{TODO: one-line summary of your gem}
      gem.description = %Q{TODO: longer description of your gem}
      gem.email = "josh@technicalpickles.com"
      gem.homepage = "http://github.com/technicalpickles/whatwhatwhat"
      gem.authors = ["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 [docs.rubygems.org/read/chapter/20](http://docs.rubygems.org/read/chapter/20). 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](http://docs.rubygems.org/read/chapter/20#name)

    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](http://rubygems.org/gems/).

    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 = "http://github.com/technicalpickles/whatwhatwhat"

The homepage should have more information about your gem. The jeweler generator guesses this based on the assumption your code lives on [GitHub](http://github.com/), using your Git configuration to find your GitHub username. This is displayed by `gem list --details` and on rubygems.org.

    gem.authors = ["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 `.gitignore`d. 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](http://docs.rubygems.org/read/chapter/20#dependencies)

    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
* Check out the [issue tracker](http://github.com/technicalpickles/jeweler/issues) 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.

## Copyright

Copyright (c) 2008-2010 Josh Nichols. See LICENSE for details.
