Creating Ruby Gems bespoke for DVELP.md

Creating Ruby Gems bespoke for DVELP

Prerequisites

1. Configure bundler:

   bundle config gem.test rspec

   • Other popular config options include:

   bundle config build.nokogiri --use-system-libraries

   bundle config gem.coc true (adds Code of Conduct.md)

   bundle config gem.mit true (adds MIT License to License.txt)

Setup

1. Create the gem scaffold:

   bundle gem ${gem_name}

2. Gitignore Gemfile.lock if it hasn't already been ignored. [2]

3. Update ${gem_name}.gemspec

4. Add CLI if needed (with install command): [5]

• Add spec.add_dependency 'thor' to ${gem_name}.gemspec & bundle install

cd ${gem_name}
mkdir -p lib/${gem_name}/cli/install_files
mkdir exe
module_name=`echo ${gem_name:0:1} | tr '[a-z]' '[A-Z]'`${gem_name:1}

cat <<EOT > lib/${gem_name}/cli/install.rb
require 'thor/group'

module ${module_name}
  class CLI < Thor
    class Install < Thor::Group
      include Thor::Actions

      def self.start
        source_root = File.expand_path('../install_files', __FILE__)
        FileUtils.cp_r "#{source_root}/.", Dir.pwd
      end
    end
  end
end
EOT

cat <<EOT > lib/${gem_name}/cli.rb
require 'thor'

module ${module_name}
  class CLI < Thor
    # ${gem_name} install

    desc 'install', 'Install ${module_name}'
    def install
      # make require here to hide it from Thor CLI actions
      require '${gem_name}/cli/install'
      Install.start
    end
  end
end
EOT

cat <<EOT > exe/${gem_name}
#!/usr/bin/env ruby

require '${gem_name}/cli'

${module_name}::CLI.start
EOT

chmod +x exe/${gem_name}

• Add any files you want copied on install action to lib/${gem_name}/cli/install_files
• Keep in mind that when you install gem with rake install, you need to reload shell to be able to execute the CLI commands

Usefull commands

• bundle install - install dependency gems
• rake install - install the gem; requires changes to be committed!
• bundle console - similar to rails console
• bundle exec ${file_name} - runs the script with the current gem environment

Remarks

All gem specific code should go in lib/${gem_name} and be nested inside module ${module_name}. This prevents name collisions as module acts as namespace.

Sources

1. $ bundle help

• Why gitignore Gemfile.lock
• Gem development
• Figaro gem example
• Thor

---

Note that you can set shell variables like this gem_name="nelly", and run most of the commands without having to change anything. Here's the list of variables needed:

gem_name=""