source 'https://rubygems.org'
 
# Ruby version
ruby '3.3.0'
 
# Production gems
gem 'rails', '~> 7.1'
gem 'pg', '>= 1.1'
gem 'puma', '~> 6.0'
 
# Development and test gems
group :development, :test do
  gem 'rspec-rails'
  gem 'factory_bot_rails'
  gem 'faker'
end
 
# Development only
group :development do
  gem 'rubocop'
  gem 'rubocop-rails'
end
 
# Test only
group :test do
  gem 'capybara'
  gem 'selenium-webdriver'
end
 
# Git source
gem 'my_gem', git: 'https://github.com/user/my_gem.git'
 
# Local path (for development)
gem 'local_gem', path: '../local_gem'
 
# Specific branch
gem 'experimental_gem', git: 'https://github.com/user/repo.git', branch: 'develop'
 
# Require specific file or false to not auto-require
gem 'sidekiq', require: 'sidekiq/web'
gem 'bootsnap', require: false

# Exact version
gem 'rails', '7.1.0'
 
# Pessimistic operator (allows patch updates)
gem 'rails', '~> 7.1.0'  # >= 7.1.0 and < 7.2.0
gem 'rails', '~> 7.1'    # >= 7.1.0 and < 8.0.0
 
# Greater than or equal
gem 'pg', '>= 1.1'
 
# Range
gem 'ruby-version', '>= 1.0', '< 2.0'
 
# Multiple constraints
gem 'nokogiri', '>= 1.10', '< 2.0'

# Install all gems from Gemfile
bundle install
 
# Install to specific path
bundle install --path vendor/bundle
 
# Update all gems
bundle update
 
# Update specific gem
bundle update rails
 
# Check for outdated gems
bundle outdated
 
# Show gem location
bundle show rails
 
# Execute command with bundled gems
bundle exec rspec
 
# Open gem in editor
bundle open rails
 
# Check Gemfile syntax
bundle check
 
# Remove unused gems
bundle clean
 
# List all installed gems
bundle list
 
# Show dependency tree
bundle viz

# Always commit Gemfile.lock to version control
# This ensures all developers use same gem versions
 
# Regenerate Gemfile.lock
rm Gemfile.lock
bundle install

# Create new gem
bundle gem my_gem
 
# Structure:
my_gem/
├── lib/
│   ├── my_gem/
│   │   └── version.rb
│   └── my_gem.rb
├── spec/
│   ├── my_gem_spec.rb
│   └── spec_helper.rb
├── bin/
│   ├── console
│   └── setup
├── .gitignore
├── Gemfile
├── LICENSE.txt
├── my_gem.gemspec
├── Rakefile
└── README.md

# my_gem.gemspec
require_relative 'lib/my_gem/version'
 
Gem::Specification.new do |spec|
  spec.name          = "my_gem"
  spec.version       = MyGem::VERSION
  spec.authors       = ["Your Name"]
  spec.email         = ["your.email@example.com"]
 
  spec.summary       = "Short summary of gem"
  spec.description   = "Longer description of what gem does"
  spec.homepage      = "https://github.com/username/my_gem"
  spec.license       = "MIT"
 
  spec.required_ruby_version = ">= 3.0.0"
 
  spec.metadata["homepage_uri"] = spec.homepage
  spec.metadata["source_code_uri"] = "https://github.com/username/my_gem"
  spec.metadata["changelog_uri"] = "https://github.com/username/my_gem/CHANGELOG.md"
 
  # Specify which files should be added to the gem
  spec.files = Dir.chdir(File.expand_path(__dir__)) do
    `git ls-files -z`.split("\x0").reject do |f|
      f.match(%r{\A(?:test|spec|features)/})
    end
  end
 
  spec.bindir        = "exe"
  spec.executables   = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
  spec.require_paths = ["lib"]
 
  # Runtime dependencies
  spec.add_dependency "activesupport", "~> 7.0"
  spec.add_dependency "nokogiri", ">= 1.10"
 
  # Development dependencies
  spec.add_development_dependency "rspec", "~> 3.12"
  spec.add_development_dependency "rubocop", "~> 1.50"
end

# lib/my_gem/version.rb
module MyGem
  VERSION = "0.1.0"
end

# lib/my_gem.rb
require_relative "my_gem/version"
require_relative "my_gem/core"
require_relative "my_gem/helpers"
 
module MyGem
  class Error < StandardError; end
 
  def self.configure
    yield configuration
  end
 
  def self.configuration
    @configuration ||= Configuration.new
  end
 
  class Configuration
    attr_accessor :api_key, :timeout
 
    def initialize
      @api_key = nil
      @timeout = 30
    end
  end
end

# Build gem locally
gem build my_gem.gemspec
 
# This creates my_gem-0.1.0.gem
 
# Install locally for testing
gem install ./my_gem-0.1.0.gem
 
# Uninstall
gem uninstall my_gem

# First time setup (one-time)
gem push my_gem-0.1.0.gem
# You'll be prompted to log in
 
# For subsequent pushes
gem push my_gem-0.2.0.gem
 
# Yank a version (removes from RubyGems)
gem yank my_gem -v 0.1.0
 
# Unyank a version
gem unyank my_gem -v 0.1.0

# Semantic Versioning: MAJOR.MINOR.PATCH
# 1.0.0 -> 1.0.1 (patch)
# 1.0.1 -> 1.1.0 (minor)
# 1.1.0 -> 2.0.0 (major)
 
# lib/my_gem/version.rb
module MyGem
  VERSION = "1.0.0"
end
 
# Update version, then build and push:
# 1. Edit version.rb
# 2. gem build my_gem.gemspec
# 3. gem push my_gem-1.0.0.gem

# List installed gems
gem list
 
# Search for gems
gem search rails
 
# Show gem info
gem info rails
 
# List gem dependencies
gem dependency rails
 
# Update all gems
gem update
 
# Update specific gem
gem update rails
 
# Cleanup old versions
gem cleanup
 
# Show gem environment
gem env
 
# Install specific version
gem install rails -v 7.1.0
 
# Install without documentation (faster)
gem install rails --no-document
 
# Uninstall gem
gem uninstall rails
 
# Fetch gem but don't install
gem fetch rails

# Define groups
group :development do
  gem 'pry'
end
 
group :test do
  gem 'rspec'
end
 
group :development, :test do
  gem 'factory_bot'
end
 
# Install without specific groups
bundle install --without production
 
# Require specific groups
Bundler.require(:default, :development)

# Primary source
source 'https://rubygems.org'
 
# Additional sources
source 'https://gems.example.com' do
  gem 'private_gem'
end
 
# Git sources
gem 'my_gem', git: 'https://github.com/user/my_gem.git'
gem 'my_gem', git: 'https://github.com/user/my_gem.git', tag: 'v1.0'
gem 'my_gem', git: 'https://github.com/user/my_gem.git', branch: 'main'
gem 'my_gem', git: 'https://github.com/user/my_gem.git', ref: 'abc123'
 
# GitHub shorthand
gem 'my_gem', github: 'user/my_gem'
 
# Local path
gem 'my_gem', path: '../my_gem'

# In code
require 'my_gem'
 
# Bundler auto-requires gems based on Gemfile
# To disable auto-require:
gem 'my_gem', require: false
 
# Then manually require where needed:
require 'my_gem'
 
# Require specific file
gem 'sidekiq', require: 'sidekiq/web'

# Only install on specific platforms
gem 'pg', platforms: :ruby
gem 'sqlite3', platforms: [:mingw, :mswin, :x64_mingw]
 
# Multiple platforms
platforms :ruby do
  gem 'pg'
  gem 'nokogiri'
end
 
platforms :jruby do
  gem 'activerecord-jdbc-adapter'
end

# Gemfile
source 'https://rubygems.org'
 
source 'https://gems.mycompany.com' do
  gem 'private_gem'
end

# .netrc file for private repos
machine github.com
  login your-username
  password your-token

# Open IRB with gem loaded
bin/console
 
# Or
bundle console

# Using Rake
rake spec
 
# Or directly
bundle exec rspec

# In your app's Gemfile, point to local gem
gem 'my_gem', path: '../my_gem'
 
# Or use bundle config
bundle config local.my_gem ../my_gem

# Clear bundler cache
bundle clean --force
 
# Regenerate Gemfile.lock
rm Gemfile.lock && bundle install
 
# Check for gem conflicts
bundle exec gem dependency
 
# Verbose output
bundle install --verbose
 
# Show why a gem is needed
bundle show rails
 
# List all gem versions
bundle list