Bundler.setup vs. Bundler.require
There are two ways to use Bundler to require Ruby dependencies: manually with Bundler.setup and automatically with Bundler.require.
Bundler.setup only sets up the load paths so that you can require your dependencies when and wherever you like.
# Gemfile
source "https://rubygems.org"
gem "sinatra"
gem "http"
# environment.rb
require "bundler"
Bundler.setup(:default)
require "sinatra/base"
require "http"Bundler.require sets up the load paths and automatically requires every dependency, saving you from having to manually require each one.
# Gemfile
source "https://rubygems.org"
gem "sinatra", require: "sinatra/base"
gem "http"
# environment.rb
require "bundler"
Bundler.require(:default)Bundler.setup and Bundler.require also take multiple gem groups as arguments, allowing you to conditionally load groups based on the environment.
# Gemfile
source "https://rubygems.org"
gem "sinatra", require: "sinatra/base"
gem "http"
gem "pry", group: "development"
gem "thin", group: "production"
# environment.rb
require "bundler"
Bundler.require(:default, ENV["RACK_ENV"].to_sym)