CODEWITHSUNDEEP
rubyrubygemsrequire
Leo
Leo

Reputation: 583

When is the 'require' necessary when using a ruby gem?

I noticed for some gems you must include it in the file where you want to use it like this require 'a_gem', but this is not always the case.

I am going to compose a gem by myself. What should I do if I do not want to add the require 'my_gem' to the .rb file when using it?

Upvotes: 5

Views: 2073

Answers (2)

Eric Duminil
Eric Duminil

Reputation: 54213

This doesn't make sense. If you want to write a Gem and use it, it needs to be required somewhere.

This "somewhere" could be explicit in one of your scripts, it could be written in a Gemfile or it could be required by another script/gem that is required by your script.

If you write a gem, Ruby will not include it automatically in all your scripts.

Finally, if you publish it, should every single Ruby script on earth magically require it and execute your code?

I suppose that the project you have seen which didn't use require 'a_gem' was using a Gemfile.

Upvotes: 0

Wayne Conrad
Wayne Conrad

Reputation: 107959

Usually, an application that is using a gem needs to require the gem:

require "my_awesome_gem"
MyAwesomeGem.do_something_great

However, if an application is using bundler, which defines the application's gem in a file called "Gemfile":

source 'http://rubygems.org'
gem 'my_awesome_gem'

then the application may invoke bundler in a way that automatically requires all of the gems specified in the Gemfile:

require "bundler"
Bundler.require
MyAwesomeGem.do_something_great

Rails projects use Bundler.require, so a Rails application will not need to explicitly require a gem in order to use it: Just add the gem to the Gemfile and go.

For more about Bundler.require, see the bundler documentation

For more about how Rails uses Bundler, see How Does Rails Handle Gems? by Justin Weiss.

Upvotes: 10

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