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rubyrubygemsrequire

`require` vs. `gem` methods?

What's the difference between the require and gem methods?

For example, what's the difference betweenrequire 'minitest' and gem 'minitest'?

Solution

  • Say you have two versions of the gem foo installed:

    $ gem list foo

*** LOCAL GEMS ***

foo (2.0.1, 2.0.0)

    If you use only require, the newest version will be loaded by default:

    require 'foo'       # => true

Foo::VERSION        # => "2.0.1"

    If you use gem before calling require, you can specify a different version to use:

    gem 'foo', '2.0.0'  # => true
require 'foo'       # => true

Foo::VERSION        # => "2.0.0"

    Note: using gem without subsequently calling require does not load the gem.

    gem 'foo'           # => true

Foo::VERSION        # => NameError: uninitialized constant Foo