Quick Answer

Fix missing constant references.

Understanding the Issue

This error occurs when Ruby cannot find a class, module, or other constant. Common causes include typos, missing requires, or incorrect scoping.

The Problem

This code demonstrates the issue:

Ruby Error 
Person.new # NameError if Person undefined

The Solution

Here's the corrected code:

Ruby Fixed 
# Solution 1: Require needed files
require "person"

# Solution 2: Check class existence
if defined?(Person)
  Person.new
end

# Solution 3: Absolute namespace reference
::Person.new # From root namespace

# Solution 4: Autoloading (Rails)
# config/initializers/autoload.rb
# Rails.autoloaders.each do |autoloader|
#   autoloader.preload "app/models/person.rb"
# end

Key Takeaways

Ensure proper file loading and namespace resolution.