In response to https://www.ruby-forum.com/topic/4422634

arup_meth_var.rb

#!/usr/bin/env ruby

# If no local variable is found,
# it begins the method lookup that ends calling 
# the method_missing chain until the last one raises the error

begin
  p undefined_name if true
rescue 
  puts "Raised an error"
else
  puts "No error at all"
end

def method_missing(method, *args)
  "I'm a method"
end

# When no method is found, 
# It hits the method_missing and do what is defined on it
# so... returns "I'm a method" without raising any errors.

puts

begin
  p undefined_name if true
rescue 
  puts "Raised an error"
else
  puts "No error at all"
end

undefined_name = "I'm a local-variable" 

# Now a local-variable with the same name is found (before the method)

puts

begin
  p undefined_name if true
rescue 
  puts "Raised an error"
else
  puts "No error at all"
end

# If we need to disambiguate it, for the method we need to prepend the object will be sending it to.
# self.undefined_name vs. undefined_name

puts

begin
  p self.undefined_name if true
rescue 
  puts "Raised an error"
else
  puts "No error at all"
end