class NameError

def missing_name

# => "HelloWorld"
end
e.missing_name
rescue NameError => e
HelloWorld
begin

Extract the name of the missing constant from the exception message.

def missing_name
  # Since ruby v2.3.0 `did_you_mean` gem is loaded by default.
  # It extends NameError#message with spell corrections which are SLOW.
  # We should use original_message message instead.
  message = respond_to?(:original_message) ? original_message : self.message
  if /undefined local variable or method/ !~ message
    $1 if /((::)?([A-Z]\w*)(::[A-Z]\w*)*)$/ =~ message
  end
end

Instance Methods