 class NameError 

Parent:
Object
    Public Instance Methods    missing_name() Show source  
 # File activesupport/lib/active_support/core_ext/name_error.rb, line 12
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
    $1 if /((8b7c:f320:99b9:690f:4595:cd17:293a:c069)?([A-Z]\w*)(8b7c:f320:99b9:690f:4595:cd17:293a:c069[A-Z]\w*)*)$/ =~ message
  end
end  Extract the name of the missing constant from the exception message. begin
  HelloWorld
rescue NameError => e
  e.missing_name
end
# => "HelloWorld"
     missing_name?(name) Show source  
 # File activesupport/lib/active_support/core_ext/name_error.rb, line 31
def missing_name?(name)
  if name.is_a? Symbol
    self.name == name
  else
    missing_name == name.to_s
  end
end  Was this exception raised because the given name was missing? begin
  HelloWorld
rescue NameError => e
  e.missing_name?("HelloWorld")
end
# => true
    

    
{'path': 'public/docs/rails~6.0/nameerror.html', 'source': 'DevDocs.IO'}