Exception: NameError

StandardError show all
Defined in:


Raised when a given name is invalid or undefined.

puts foo

raises the exception:

NameError: undefined local variable or method `foo' for main:Object

Since constant names must start with a capital:

Fixnum.const_set :answer, 42

raises the exception:

NameError: wrong constant name answer

Direct Known Subclasses


Defined Under Namespace

Classes: message

Instance Method Summary collapse

Methods inherited from Exception

#==, #backtrace, #exception, exception, #inspect, #message, #set_backtrace

Constructor Details

#new(msg[, name]) ⇒ Object

Construct a new NameError exception. If given the name parameter may subsequently be examined using the NameError.name method.

# File 'error.c'

static VALUE
name_err_initialize(int argc, VALUE *argv, VALUE self)
    VALUE name;

    name = (argc > 1) ? argv[--argc] : Qnil;
    rb_call_super(argc, argv);
    rb_iv_set(self, "name", name);
    return self;

Instance Method Details


Return the name associated with this NameError exception.


# File 'error.c'

static VALUE
name_err_name(VALUE self)
    return rb_attr_get(self, rb_intern("name"));


Produce a nicely-formatted string representing the NameError.


# File 'error.c'

static VALUE
name_err_to_s(VALUE exc)
VALUE mesg = rb_attr_get(exc, rb_intern("mesg"));
VALUE str = mesg;

if (NIL_P(mesg)) return rb_class_name(CLASS_OF(exc));
if (str != mesg) {
rb_iv_set(exc, "mesg", mesg = str);