Descendents of class Exception are used to communicate between raise methods and rescue statements in begin/end blocks. Exception objects carry information about the exception—its type (the exception’s class name), an optional descriptive string, and optional traceback information. Programs may subclass Exception to add additional information.

Methods
N
T
Classes and Modules
Class Public methods
NameError.new(msg [, name]) => name_error

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

Source: show 

static VALUE
name_err_initialize(argc, argv, self)
    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 Public methods
name_error.name => string or nil

Return the name associated with this NameError exception.

Source: show 

static VALUE
name_err_name(self)
    VALUE self;
{
    return rb_attr_get(self, rb_intern("name"));
}
name_error.to_s => string

Produce a nicely-formated string representing the NameError.

Source: show 

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

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