From: Charles Mills <cmills@...>
Date: 2004-06-14T01:20:16+09:00
Subject: String#==

String#== returns nil when the object being compared does not have a 
"to_str" method.
For example:
irb> "hey" == 1
=> nil
Is that correct?
Here is the code (from 1.8.1):
/* taken from string.c line 792 */
static VALUE
rb_str_equal(str1, str2)
     VALUE str1, str2;
{
     if (str1 == str2) return Qtrue;
     if (TYPE(str2) != T_STRING) {
   if (!rb_respond_to(str2, rb_intern("to_str"))) {
       return Qnil;
   }
   return rb_equal(str2, str1);
     }
     if (RSTRING(str1)->len == RSTRING(str2)->len &&
   rb_str_cmp(str1, str2) == 0) {
   return Qtrue;
     }
     return Qfalse;
}
/* ... snip ... */
      rb_define_method(rb_cString, "==", rb_str_equal, 1);
/* end */

-Charlie