Misc #12835: RDoc comment of String#casecmp

• Status: Closed
• Assignee: -

[dogatana (Toshihiko Ichida)]

String#casecmp dose not return nil but raise TypError for incomparable argument.

So

 *     str.casecmp(other_str)   -> -1, 0, +1 or nil

should be like

 *     str.casecmp(other_str)   -> -1, 0, +1

or

 *     str.casecmp(other_str)   -> -1, 0, +1 or raise TypeError if other_str is not comparable

Here is a example.

irb(main):001:0> "a" <=> 1                               
=> nil                                                   
irb(main):002:0> "a".casecmp(1)                          
TypeError: no implicit conversion of Fixnum into String  

Japanese Reference Manual has same issue.

[znz (Kazuhiro NISHIYAMA)]

I created pull request for Japanese Reference Manual.

[stomar (Marcus Stollsteimer)]

Note that String#casecmp can return nil:

"\u{e4 f6 fc}".encode("ISO-8859-1").casecmp("\u{c4 d6 dc}")   #=> nil

The relevant lines in the source code (in string.c):

static VALUE
rb_str_casecmp(VALUE str1, VALUE str2)
{
    /* ... */

    enc = rb_enc_compatible(str1, str2);
    if (!enc) {
        return Qnil;
    }

    /* ... */
}

[stomar (Marcus Stollsteimer)]

I tried to clarify this in the rdoc with r57886.

[stomar (Marcus Stollsteimer)]

• Status changed from Open to Closed

Closing since the rdoc matches the actual behavior. Additionally I opened a new issue because raising TypeError seems to be inconsistent with other comparison methods, see #13312.