From: Bertram Scharpf <lists@...>
Date: 2007-10-22T17:19:00+09:00
Subject: Re: How does overload work in ruby?

Hi,

Am Montag, 22. Okt 2007, 14:25:49 +0900 schrieb Xavier Noria:
> On Oct 22, 2007, at 7:17 AM, Shuaib Zahda wrote:
>> is there any special way for overloading in ruby.
>>
>> class Overloading
>>
>>  def sum(a, b)
>>   return a + b
>>  end
>>
>>  def sum(a, b, c)
>>   return a + b + c
>>  end
>
> Ruby does not support method overloading that way. [...]
> However, you can define defaults 
> for optional parameters like this:
>
>   def sum(a, b, c=0)
>     a + b + c
>   end

If you want to allow the caller to select the default value
explicitly you may say

  def sum a, b, c = nil
    c ||= 0
    a + b + c
  end

Some methods even change their behaviour with the number of
parameters they are called with, for example File#basename.
You still may check whether the last parameter is nil. If
you need to be 100% sure, you could write a C function;
rb_scan_args() returns the number of arguments given.

Bertram


-- 
Bertram Scharpf
Stuttgart, Deutschland/Germany
http://www.bertram-scharpf.de