From: Xavier Noria <fxn@...>
Date: 2010-07-21T20:20:40+09:00
Subject: Re: How to check if x is a multiple of y

On Wednesday, July 21, 2010, Robert Klemme <shortcutter@googlemail.com> wrote:
> 2010/7/21 Xavier Noria <fxn@hashref.com>:
>> On Wed, Jul 21, 2010 at 12:12 PM, Tom Ha <tom999@gmx.net> wrote:
>>
>>> what's the most simple solution in Ruby to check if value x is a
>>> multiple of y?
>>
>> That's typically done with the modulus operator, Active Support
>> defines it this way
>>
>>    class Integer
>>      # Check whether the integer is evenly divisible by the argument.
>>      def multiple_of?(number)
>>        number != 0 ? self % number == 0 : zero?
>>      end
>>    end
>>
>> It is special-cased because you can't do modulus 0.
>
> I see a benchmark lurking: that version vs. this one.
>
> class Integer
>   def multiple_off? number
>     zero? || self % number == 0
>   end
> end
>
> :-)

But that one is not well-defined for 1.multiple_of?(0) :-)