From: Rob Biedenharn <Rob@...>
Date: 2009-11-11T11:43:43+09:00
Subject: Re: Roman Numerals (Arrgh!)

On Nov 10, 2009, at 8:49 PM, Gennady Bystritsky wrote:

> On Nov 10, 2009, at 5:37 PM, Rob Biedenharn wrote:
>
>> On Nov 10, 2009, at 6:56 PM, Rick Barrett wrote:
>>
>>> I have a homework assignment where I have to convert an inputted
>>> integer
>>> into Roman Numerals. I was doing fine building upon the previous  
>>> steps
>>>
>>
>> P.S. I saw Gennady's post, but I'd argue that no one would really  
>> want
>> to solve the problem that way. And Nik's way doesn't give any help
>
> Why not that way? It works and it is short ;-)
>
> Gennady.

Not that it doesn't work, just that it might be easier/quicker to  
rewrite than to understand. Short isn't *always* a virtue and if  
there's a reason (performance?) to be terse, then there ought to be a  
comment by way of explanation.

There are few truly necessary uses of Enumerable#inject and this isn't  
one of them, but if it were, I'd make it at least slightly more  
readable:

   def roman_numeral(number)
     $numerals.inject(["", number]) { |(answer, number), (arabic,  
roman)|
       [ answer + roman * (number / arabic), number % arabic ]
     }.first
   end

And with an appropriately formed $numerals array, the "subtraction  
rule" is already covered. ;-)

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob@AgileConsultingLLC.com