From: Florian Frank <flori@...>
Date: 2009-10-03T16:46:54+09:00
Subject: Re: Having a gem for 1.8 and 1.9

(RK) Sentinel wrote:
> Rick Denatale wrote:
>   
>> 1.8 vs 1.9 because of the differences in Strings, but I've been able
>> to conditionally select which implementation of a few methods get
>> "compiled" by testing the ruby version inline.
>>
>> --
>> Rick DeNatale
>>     
>
> Could you give me a snippet of your conditional selection ?
>   
Here's a small example:

http://github.com/flori/bullshit/blob/master/lib/bullshit.rb#L716

The code defines a log_gamma function: In 1.8 it uses its own Lanczos 
approximation algorithm written in Ruby. In 1.9 Math already defines an 
lgamma method with a complex result and a C-implementation which is used 
instead if the lgamma method is defined there. If possible it's better 
to check for features you want to use from a specicific Ruby version 
instead of checking for the version itself. This way you are prepared if 
things change or features are eventually backported from Ruby 1.9.

-- 
Florian Frank