From: ara.t.howard@...
Date: 2006-03-26T00:42:34+09:00
Subject: Re: require a certain version of the ruby interpreter

On Sun, 26 Mar 2006 dblack@wobblini.net wrote:

>> my point is that this code does not 'ensure' version 1.8.4 - it blows up 
>> unless
>> version 1.8.x.
>
> I think you've discovered Duck Versioning:
>
>  [].zip([]) rescue NameError "You need a later Ruby"
>
> :-)

you may be joking but this is really good!

   harp:~ > cat a.rb
   "1.8.4".respond_to?("any?") or raise "require 1.8.4"
   [].inject([])

   harp:~ > ruby184 a.rb

   harp:~ > ruby168 a.rb
   a.rb:1: require 1.8.4 (RuntimeError)

one simply needs to select a single method that exists starting in the required
version.

regards.

-a
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