From: ptkwt@...1.aracnet.com (Phil Tomson)
Date: 2003-01-03T07:31:43+09:00
Subject: Re: Compatibility (was Class.inherited)

In article <1041521908.14269.30.camel@zip>,
Dave Thomas  <dave@thomases.com> wrote:
>On Thu, 2003-01-02 at 08:48, Yukihiro Matsumoto wrote:
>
>> I'd like to hear about when, where, what names are suitable for
>> class/method definition hook methods, in addition to above methods?
>> Timing of existing hook might be changed after the discussion.
>
>This raises a somewhat bigger question.
>
>I've now got a fair amount (probably 50kloc) of Ruby in production. Most
>of this runs on 1.6.7. I'm frankly nervous about upgrading it to 1.8
>because of the various changes in the language. Particularly worrying
>are changes where some syntax is valid in both the old and new Ruby, but
>the semantics are different. The .inherited change that sparked this
>thread is one example, changes in precedence in rescue andling is
>another. I've noted others that have passed by on the list.
>
>As Ruby moves from being a hobby language into something that people use
>to write serious production code, I'm wondering if we need to stop and
>consider the implications of incompatibilities such as these. We could
>give ourselves a serious black eye if we were to ship a new release of
>Ruby that stopped some major and publically visible application from
>working.
>
>As a starting point for discussion: how hard would it be to make it a
>rule that all incompatible changes are introduced in two phases. In the
>first, the interpreter would announce that the behavior will change, and
>then in the second (say 3 months later) the change will be introduced.
>That would allow us to run our existing code against the interim
>release, and give us time to fix things up before the change is made.
>

And, if changes must be made that break code perhaps we should offer 
compatibility modules, something like:

#Say I'm running 1.8, but I want it to act like 1.6*:
require 'ruby_1.6'


....or some similar mechanism. 
Or, what about a command line option?

Phil
-- 
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