From: Joel VanderWerf <vjoel@...>
Date: 2009-08-21T02:12:25+09:00
Subject: Re: crown 1.0.0

Ryan Davis wrote:
> 
> On Aug 20, 2009, at 01:17 , Brian Candler wrote:
>> I guess the downside is, you can't have multiple versions of the same
>> gem available at once?
>>
>> I guess if each application or project has its own tree of symlinks or
>> copies of the gems, that's fine.
> 
> That's exactly the point of crown as I see it.

Right. It would be a problem if, for example, your project contains two 
executables which depend on different gem versions. Crown barfs if you 
include two versions of the same gem.[1]

Currently, I'm using this to give production and development trees their 
own gem environments that don't change when gem update happens. At well 
defined intervals, we can re-crown development to pull in the latest 
gems. When it's time to migrate dev to pro, we just pull the crown along 
with it.

This would also be possible by specifying gem versions explicitly in the 
source, but that seems harder to automate. Also, by not using rubygems' 
require we can be sure that there are no unmanaged dependencies.

[1]
$ crown cr narray=0.5.9.7 narray=0.5.9.6
Replication target for 
/usr/local/lib/ruby/gems/1.8/gems/narray-0.5.9.6/./src/ChangeLog exists 
and is different: cr/./src/ChangeLog

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407