From: Gavin Sinclair <gsinclair@...>
Date: 2004-10-05T09:52:31+09:00
Subject: Re: RubyGems and RPA

On Tuesday, October 5, 2004, 9:30:39 AM, James wrote:

> Having just read the RubyGems chapter in the Pickaxe II, I'm curious
> about how it compares to RPA.  I'm not trying to start a war here, but
> I would like some information about their differences, if someone would
> be so helpful.

> Do they solve the same problem, or am I confused?

Same problem: management of Ruby libraries and applications.  Install,
uninstall, and query.

  gem install rake

  rpa install rake

Pretty similar.

> Are there differences in their design philosophy or fundamental
> differences in their operation?

Yes.  RubyGems puts each gem (package) in its own directory, rather
than installing everything into site_ruby/1.8/.  This is specifically
designed so that you can have multiple versions installed, and take
advantage of that to ensure dependencies are met.  For example, one
person on this list was using ActiveRecord, but could only use an old
one because of threading issues with the current release.  So...

  require_gem 'activerecord', '= 0.7.4'

Meant that his code would _only_ work if ActiveRecord v0.7.4 was
installed as a gem on the user's computer.

RPA is more transparent -- installs go into site_ruby and you access
them like any directly-installed package.  It's got some other magic
going on, which escapes me at the moment.

With RubyGems, we try to make it as easy as possible, but the ability
to install and use multiple versions of packages puts a limit on the
transparency.

> Do they offer a similar range of packages?

Yes.  It's RPA's 120 to RubyGems's 100 at the moment, with significant
overlap.

> Can both be installed and peacefully coexist?

Yes.  That should always be the case.

> Any thing else I should know about either?

The main point of RPA is quality control.  It's a "Production
Archive".  Eventually there will be "RPA versions" so you can access a
suite of libraries all tested to work together.  It's centrally
managed.

RubyGems is a decentralised package manager that treats each gem (and
each version of each gem) as independent.  If you have a RubyForge
project, you just "release" your .gem file there, and it will go into
the repository.

> Again, I'm not trying to start a fight, I'm just trying to learn more
> about my options.  Thanks.

No worries.  Hope you enjoy them.  We're lucky to have two package
managers when a year ago we had none.  Both were borne of the
frustration of going years without one, I guess.

Gavin