From: Nikolai Weibull <now@...>
Date: 2009-10-22T17:25:09+09:00
Subject: [ruby-core:26226] Re: Config.datadir in 1.9.1

On Thu, Oct 22, 2009 at 04:55, Yugui <yugui@yugui.jp> wrote:

> 2009/10/21 Nikolai Weibull <now@bitwi.se>:

>> In 1.8.6., Config.datadir('package') would give you the gem-relative
>> data directory for a gem. ��In 1.9.1, Config doesn���t seem to even be
>> loaded at startup. ��What happened? ��What am I supposed to use instead?
>> ��Even if you get Config loaded it still won���t work, as the gem���s paths
>> are already added to $LOAD_PATH, so Rubygems won���t load the
>> specification and thus Gem.datadir('package') will give a nil result.

> First, ::Config is deprecated. You should use RbConfig instead.
> ::Config is an alias of RbConfig for compatibility to < 1.8.
>
> Second, RbConfig is a bundled library but not a core library. So it is
> not loaded by default.
> I think it has been loaded by RubyGems when you use RubyGems.
>
> Third, RbConfig.datadir(pkg) is a part of RubyGems but not a part of RbConfig.
>
> So you should write like this:
>
> ��require 'rbconfig'
> ��require 'rbconfig/datadir'
>
> ��RbConfig.datadir("blahblahblah")
>
> This works fine for both 1.8 and 1.9.

Well, actually it doesn���t work.  I mean, yes, the function is there,
but the problem is that it doesn���t return the correct path.  Let me
clear this up a bit.  Assume that expectations-1.2.1 is installed for
both 1.8 and 1.9.1.

In 1.8.6, with RUBYOPT="-rubygems", I could simply start up irb and
the following would happen:

% irb
irb(main):001:0> require 'expectations'
=> true
irb(main):002:0> Config.datadir('expectations')
=> "C:/Ruby18/lib/ruby/gems/1.8/gems/expectations-1.2.1/data/expectations"

but on 1.9.1 that isn���t as straightforward.  Fine, we���ll do the
following instead:

% irb
irb(main):001:0> require 'expectations'
=> true
irb(main):002:0> require 'rbconfig'
=> true
irb(main):003:0> require 'rbconfig/datadir'
=> true
irb(main):004:0> RbConfig.datadir('expectations')
=> "C:/Ruby19/share/expectations"

OK, so Rubygems isn���t loaded automatically and can thus not override
RbConfig.datadir.  What we need to do seems to be

% irb
irb(main):001:0> require 'expectations'
=> true
irb(main):002:0> Gem.datadir('expectations')
=> nil
irb(main):003:0> gem 'expectations'
=> true
irb(main):004:0> RbConfig.datadir('expectations')
=> "C:/Ruby19/lib/ruby/gems/1.9.1/gems/expectations-1.2.1/data/expectations"

and that, my friends, is insane.  The Gem.datadir('expectations')
seems to be needed to get the gem 'expectations' to actually do
anything (it returns false if the Gem.datadir('expectations') doesn���t
appear before it).  I���m guessing that that line loads up Rubygems,
because a require 'rubygems' sure doesn���t.

So instead of Rubygems being transparently integrated into Ruby 1.9.1,
what I���ve got now is an incredible mess where I need to force Rubygems
to rear its ugly head all over the place.