Re: Import gem to Ruby 1.9

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Hi,

Tanaka Akira wrote:
>> You misunderstand me.  As I wrote in [ruby-core:12810], if it's good way
>> to go, RubyGems team will adopt it.  If RubyGem team won't adopt it, it
>> means that it's not good for RubyGems.  From the very biginning of this
>> thread, I worked for bundling RubyGems as a part of trunk as is.
> 
> I see.  The maintenance problem exists until RubyGems
> developper adopt it.

Sure.  And your LoadError fallback has the same issue.  The hack should
be maintained by RubyGems team because the check scheme depends on
RubyGems specification.  For example, you need to check APPLE_GEM_HOME
in rbconfig if RubyGems team accepts the patch from Apple for Leopard:
http://rubyforge.org/pipermail/rubygems-developers/2007-October/003112.html

According to DRY principle, we should not such logic in prelude.rb.

>> Your proposal don't allow to use others I wrote in [ruby-core:12774] for
>> example, right?  1.9.1 uses rubygems when a LoadError given.
> 
> I understand.  I assumed "other version selection schemes" as
> packaging system provided by OS: dpkg/rpm/ports/pkgsrc/etc.
> But you think it differently.

I see.

> Hmm.  For your loader, we can provide
> disable-rubygems-loader.rb:

> RUBYOPT='-rdisable-rubygems-loader -ryour-favorite-loader'
> disables RubyGems and enables your favorite loader.

I don't like this sort of negative spell.

> On second thought, disable-rubygems-loader.rb may be
> unnecessary.
> 
> My tiny loader or RubyGems causes LoadError.  So simply
> wrapping require method may work.
> 
> Would you show me a loader which doesn't work well with my
> loader?

module Kernel
  alias foo_hooked_require require

  def require(feature)
    begin
      foo_hooked_require feature
    rescue LoadError => e
      p "do something good"
      require feature
    end
  end
end

With RUBYOPT=-rfooloader, we can hook Kernel#require before RubyGems is
activated.  The require chain after a LoadError is as follows.

  rubygems -> foo -> rubygemsloader -> original_require

So foo can intercept a LoadError from rubygems.  But when an user
activates a gem with rubygems, say rails, dependency libraries are
activated by rubygems, too.  Now foo cannot intercept LoadError for
these libraries.

Till ruby equips sophisticated feature loading extension point, mixing
two or more loaders should not be expected to work.  Incorporating your
LoadError fallback means that Ruby allows RubyGems to be used as a only
custom loader.  I hope I can explain myself well.

Regards,
// NaHi

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