From: Csaba Henk <csaba@..._for_avoiding_spam.org>
Date: 2005-03-18T07:34:56+09:00
Subject: encapsulating rubygems so that my users don't need to be aware of it

Hi!

Say in appfoo I use lib_a, lib_b and lib_c.

I know if you want to use appfoo, and you have some of these libs as
gems, you can do it by inserting a "require rubygems" to the beginning
of appfoo, or running it as "ruby -rubygems <path-to-appfoo>", or by
tinkering with $RUBYOPTS.

But what if now I say *I* am aware of rubygems, and I want to let my users
not to care about whether this or that is installed as a gem or not?

One I could come up with is the following: I start apfoo like this:

 %w(lib_a lib_b lib_c).each {|lib|
   begin
     require lib
   rescue LoadError
     require rubygems
     require lib
   end
 }

-- but it's ugly, and gives a useless error message if both rubygems and
one of the libs is missing.

I also tought of 

 begin
   require rubygems
 rescue LoadError
 end
 require lib_a
 require lib_b
 require lib_c

but it pulls in rubygems unnecessarily if it's installed, but lib_* are
not gems.

The following monster:

 %w(lib_a lib_b lib_c).each {|lib|
   begin
     require lib
   rescue LoadError
     begin
       require rubygems
     rescue LoadError
     end 
     require lib
   end
 }

should work like a charm, but it's ridiculously baroque.

Any better idea?

Csaba