ruby_select experimental implementation

[kimura wataru]

Hi,

I write experimental ruby_select for ruby186 and ruby18.

  http://trac.macports.org/browser/users/kimuraw/ruby_select

== install destinations

* different name for ruby bundled commands and libraries 
* share library and document directory for additional libraries

this allows to activate both of ruby186 and ruby18.


 dir,file       1.8.6(ruby186)             1.8.7(ruby18) 
------------------------------------------------------------
bin/ruby        bin/ruby186                bin/ruby18 
bin/irb         bin/irb186                 bin/irb18 
  :
libdir          lib/ruby/1.8.6/            lib/ruby/1.8.7/ 
sitedir         lib/ruby/site_ruby/1.8/    (share) 
vendordir       lib/ruby/vendor_ruby/1.8/  (share) 
libruby.so      libruby186.dylib           libruby18.dylib 
ri sysdir       share/ri/1.8/system1.8.6/  share/ri/1.8/system1.8.7/ 
ri sitedir      share/ri/1.8/site/         (share) 
------------------------------------------------------------

macports' vendor-specific.rb and site-specific.rb are moved
to lidir from vendordir and sitedir to avoid conflicts.

== ruby_select

sysutils/ruby_select uses same tool as port:python_select or port:gcc_selct.

  % sudo ruby_select ruby18
  Selecting version "ruby18" for ruby
  % ls -l /opt/local/bin/ruby
  lrwxr-xr-x  1 root  admin  21 Apr 18 21:03 /opt/local/bin/ruby@ -> /opt/local/bin/ruby18
  % sudo ruby_select ruby186
  Selecting version "ruby186" for ruby
  % ls -l /opt/local/bin/ruby
  lrwxr-xr-x  1 root  admin  22 Apr 18 21:06 /opt/local/bin/ruby@ -> /opt/local/bin/ruby186

the following files are targets of ruby_select.
* bin/ ruby, erb, irb, rdoc, ri, testrb
* lib/ libruby.dylib, libruby-static.a

ruby_select make symlinks the above files at post-activate. 
then, install ruby_select means existence of ${prefix}/bin/ruby (without suffix).
I expect this port become a meta port port:ruby.

== linking libruby

ruby_select introduce libruby.dylib. this file is a symbolic link for 
libruby186.dylib or libruby18.dylib. and, vendor-specific.rb changes 
LIBRUBYARG and so on.

  % ruby -rrbconfig -e 'p Config::CONFIG["LIBRUBYARG"]'        
  "-lruby18"
  % ruby -rvendor-specific -rrbconfig -e 'p Config::CONFIG["LIBRUBYARG"]'
  "-lruby"

so, port:rb-* links libruby.dylib and extension modules (.bundle)
use ruby_select-ed libruby.

this implementation is not enough. please tell me your thoughts.

-- 
kimura wataru