Forum: Ruby Cross-platform gems / conditional loading of gems

Hi all,

We use ruby as part of our development team tools for Windows and Mac 
machines.  This is maintained internally in an SVN repository where the 
platform-specific files are interleaved, i.e. the bin/ directory 
contains both a Windows ruby.exe and a Mac ruby executable.  This 
repository is packaged into installers so we can deploy to our dev team 
ensuring that everyone has the correct ruby version and gems.

New gems are installed on an administrator's machine and SVN added to 
the gems folder (and the corresponding gemspec is added to the 
specifications folder).  Most of these are platform agnostic but we have 
a few that are Windows-only, e.g. qtbindings.

This was working fine until trying to get sqlite3 running on both PC and 
Mac.  The PC version was installed first 
(gems/sqlite3-1.3.6-x86-mingw32) and this worked fine.  The mingw32 
version is PC only so I installed sqlite3 on an OSX machine which added 
the new gem to gems\sqlite3-1.3.6.

This new gem conflicts with the PC version, e.g. attempting to require 
via IRB on the Mac:

irb(main):001:0> require 'sqlite3'
LoadError: cannot load such file -- sqlite3/sqlite3_native
                from 
/Users/aallmont/nm/buildtools/ruby/1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in 
`require'
                from 
/Users/aallmont/nm/buildtools/ruby/1.9.3/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in 
`require'

This error goes away if I remove the gems/sqlite3-1.3.6-x86-mingw32 
folder on the Mac.  There is a similar error on the PC which goes away 
if I remove the gems/sqlite3-1.3.6-x86 folder, i.e. they are mutually 
exclusive.

I would like to only load gems/sqlite3-1.3.6-x86 when running on the Mac 
and only load gems/sqlite3-1.3.6-x86-mingw32 when running on the PC.  Is 
this possible?

Many thanks,
Alex

Try something like:

    if RUBY_PLATFORM =~ /(win|ming)/
      ...
    else
      ...
    end

In my config/database.yml I have the following:

development:
   adapter: <%= "jdbc" if defined?(JRUBY_PLATFORM) %>sqlite3
   database: db/dtf_development.sqlite3
   pool: 5
   timeout: 5000


In my spec/spec_helper I have the following (Need to change the YAML
engine used under JRuby):

# Set the YAML engine for JRuby
if RUBY_PLATFORM == "java"
   ::YAML::ENGINE.yamler = 'psych'
end

When working with gems (as in writing them) use this in your gemspec for
specifying a specific sqlite3 based on the platform:

   gem.add_dependency "sqlite3" if RUBY_PLATFORM == "ruby"

   gem.add_dependency "jdbc-sqlite3" if RUBY_PLATFORM == "java"
   #gem.add_dependency "activerecord-jdbcsqlite3-adapter" if
RUBY_PLATFORM == "java"
   gem.add_dependency "jruby-openssl" if RUBY_PLATFORM == "java"


In these instances, I am adapting to change for use with JRuby. Modify
as you need for the Windows platform.


>
> team ensuring that everyone has the correct ruby version and gems.
> added the new gem to gems\sqlite3-1.3.6.
> `require'
> I would like to only load gems/sqlite3-1.3.6-x86 when running on the
> Mac and only load gems/sqlite3-1.3.6-x86-mingw32 when running on the
> PC.  Is this possible?
>
> Many thanks,
>
> Alex
>

--
D. Deryl Downey

"The bug which you would fright me with I seek" - William Shakespeare - 
The Winter's Tale, Act III, Scene II - A court of Justice.