Module Import

Namespace all imported modules rather than polluting the global namespace.

This is an investigation into different ways of loading modules inspired by the Node.js Module loading system.

When a file is loaded, the result is encapsulated inside a module, and the desired module/class is exported as EXPORTS and returned from the function.

Benefits

Better encapsulation, there are reduced side effects from importing modules.

You can load two different versions of the same module without having them clash in the global namespace.

Drawbacks

It's slower, we're using eval which is pretty slow.

Doesn't work with existing libraries. it's not a replacement for require but can be used along side it.

Likely won't work with C extensions.

Example

Given a module in file line.rb, where the Line module is set as EXPORTS:

module Line
  def Line.check
    puts 'Line check'
  end
end

EXPORTS = Line

This can be imported using ModuleImport.import:

LineModule = ModuleImport.import('./other_line.rb')
    
LineModule.check

Alternatives

Unsurprisingly, I'm not the first person to have this idea, @soveran had a similar idea a few years ago: https://github.com/soveran/cargo/

The implementation is a bit cleaner, it uses Kernel.load which loads the file completely seperately and returns only the exported module.

TODO

• Load paths in a similar way to require, searching load paths etc
• Caching of loaded modules
• Tests
• More Examples
• Publish as a rubygem
• Investigate importing on a thread to force seperation (using Marshal for passing EXPORTS back)

Development

Source hosted at GitHub. Report Issues/Feature requests on GitHub Issues.

Tests can be ran with rake spec

Note on Patches/Pull Requests

• Fork the project.
• Make your feature addition or bug fix.
• Add tests for it. This is important so I don't break it in a future version unintentionally.
• Add documentation if necessary.
• Commit, do not mess with rakefile, version, or history. (if you want to have your own version, that is fine but bump version in a commit by itself I can ignore when I pull)
• Send a pull request. Bonus points for topic branches.

Copyright

Copyright (c) 2013 Andrew Nesbitt. See LICENSE for details.