Managing gem versions/dependencies for Rails

Just a bit of background, I come from a strong C#/staticly typed background. Therefore I tend to think in terms of .dlls. So if I was working in a project, I'd reference my required dlls and that would be that.

Being new to Ru开发者_运维知识库by and Rails I find I might be doing something wrong. For example, I create a Rails app at home using the gems I have locally. Using a different computer (say a work computer) I attempt to work on the project only to find I'm using different versions of the gems. After carrying out a bundle install I'm back to a working project.

The issue I have with this is that my gem library becomes 'messy'. I end up with several versions of the same gem. Is this the way others work? When using a gem (from a require) will it default to the latest version? I feel as if I'm not managing the dependencies correctly, though as I've mentioned I'm new to the world of Ruby.

Should I just include my dependencies, then perform a bundle install each time I have different/missing dependencies? What happens if I wish to upgrade to a newer version of a gem? Would it be a case of updating the gemfile that bundle uses and getting on with it?

Yes, bundler is the way to go to work with dependancies with Ruby on Rails. Why ? First, because it's shipped with it (at least for version 3.0). Second, because it's simple as hell (unlike maven with Java).

A non exhaustive list of feature :

• it lets you declare one or many gem repository to fetch gems from
• to group your dependencies by environment (development, production...)
• to specify version you'd like

and so on. For more on this, check this http://gembundler.com/rationale.html

Regarding your question : yes, bundler will take the latest version available is none is specified.

Also, I would add a disavantage : you cannot specify a gem version depending on the OS. For example, nokogiri has a linux version AND a win version.

The default behaviour when requiring a module in a gem is to assume you want the latest version of the gem if you have more than one installed. You can change this by specifying which version you want in a specific application like this:

gem "rails", "2.3.8"

Before you require anything from the gem. This ensures that this application will use the specified version of the gem, even if a newer one is installed.

You can of course clean out obsolete versions of your installed gems whenever you don't need them again, or if you use bundler consistently: just wipe everything and run bundler again to get just your required gems installed.

Another useful tool is the Ruby Version Manager (RVM), in addition to handling different versions of ruby it provides a feature called gemsets which allows you to isolate different applications or environments from eachother. That is App A can have its separate gemset with all its required gems, and App B have another gemset with only its required gems. This will reduce the clutter in your dependencies quite a bit.