Ruby Project VS Ruby Gem

Question

I have read through Q&A/articles that explain the ideal structure of a Ruby project. I read the RubyGems guides on how to create a Ruby gem. I have just read a Q&A asking at what point a ruby project becomes a ruby gem but I can not for the life of me see the difference between the two. The structure seems to be the same. The files, where they go, everything looks the same to me. Is it how they're used? Can someone please explain the difference between the two to me?

Answer 1

The question that must be answered respect to 'Gemify' or not is: am I writing something that is readily reusable in a different context? If the answer is yes then your application is a candidate for 'Gemification'. If not then generally it is not worth the additional complexity to convert a Ruby project into a Gem.

For example. If one makes a CLI Ruby application that collects mortgage rates from multiple vendors and updates a database then there are two ways this could be converted into a gem.

First: You could generalise the interface/configuration and make it useful as a plugin/add-on/extension to projects written by someone needing the same or similar functionality. So someone could add the gemified version to their project and use it to do the grunt work for them and just make use of the results. This describes the most common use case for gems.

Second: However, you could also extract the framework of your CLI project layout into a generator gem for others to easily create their own CLI project layouts. This is how Rails came to be.