问题
As we all know, the common structure of rubygem assumes presence of lib directory. I noticed, that generally in this directory are two items: gem_name.rb and gem_name/ directory. The gem_name/ directory hold main sources of project. It is heart of application. So, the question is about gem_name.rb file. What does it stand for?
回答1:
The reason it's structured like that is if you had files other than gem_name.rb in the lib/ directory (say another_file_name.rb), you'd be liable to cause problems if there was a gem with the name another_file_name and someone did require another_file_name - it'd load your file, rather than the other gem's file.
If your code is small enough it can all fit into gem_name.rb, then put it there, otherwise put it into gem_name/other_file_name.rb.
回答2:
Typically that just requires everything from the gem_name/ directory that's needed. It's used to keep all the requires in a central location and separate from the actual code
来源：https://stackoverflow.com/questions/5214508/common-structure-of-gem