I'm making a Ruby wrapper for a C Library that doesn't really have a system wide installation(the libxxx.a linkable library is distributed). During development, I was able to just keep this .a file in a local folder and refer to it using the C extension code. However this would be cumbersome for anyone who just wants to type gem install into their terminal. Since there is no system wide installation, I would need to execute an intermediate script that downloads the right distribution and then puts it in a generic folder within the gem directory itself.
To be clear, when someone types gem install, a tarball would get downloaded from an ftp, unpacked into the gem folder, and then gem install would proceed normally. If it helps, the C library in question is CSPICE