The easy but you have to know it...

Yeah, this is the one that is probably make me look like a complete newbie. I've been developing apps in Ruby mostly on Ubuntu but lately I've turned back to Windows and found out that on this platform not everything is taken for granted like it was on Ubuntu. So for that reason I'm making this note so that I don't forget.

If you're installing Ruby gems on Windows and they require compilation of some native extensions (like the JSON thing or Thin) then you need a C compiler to do that. In fact you can do that in multiple ways but there's one easy one that'll take the pain out of your neck in seconds.

What you do is you download the DevKit package, un-7zip it (it's actually a self-extracting archive so that's easy), cd to the directory where you unzipped it and execute the following 3 commands:

ruby dk.rb init
ruby dk.rb review (and make sure your Ruby installation is at correct place)
ruby dk.rb install

With that in place test it by issuing for example:

gem install json

and you should see the following

Fetching: json-1.5.1.gem (100%)
Temporarily enhancing PATH to include DevKit...
Building native extensions.  This could take a while...
Successfully installed json-1.5.1
1 gem installed

Have fun!