RubyMine 2018.1 EAP5 (build 181.3986.23) is now out and awaiting your review. The highlight of this build is the postfix code completion that lets you transform an existing expression without the need to move your caret back in the code to reverse, alter, or supplement the statement.
Expressions could come in handy in many different cases. For example, you can quickly create or redesign Ruby methods or Rails actions:
Find a list of all the postfix templates in the settings (Preferences / Settings | Editor | General | Postfix Completion) to learn and play around with all of them. You can always turn off the ones you don’t need, or even disable the whole thing:
Let us know in the comments if you have specific postfix use cases that are not yet supported. Please also report any issues you face to the related ticket directly.
Your RubyMine team