[Lio]

I don't know the authors reason but I've personally always avoided refinements after first reading about their performance hit for JRuby code[0].

I read somewhere recently that even for MRI ruby you can take a 40% hit when using refinements (but please take that with a big pinch of salt as I can't find the source right now).

0. http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/...

[byroot]

The source is me: https://gist.github.com/casperisfine/1c46f05cccfa945cd156f44...

Note that this overhead apply as soon as a refinement is defined for a method regardless of wether it's ever active.

That 40% figure is for an empty method. So for "big" methods that are infrequently called it's probably fine, but it should really be avoided in hotspots.

[Lio]

Aha! Excellent, thank you.

For me refinements are a bit like meta-programming; I'm glad they exist but I think there's other ways to get the same result which are easier to live with.