We all love Ruby, of course. One reason for that is the “Principle of Least Surprise”. But there are still many ways in which Ruby can surprise us! Some are good, but some… not so much.

This talk is about Ruby’s lurking “gotchas”, so that you can avoid being “gotten”. They range from basic differences from most other languages (or common sense, or common claims about Ruby), to ones that often catch even expert Rubyists. You will come away with an awareness of specific things to watch out for, and a "Spidey-Sense" of some general kinds of things also likely to be dangerous.

This has been done before at some Washington DC area Meetups, but long ago (over a decade), and not yet at conferences.

You can see the old slides at https://bit.ly/RubyGotchas -- but my slide style has changed a lot, and I intend to reformat it into the illustrated story of a new Rubyist encountering many of these gotchas (there won't be time for all of them, and many have been fixed) one by one.

At the start I breeze through some rank beginner things (like how single quoted strings don’t allow interpolation), but then progress on through intermediate gotchas (like using an object for a hash's default, making all missing references go to that same object) and then to much more advanced things in the end (like comparing procs and lambdas and what happens when you confuse one for the other).

There will certainly be code, but I don't intend to do any *live* coding.

When I did it I only had a couple years of Ruby under my belt, but several longtime Rubyists told me there were things in it that they didn't know about!