I recently came across this problem with the ~/.gemrc file used by the gem command since I needed to store a a private token for accessing a GemFury gem source. I struggled to figure out a way to keep the file in my dotfiles without exposing myself to the possibility that I would publish them. Finally, at the end of my rope I reached out to my colleagues with this problem and within minutes Adam Strickland responded with a great approach that was not-obvious but ends up being a great way to provide configuration outside of the committed ~/.gemrc file. A true hidden gem. –do you see what I did there?

Memoization is the pattern of calculating a value once, and re-using that value each subsequent time it is needed. It’s common to encounter this in Ruby in the form @variable ||= calculation. It’s so common that it is often used even where it’s not expensive or re-used; it’s become a part of idiomatic Ruby. In my last post I made an off-hand reference to solving the problem of using memoization for falsy values, and it seems a topic worth talking about in and of itself.

Instrumentation is the addition of measurement to code - for example timing how long Ruby is spending in a given method. There are many approaches to adding instrumentation to code in Ruby - whether it’s using 3rd party services like New Relic and Datadog, using libraries like Rubyprof, or even plain old logging. Here I propose an unintrusive Ruby 2.0+ technique to add instrumentation to arbitrary methods. If you want to jump straight to the proposed code without the explanation of how or why we got there, here’s your TLDR.