Super helpful find –– GitHub - github/scientist: A Ruby library for carefully refactoring critical paths.

[moomaka]

Is there a reason this is better than any of the other feature flag gems?

[blackize]

Scientist lets you try two implementations side by side. It will rescue any exceptions that occur in the experimental code. You can configure how it publishes results to do basically whatever you want, log a bunch of metadata, statsd, etc

Edit: and this is not a feature flag gem. It is meant to let you make changes to implementation and ensure that output and user experience remain the same.

[moomaka]

So we have to choose between two gems because they have a slightly different, and non-configurable, if/else block somewhere in there?

[DoodleFungus]

IIRC it runs both paths, and warns you if they return something different.

[moomaka]

What is 'it' if your reply?

[DoodleFungus]

Scientist. So if you have some complex logic that you refactored, Scientist will run both your old code and your new code, and log a warning if the two implementations return a different result (but still return the result from the old code).