Otaku – Cedric's blog

I was recently having a discussion about refactoring dynamically typed languages and I was struck by the amount of misconceptions that a lot of developers still have on this topic.

I expressed my point in this article from fifteen years ago(!), not much has changed, but the idea that it it impossible to safely and automatically refactor a language that doesn’t have type annotations is still something that is not widely accepted, so I thought I would revisit my point and modernize the code a bit.

In languages that do not have type annotations (e.g. Python, Ruby, Javascript, Smalltalk), it is impossible to perform automatic refactorings that are safe, i.e., that are guaranteed to not break the code. Such refactorings require the supervision of the developer to make sure that the new code still runs.

First of all, I decided to adapt the snippet of code I used in my previous article and write it in Python. Here is a small example I came up with:

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