3 ms·

My 'principle' for DRY is : twice is fine, trice is worth an abstraction (if you think it has a small to moderate chance to happen again). I used to apply it no

• whstl 2y ago
  I really dislike how this principle ends up being used in practice. A good abstraction that makes actual sense is perfectly good even when it's used only once. On the other hand, the idea of deduplicating code by creating an indirection is often not worth it for long-term maintenance, and is precisely the kind of thing that will cause maintenance headaches and anti-patterns. For example: don't mix file system or low-level database access with your business code, just create a proper abstraction. But deduplicating very small fragments of same-abstraction-level can have detrimental effects in the long run.
  • ahoka 2y ago
    I think the main problem with these abstractions that they are merely indirections in most cases, limiting the usefulness to several use cases (sometimes to things that never going to be needed). To quote Dijsktra: "The purpose of abstraction is not to be vague, but to create a new semantic level in which one can be absolutely precise."
  • n0w 2y ago
    I can't remember where I picked it up from, but nowadays I try to be mindful of when things are "accidentally" repeated and when they are "necessarily" repeated. Abstractions that encapsulate the latter tend to be a good idea regardless of how many times you've repeated a piece of code in practice.
    • codeflo 2y ago
      Exactly, but distinguishing the two that requires an excellent understanding of the problem space, and can’t at all be figured out in the solution space (i.e., by only looking at the code). But less experienced people only look at the code. In theory, a thousand repetitions would be fine if each one encodes an independent bit of information in the problem space.
  • loup-vaillant 2y ago
    The overarching criterion really is how it affects locality of behaviour: repeating myself and adding an indirection are both bad, the trick is to pick the one that will affect locality of behaviour the least. https://loup-vaillant.fr/articles/source-of-readability#avoid-repeating-yourself https://loup-vaillant.fr/articles/source-of-readability#avoi...
• ikari_pl 2y ago
  twice is fine... except some senior devs apply it to the entire file (today I found the second entire file/class copied and pasted over to another place... the newer copy is not used either)
• tomohawk 2y ago
  "Better a little copying than a little dependency" - Russ Cox
• syntaxfree 2y ago
  WET, write everything twice
• aitchnyu 2y ago
  Do you use a copy paste detector to find third copy?