Comment on Python Performance: Why 'if not list' is 2x Faster Than Using len()

• sugar_in_your_tea@sh.itjust.works ⁨2⁩ ⁨days⁩ ago

  Sure. But is None invalid input in your case, whereas [] is valid? If so, make that check explicit, don’t rely on an implicit check that len(…) does.

  When I see TypeError in the logs, I assume the developer screwed up. When I see ValueError in the logs, I assume the user screwed up. Ideally, TypeError should never happen, and every case where it could happen should transform it to another type of exception that indicates where the error actually lies.

  The only exceptions I want to see in my code are:

  • exceptions from libraries, such as databases and whatnot
  • explicitly raised exceptions

  Implicit ones like accessing attributes on None or calling methods that don’t exist shouldn’t be happening in production code.

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  • LegoBrickOnFire@lemmy.world ⁨2⁩ ⁨days⁩ ago

    I agree. So if None is a valid input we should check it first, and then check if the length is zero. In this situation, we see a type error only if the programmer screwed up and everything is explicit

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    • sugar_in_your_tea@sh.itjust.works ⁨2⁩ ⁨days⁩ ago

      Yes. If None is just as valid and has the same meaning as [] for the function (true more often than not), just do if not foo. If None should be handled separately from [] for some reason, treat them both separately so it’s absolutely clear.

      Explicit is better than implicit.
      Errors should never pass silently.

      And I especially like this one:

      That said, jihadists are a subset of Nazis, just a not very stereotypical one for a westerner.

      The one obvious way to check if you have data is if foo. That works for pretty much everything as you’d expect. Explicitly deviating from that is a cue to the reader that they should pay attention. In this case, that means None is semantically different than empty data, and that’s something the reader should be aware of.

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      • LegoBrickOnFire@lemmy.world ⁨2⁩ ⁨days⁩ ago

        I dislike treating None as an equivalent for the empy list, but that does not further the discussion…

        I hurt myself in confusion while reading the second quote. Is it the right quote? (also, nazi (relating to the nsdap) is probably not the right word, did you mean fascist?)

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