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Comment by stephencanon | Hacker News Reader

FWIW, that answer (to the second link, after edit) is really old, and you can do string.firstRange(of: substring) since Swift 5.7.

The top answer to your third question gives a pretty good explanation of why Swift string indices work the way they do (as well as showing nicer ways to spell a lot of the operations on them), which mostly addresses the first and third questions. It really seems that your last link is just asking for the `inout` modifier; I'm not sure why that one is especially confusing.

Obviously, there's always stuff that can be further improved, but none of these are especially onerous (once you get past the "string indices are not just integers" step, at least--for people who really just want to pretend the world uses ASCII or work with UTF8 bytes directly, string.utf8 may be an nicer interface to use).

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The thing is, each string-related answer ended up extending it with some methods that everyone wanted it to have in the first place, and the top-voted comments are like "why do we have to do this." It also shouldn't have required multiple updates to each answer.

The time I was doing a lot of string manipulation in a team Swift project, we had to write our own wrapper that basically stored strings as arrays of printable characters because the native one was too annoying. This also protected us from all the breaking changes Apple made to strings across Swift versions.

The inout one is different. It's confusing that arrays and dicts are structs, which have different rules from regular objects, and the syntax takes some getting used to:

  func addItem(_ localArr: inout [Int]) {
    localArr.append(4)
  }

> It's confusing that arrays and dicts are structs, which have different rules from regular objects

As a long-time assembly and C programmer and now Swift programmer, I would say that structs _are_ regular objects, and things with reference semantics are weird. It all depends on your point of view!

I'm fine with either approach as long as it's consistent. Practical Swift code will have a few "inout"s sprinkled around, wherever someone happened to pass in a struct (like array) instead of an object (like NSArray). And that's without bridging and stuff like UnsafePointer involved.

Edit: Just remembered that arrays still don't act like regular structs either! https://stackoverflow.com/questions/24450284/conflicting-def...

I'm fine with either approach if it's easy to know which one I'm using at a any particular call site. C# started the tradition of moving this information to the type level, far away from the call site. Swift has adopted this terrible idea.

The philosophy of making code look "clean" at the cost of hiding critical information in some far away place is the biggest mistake in programming language design. If code happens to look clean it should be the result of being simple rather than being cleansed for effect.

Other bad ideas in the same vein are computed properties and function builders.

What do you mean by moving information to the type level?

In C and C++ (and many other languages) the distinction between value and reference/pointer is part of the variable declaration. In C# and Swift that information belongs to type definitions (except for inout parameters). Structs are value types and classes are reference types.

Type definitions are usually further away from the call site than variable declarations. Also, in C, accessing a member of a struct through a pointer requires the -> operator providing yet another clue as to whether you're using a pointer or a value.

In my opinion, this distinction is absolutely key. It should always be obvious at the call site. I don't think there is anything that has caused more bugs in my Swift code than getting this wrong.

Change a type from class to struct or vice versa and chances are your code still compiles when it really shouldn't because it's now completely broken.

If there are identity having classes (reference/pointer) that may be mutable, and value types that are always immutable, then I think it can be an “implementation detail”, part of the type, not changing semantics.

If you can’t change a struct’s field, only the whole struct, then I believe it’s fine - and the compiler may decide to copy it or change in-place depending on its available context, is it not the case?

In a language without mutability (or perhaps with something like borrow checking?), it would not be a problem. But in Swift, the option of introducing mutability always exists.

It's not impossible to impose some sort of discipline to mitigate these issues, but why is it a good idea to make values and references indistinguishable at the call site? I don't get it.

But it's not surprising. I don't get a lot of decisions that language designers have been making. The entire drive towards more and more syntactical abstraction in order to make everything look like a DSL is a mistake in my opinion.

Refs in C++ go against this, right? At the call site, it's not clear that you're passing in a ref instead of a value. I don't mind it too much cause at least the rules are the same for everything, not different for structs vs classes.

Yes. At least references are still part of the variable type and therefore likely to be closer to the call site.

Computed properties are annoying too. More importantly, they're one more inconsequential thing for SWEs to argue over in code review.

The answer you link to there is from the Swift 1 days in 2014. It was absolutely true then, but array has had true value semantics since shortly after that answer was written.

Ah, it's coming back to me now. I remember when they fixed that and I was relieved.

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