[swift-evolution] [pitch] Adding in-place removeAll to the std lib

[Ben Cohen]

> On Apr 8, 2017, at 5:41 PM, Brent Royal-Gordon <brent at architechies.com> wrote:
> 
>> On Apr 8, 2017, at 12:44 PM, Xiaodi Wu via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>> 
>> +1. Perfect. Let's not bikeshed this and get it done!
> 
> 
> Sorry, I'm going to have to insist on bikeshedding.
> 
> `equalTo:` is kind of ugly and has no precedent in the standard library. Similar APIs seem to either leave the parameter unlabeled or use `of:` (as in `index(of:)`). I think unlabeled is probably the right answer here.
> 

I think removeAll(of:) works well for the equatable value version.

FWIW of all the ideas from the all thread, containsOnly(_:) for the equatable value version works for me. It has a nice symmetry: contains(3) vs containsOnly(3).

> The main shortcoming I can see is that if you see:
> 
> 	array.removeAll(3)
> 

Personally don’t feel good about an unlabelled version. It doesn’t read right. Remove all three what?

> You might think `3` is either an index or a count. But neither of those actually make sense:
> 
> * It can't be an index because then `All` would have no meaning. There's only ever one thing at a given index. Besides, indices are almost always marked with `at:` or another parameter label.
> * It can't be a count because `All` is already a count. What could "remove all 3" possibly mean if the array doesn't happen to have three elements?
> 
> And this is only a problem if the value happens to be an integer. If it's anything else, the type makes clear that this can't possibly be an index or count; it must be an element.
> 
> (But if you really do think this is insurmountable, `removeAll(of: 3)` *is* impossible to misinterpret and fits in better than `removeAll(equalTo:)`.)
> 
> (P.S. The existing oddness of `removeFirst(_:)` compared to `removeFirst()` and `removeAll()` is why I proposed last year that it be renamed to `removePrefix(_:)`, which matches the count-taking `prefix(_:)` method.)
> 
> -- 
> Brent Royal-Gordon
> Architechies
> 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.swift.org/pipermail/swift-evolution/attachments/20170409/8477f4c4/attachment.html>