[swift-evolution] [Review] SE-0101: Rename sizeof and related functions to comply with API Guidelines

[Xiaodi Wu]

On Wed, Jun 29, 2016 at 4:29 PM, David Sweeris via swift-evolution <
swift-evolution at swift.org> wrote:

> (While I was typing this up, I realized that the exact usage you’re
> worried about, “MemoryLayout(Int.self).size” won’t compile, since
> `MemoryLayout` currently doesn’t have instance properties. If you’re
> worried about someone incorrectly typing out
> “MemoryLayout(Int.self).dynamicType.size”, though…)
>
> I made a rather critical typo in my earlier reply. It should’ve been
> “init(_: T.Type)”, instead of “init(_: T.self)”, which is to say this:
> extension MemoryLayout { // assuming `MemoryLayout<T>` is already defined
> as proposed
>     public init(_ : T.Type) {} // makes it so that `MemoryLayout(T.self)`
> still has the correct type for `T`
> }
>
> Here are the results of some quick playgrounding in the WWDC Xcode 8 beta:
> // without `init(_ : T.Type)` defined
> MemoryLayout<Int8>.size                       // 1, correct
> MemoryLayout(Int8.self).dynamicType.size      // 8, almost certainly wrong
> //MemoryLayout(Int8).dynamicType.size           // error
> MemoryLayout(0 as Int8).dynamicType.size      // 1, correct
> MemoryLayout<Int8.Type>.size                  // 8, correct
> MemoryLayout(Int8.Type.self).dynamicType.size // 8, correct, but is oddly
> worded
> //MemoryLayout(Int8.Type).dynamicType.size      // error
>
> // with `init(_ : T.Type)` defined
> MemoryLayout<Int8>.size                       // 1, correct
> MemoryLayout(Int8.self).dynamicType.size      // 1, almost certainly
> correct
> MemoryLayout(Int8).dynamicType.size           // 1, almost certainly
> correct
> MemoryLayout(0 as Int8).dynamicType.size      // 1, correct
> MemoryLayout<Int8.Type>.size                  // 8, correct
> MemoryLayout(Int8.Type.self).dynamicType.size // 8, correct, but is oddly
> worded
> MemoryLayout(Int8.Type).dynamicType.size      // 8, correct
>
> The only value that changes (aside from the errors) is the one “typo” that
> you were worried about.
>
> Do this change your mind?
>

These examples make no sense to me. Why are we asking for the size of the
dynamicType of MemoryLayout?


>
>
>
> On Jun 29, 2016, at 12:34 PM, Dave Abrahams <dabrahams at apple.com> wrote:
>
>
>
> on Wed Jun 29 2016, David Sweeris <davesweeris-AT-mac.com
> <http://davesweeris-at-mac.com>> wrote:
>
> Would adding a "init(_: T.self) {...}" solve that issue?
>
>
> ? I don't see how.
>
>
> Sent from my iPhone
>
> On Jun 29, 2016, at 01:54, Dave Abrahams via swift-evolution <
> swift-evolution at swift.org> wrote:
>
> My worry is that people will write
>
> MemoryLayout(Int.self).size
>
> when they mean
>
> MemoryLayout<Int>.size
>
> (often because for some reason they don't like angle brackets).
>
> I prefer to make the uncommon case much harder to write.
>
>
> --
> Dave
>
>
>
> - Dave Sweeris
>
>
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> swift-evolution at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution
>
>
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