How would you feel about: struct UnsafeMutableRawBufferPointer {
--- static func allocate(count:Int) -> UnsafeMutableRawBufferPointer +++ static func allocate(bytes:Int, alignedTo:Int) -> UnsafeMutableRawBufferPointer func deallocate() +++ func bindMemory<Element>(to:Element.Type, capacity:Int) +++ func copy(from:UnsafeRawBufferPointer, bytes:Int) +++ func initializeMemory<Element>(as:Element.Type, at:Int, count:Int, to:Element) +++ func initializeMemory<Element>(as:Element.Type, from:UnsafeBufferPointer<Element>, count:Int) +++ func moveInitializeMemory<Element>(as:Element.Type, from:UnsafeMutableBufferPointer<Element>, count:Int } “bytes” = 8 bit quantities (don’t @ me we’re assuming 8 bit bytes) “capacity” = strided quantities, not assumed to be initialized “count” = strided quantities, assumed to be initialized It’s also worth nothing that a lot of what the proposal tries to add to UnsafeBufferPointer is already present in UnsafeMutableRawPointer like a sizeless deallocate() and a sizeless copyBytes(from:). Although I’m not sure what’s going on with the latter one <https://developer.apple.com/documentation/swift/unsafemutablerawbufferpointer/2635415-copybytes>…lol swiftdoc On Fri, Jul 14, 2017 at 1:57 AM, Andrew Trick <atr...@apple.com> wrote: > > On Jul 13, 2017, at 10:30 PM, Taylor Swift <kelvin1...@gmail.com> wrote: > > I’m confused I thought we were talking about the naming choices for the > argument labels in those functions. I think defining and abiding by > consistent meanings for `count`, `capacity`, and `bytes` is a good idea, > and it’s part of what this proposal tries to accomplish. Right now half the > time we use `count` to refer to “bytes” and half the time we use it to > refer to “instances”. The same goes for the word “capacity”. This is all > laid out in the document: > > “““ > *Finally, the naming and design of some UnsafeMutableRawPointer members > deserves to be looked at. The usage of capacity, bytes, and count as > argument labels is wildly inconsistent and confusing. > In copyBytes(from:count:), count refers to the number of bytes, while > in initializeMemory<T>(as:at:count:to:) and > initializeMemory<T>(as:from:count:), count refers > to the number of strides. > Meanwhile bindMemory<T>(to:capacity:) uses capacity to refer to this > quantity. The always-problematic deallocate(bytes:alignedTo) method > and allocate(bytes:alignedTo:) type methods use bytes to refer to > byte-quantities. Adding to the > confusion, UnsafeMutableRawBufferPointer offers an allocate(count:) type > method (the same signature method we’re trying to add > to UnsafeMutableBufferPointer), except the count in this method refers to > bytes. This kind of API naming begets stride bugs and makes Swift > needlessly difficult to learn.* > ””” > > The only convenience methods this proposal is trying to add is the > functionality on the buffer pointer types. There seems to be broad support > for adding this functionality as no one has really opposed that part of the > proposal yet. Any other new methods like `UnsafeMutablePointer.assign(to:)` > are there for API consistency. > > This proposal also calls for getting rid of one of those “redundant > initializers” :) > > > Since we’re not bike-shedding the specifics yet, I’ll just give you some > background. > > We would ultimately like APIs that allocate and initialize in one go. It’s > important that the current lower-level (dangerous) APIs make a clear > distinction between initialized and uninitialized memory to avoid confusing > them with future (safer) APIs. `capacity` always refers to memory that may > be uninitialized. I think that’s very clear and helpful. > > In the context of pointers `count` should always be in strides. For raw > pointers, that happens to be the same as as `bytes`. > > I initially proposed copy(bytes:from:), but someone thought that `bytes` > in this particular context did not properly convey the "count of bytes" as > opposed to the source of the bytes. You’re right, that’s inconsistent with > allocate/deallocate(bytes:), because allocateBytes(count:) would be silly. > Just be aware that the inconsistency is a result of over-thinking and > excessive bike shedding to the detriment of something that looks nice and > is easy to remember. > > I should also point out that the inconsistencies in functionality across > pointer types, in terms of collection support and other convenience, is > also known but was deliberately stripped from proposals as “additive”. > > -Andy >
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