[swift-evolution] Pitch: Improved Swift pointers

Andrew Trick atrick at apple.com
Wed Jul 19 11:01:42 CDT 2017


> On Jul 18, 2017, at 9:42 PM, Taylor Swift <kelvin13ma at gmail.com> wrote:
> 
> How do we feel about changing the label to `repeated:`, even in cases where `count:` is 1?
> 
> This would mean that calls would read like this: `ptr.initialize(repeated: value)`

Right. Given the default `count` of 1, it’s probably best to stick with `to: value`.
-Andy
> 
> A grep through the stdlib shows that this is by far the most common use case:
> 
> swift-source/swift$ grep initialize\(to: . -r
> ./stdlib/private/SwiftPrivatePthreadExtras/SwiftPrivatePthreadExtras.swift:    result.initialize(to: block(arg))
> ./stdlib/private/StdlibUnittest/OpaqueIdentityFunctions.swift:  ptr.initialize(to: x)
> ./stdlib/private/SwiftReflectionTest/SwiftReflectionTest.swift:  anyPointer.initialize(to: any)
> ./stdlib/private/SwiftReflectionTest/SwiftReflectionTest.swift:  fn.initialize(to: ThickFunction0(function: function))
> ./stdlib/private/SwiftReflectionTest/SwiftReflectionTest.swift:  fn.initialize(to: ThickFunction1(function: function))
> ./stdlib/private/SwiftReflectionTest/SwiftReflectionTest.swift:  fn.initialize(to: ThickFunction2(function: function))
> ./stdlib/private/SwiftReflectionTest/SwiftReflectionTest.swift:  fn.initialize(to: ThickFunction3(function: function))
> ./stdlib/private/SwiftPrivate/ShardedAtomicCounter.swift:      (shards + i).initialize(to: 0)
> ./stdlib/public/SDK/Foundation/NSError.swift:    out.initialize(to: bridged)
> ./stdlib/public/core/UnsafeRawPointer.swift.gyb:    //   (self.assumingMemoryBound(to: T.self) + i).initialize(to: source[i])
> ./stdlib/public/core/UnsafeRawPointer.swift.gyb:      //   .initialize(to: (source + i).move())
> ./stdlib/public/core/UnsafeRawPointer.swift.gyb:      //   (--dst).initialize(to: (--src).move())
> ./stdlib/public/core/Arrays.swift.gyb:      p.initialize(to: repeatedValue)
> ./stdlib/public/core/Arrays.swift.gyb:    (_buffer.firstElementAddress + oldCount).initialize(to: newElement)
> ./stdlib/public/core/Arrays.swift.gyb:        p.initialize(to: x)
> ./stdlib/public/core/Arrays.swift.gyb:      p.initialize(to: newValues[q])
> ./stdlib/public/core/Arrays.swift.gyb:        (base + newCount).initialize(to: next)
> ./stdlib/public/core/AnyHashable.swift:    result.initialize(to: value)
> ./stdlib/public/core/AnyHashable.swift:        result.initialize(to: value)
> ./stdlib/public/core/AnyHashable.swift:  target.initialize(to: AnyHashable(value))
> ./stdlib/public/core/ArrayCast.swift:  target.initialize(to: _arrayForceCast(source.pointee))
> ./stdlib/public/core/ArrayCast.swift:    target.initialize(to: result)
> ./stdlib/public/core/ContiguousArrayBuffer.swift:      (resultPtr + i).initialize(to: _bridgeAnythingToObjectiveC(p[i]))
> ./stdlib/public/core/ContiguousArrayBuffer.swift:    p.initialize(to: source[i])
> ./stdlib/public/core/ContiguousArrayBuffer.swift:    p.initialize(to: element)
> ./stdlib/public/core/ArrayBuffer.swift:      result.initialize(to: result.pointee)
> ./stdlib/public/core/HashedCollections.swift.gyb:  target.initialize(to: _setDownCast(source.pointee))
> ./stdlib/public/core/HashedCollections.swift.gyb:    target.initialize(to: result)
> ./stdlib/public/core/HashedCollections.swift.gyb:  target.initialize(to: _dictionaryDownCast(source.pointee))
> ./stdlib/public/core/HashedCollections.swift.gyb:    target.initialize(to: result)
> ./stdlib/public/core/HashedCollections.swift.gyb:    (keys + i).initialize(to: k)
> ./stdlib/public/core/HashedCollections.swift.gyb:    (keys + toEntryAt).initialize(to: (from.keys + at).move())
> ./stdlib/public/core/HashedCollections.swift.gyb:    (keys + i).initialize(to: k)
> ./stdlib/public/core/HashedCollections.swift.gyb:    (values + i).initialize(to: v)
> ./stdlib/public/core/HashedCollections.swift.gyb:    (keys + toEntryAt).initialize(to: (from.keys + at).move())
> ./stdlib/public/core/HashedCollections.swift.gyb:    (values + toEntryAt).initialize(to: (from.values + at).move())
> ./stdlib/public/core/ReflectionLegacy.swift:  out.initialize(to: String(reflecting: x))
> 
> ./stdlib/public/core/ManagedBuffer.swift:    p.headerAddress.initialize(to: initHeaderVal)
> ./stdlib/public/core/ManagedBuffer.swift:      $0.initialize(to: 
> ./stdlib/public/core/ArrayBufferProtocol.swift:        (elements + j).initialize(to: newValues[i])
> ./stdlib/public/core/Sequence.swift:        ptr.initialize(to: x)
> ./stdlib/public/core/HeapBuffer.swift:      $0.initialize(to: Header(initializer))
> ./stdlib/public/core/UnsafeBitMap.swift:    values.initialize(to: 0, count: numberOfWords)
> ./stdlib/public/core/String.swift:    resultStorage.initialize(to: 
> ./test/api-digester/stdlib-stable.json:          "printedName": "initialize(to:count:)",
> ./test/Generics/slice_test.swift:        (newbase + i).initialize(to: (base+i).move())
> ./test/Generics/slice_test.swift:    (base+length).initialize(to: elem)
> ./test/Parse/pointer_conversion.swift.gyb:  p.initialize(to: t)
> 
> ./test/stdlib/Reflection.swift:sanePointerString.initialize(to: "Hello panda")
> 
> ./test/stdlib/Builtins.swift:  (buf + 0).initialize(to: value)
> ./test/stdlib/Builtins.swift:  (buf + 1).initialize(to: value)
> ./test/stdlib/Renames.swift:  x.initialize(e) // expected-error {{'initialize' has been renamed to 'initialize(to:)'}} {{5-15=initialize}} {{16-16=to: }} {{none}}
> ./test/stdlib/Renames.swift:  x.initialize(with: e) // expected-error {{'initialize(with:count:)' has been renamed to 'initialize(to:count:)'}} {{5-15=initialize}} {{16-20=to}} {{none}}
> ./test/stdlib/Renames.swift:  ptr1.initialize(with: e, count: 1) // expected-error {{'initialize(with:count:)' has been renamed to 'initialize(to:count:)'}} {{8-18=initialize}} {{19-23=to}} {{none}}
> ./test/Sanitizers/asan.swift:a.initialize(to: 5)
> ./validation-test/stdlib/UnsafeBufferPointer.swift.gyb:  allocated.initialize(to: 1.0, count: count)
> ./validation-test/stdlib/UnsafeBufferPointer.swift.gyb:  allocated.initialize(to: 1.0, count: count)
> ./validation-test/stdlib/StringSlicesConcurrentAppend.swift:  barrierVar!.initialize(to: _stdlib_pthread_barrier_t())
> ./validation-test/stdlib/Prototypes/PersistentVector.swift.gyb:    (_keyVector(layout: layout) + keyCount).initialize(to: key)
> ./validation-test/stdlib/Prototypes/PersistentVector.swift.gyb:    (_valueVector(layout: layout) + keyCount).initialize(to: value)
> ./validation-test/stdlib/Prototypes/PersistentVector.swift.gyb:    (_valueArray + i).initialize(to: value)
> ./validation-test/stdlib/Prototypes/PersistentVector.swift.gyb:    keyArray.initialize(to: key0)
> ./validation-test/stdlib/Prototypes/PersistentVector.swift.gyb:    (keyArray + 1).initialize(to: key1)
> ./validation-test/stdlib/Prototypes/PersistentVector.swift.gyb:    valueArray.initialize(to: value0)
> ./validation-test/stdlib/Prototypes/PersistentVector.swift.gyb:    (valueArray + 1).initialize(to: value1)
> ./validation-test/stdlib/Prototypes/PersistentVector.swift.gyb:    (_keyArray + i).initialize(to: key)
> ./validation-test/stdlib/Prototypes/PersistentVector.swift.gyb:    (_valueArray(layout: layout) + i).initialize(to: value)
> ./validation-test/stdlib/Prototypes/PersistentVector.swift.gyb:    (keyArray + layout.keyCount - 1).initialize(to: appendKey)
> ./validation-test/stdlib/Prototypes/PersistentVector.swift.gyb:    (valueArray + layout.keyCount - 1).initialize(to: appendValue)
> ./validation-test/compiler_crashers_2_fixed/0004-rdar20564605.swift:      p.initialize(to: element)
> ./validation-test/compiler_crashers_2_fixed/0003-rdar20564378.swift:      p.initialize(to: element)
> ./validation-test/compiler_crashers_2_fixed/0006-rdar20588474.swift:      p.initialize(to: element)
> ./validation-test/compiler_crashers_2_fixed/0010-rdar20638881.swift:      p.initialize(to: element)
> 
> 
> On Tue, Jul 18, 2017 at 4:33 PM, Andrew Trick <atrick at apple.com <mailto:atrick at apple.com>> wrote:
> 
>> On Jul 18, 2017, at 11:36 AM, Taylor Swift <kelvin13ma at gmail.com <mailto:kelvin13ma at gmail.com>> wrote:
>> 
>> > fix the ordering of the arguments in initializeMemory<Element>(as:at:count:to:)
>> 
>> I think this ordering was an attempt to avoid confusion with binding
>> memory where `to` refers to a type. However, it should be consistent
>> with `UnsafePointer.initialize`, so we need to pick one of those to
>> change.
>> 
>> This would be a non-issue had we just been consistent with the rest of the stdlib and named this argument `repeating:` instead of `to:`. But `ptr.initialize(repeating: 255, count: 100)` doesn’t read quite as naturally in English as `ptr.initialize(to: 255, count: 100)` which is why I left this idea out of the proposal. Now that you mention the problem with `initializeMemory<Element>(as:at:count:to:)`, it might be a good idea to add this rename back into it.
> 
> I think `repeating` is much more clear.
> 
> -Andy
> 

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