[swift-evolution] Pitch: Improved Swift pointers

Taylor Swift kelvin13ma at gmail.com
Tue Jul 18 23:42:01 CDT 2017


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)`

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> wrote:

>
> On Jul 18, 2017, at 11:36 AM, Taylor Swift <kelvin13ma at gmail.com> wrote:
>
> > fix the ordering of the arguments in initializeMemory<Element>(as:a
>> t: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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