Int.init(ObjectIdentifier) and UInt.init(ObjectIdentifier) should have a
'bitPattern:’ label to make it clear at the use site that we interpret the
value as a bit pattern.
In Swift we have ObjectIdentifier values which uniquely identify a class
instance or metatype. They are implemented as a struct which holds the value of
the reference to the instance or metatype as a raw pointer.
/// A unique identifier for a class instance or metatype.
public struct ObjectIdentifier : Hashable, Comparable {
internal let _value: Builtin.RawPointer
...
}
We have constructors for Int and Uint that capture this value. These
constructors don’t have an argument label.
extension UInt {
/// Create a `UInt` that captures the full value of `objectID`.
public init(_ objectID: ObjectIdentifier) {
self.init(Builtin.ptrtoint_Word(objectID._value))
}
}
extension Int {
/// Create an `Int` that captures the full value of `objectID`.
public init(_ objectID: ObjectIdentifier) {
self.init(bitPattern: UInt(objectID))
}
}
This proposals suggest adding a label ‘bitPattern’ to the constructor:
Int.init(bitPattern: ObjectIdentifier).
extension UInt {
/// Create a `UInt` that captures the full value of `objectID`.
public init(bitPattern objectID: ObjectIdentifier) {
self.init(Builtin.ptrtoint_Word(objectID._value))
}
}
extension Int {
/// Create an `Int` that captures the full value of `objectID`.
public init(bitPattern objectID: ObjectIdentifier) {
self.init(bitPattern: UInt(objectID))
}
}
Motivation
==========
Adding a label ‘bitPattern’ to the constructors makes it clear that we
interpret the pointer value as a bit pattern at the use site. It is similar to
what we do in other APIs, for example in "UInt(bitPattern:
UnsafePointer<Void>(value)))"
Impact on existing code
=======================
Existing code will have to add the bitPattern label.
Alternatives
============
Leave as is.
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