Hello swift-evolution,
I've been thinking about a standard library 'Data' type for a while, analogous
to NSData in the same way Swift's Arrays and Dictionaries are analogous to
NSArrays and NSDictionaries. A first-class container for binary data that is
available to every Swift user, conforms to Swift semantics, and is safer and
easier to work with than UnsafeBufferPointer seems like a natural fit for the
standard library.
As such, I've put together a very preliminary proposal, which can be found
here:
https://github.com/austinzheng/swift-evolution/blob/d2/proposals/XXXX-stdlib-data.md
<https://github.com/austinzheng/swift-evolution/blob/d2/proposals/XXXX-stdlib-data.md>.
I present it not as a way to impose a vision of what such a Data type should
look like, but rather as a way to catalyze discussion (including discussion as
to whether or not a Data type is even a good idea in the first place).
Some thoughts:
- It's not clear if the methods to convert to and from base-64 encoded data are
necessary. The state flag that tries to mark whether or not a Data represents
base-64-encoded string stored as a data may be unnecessary as well.
- I didn't really go into how NSData should be bridged. Special consideration
needs to be given to how any native Data type would interact with the overlays
described in
https://github.com/apple/swift-evolution/blob/master/proposals/0069-swift-mutability-for-foundation.md
<https://github.com/apple/swift-evolution/blob/master/proposals/0069-swift-mutability-for-foundation.md>.
It's possible (and only if a compelling technical reason exists) that the
Foundation implementation of NSData can in the future be moved into
Swift/supplanted by such a native data type, with API extensions to provide
conformance to the Objective-C Foundation API. This proposal should not be seen
as an attempt to usurp Foundation's job, though - there are plenty of
to-be-value types in Foundation whose inclusion directly in the standard
library makes little sense.
- Perhaps Data should be generic over various types of fixed-width integers
(signed and unsigned, 8, 16, 32, 64, machine-width, etc). In that case it might
also provide generic views (for example, to allow iteration over a Data<UInt64>
as if it were a collection of UInt8 bytes). I'm not yet sure if this is
feasible or desirable.
Finally, it's possible that this is strictly Swift 4 territory, in which case
I'm happy to withdraw from discussion until the time is right later this year.
Best regards,
Austin
_______________________________________________
swift-evolution mailing list
swift-evolution@swift.org
https://lists.swift.org/mailman/listinfo/swift-evolution
