As I understand it, we are supposed to use withUnsafe{Mutable/Buffer}Pointer or
withExtendedLifetime to guarantee that objects we take pointers of will exist
and won’t be optimised out by the compiler.
However, this leads to a problem when trying to initialise something which
expects a UTF8 string using only the standard library (not Foundation’s
equivalent cStringUsingEncoding):
> extension DispatchIO {
>
> convenience init(type: DispatchIO.StreamType, path: String, oflag:
> Int32, mode: mode_t, queue: DispatchQueue, cleanupHandler: (error: Int32) ->
> Void) {
>
> let utf8Path = path.nulTerminatedUTF8
> utf8Path.withUnsafeBufferPointer {
> self.init(type: type, path:
> UnsafePointer($0.baseAddress!), oflag: oflag, mode: mode, queue: queue,
> cleanupHandler: cleanupHandler)
> }
> }
> }
ERROR: Initializer delegation ('self.init') cannot be nested in another
expression
I don’t really understand why that isn’t allowed for a non-capturing closure,
but if we accept that, how do I actually use those pointer/extended lifetime
functions to initialise things?
Thanks
Karl
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