Hi, > On 20 Jul 2017, at 5:41 pm, Taylor Swift <kelvin1...@gmail.com> wrote: > > Does addressof count as legally observing it? > > var buffers:(GL.UInt, GL.UInt) = (0, 0) > glGenBuffers(n: 2, buffers: &buffers.0) > > Also, I assume Swift performs a swizzle if the tuple is defined in a separate > module from where the pointer to it is constructed?
yes, that's legal assuming the called function doesn't store the pointer and read/write it later. > > On Thu, Jul 20, 2017 at 4:59 AM, Johannes Weiß <johanneswe...@apple.com> > wrote: > When you can (legally) observe it, tuples in Swift have guaranteed standard > C-style layout. > > John McCall confirms this here: > https://lists.swift.org/pipermail/swift-dev/Week-of-Mon-20170424/004481.html > > > On 20 Jul 2017, at 4:33 am, Taylor Swift via swift-users > > <swift-users@swift.org> wrote: > > > > Many APIs like OpenGL take arrays where the atomic unit is multiple > > elements long. For example, a buffer of coordinates laid out like > > > > :[Float] = [ x1, y1, z1, x2, y2, z2, ... , xn, yn, zn ] > > > > I want to be able to define in Swift (i.e., without creating and importing > > a Objective C module) a struct that preserves the layout, so that I can do > > withMemoryRebound(to:capacity:_) or something similar and treat the buffer > > as > > > > struct Point > > { > > let x:Float, > > y:Float, > > z:Float > > } > > > > :[Point] = [ point1, point2, ... , pointn ] > > > > The memory layout of the struct isn’t guaranteed, but will the layout be > > guaranteed to be in declaration order if I use a tuple inside the struct > > instead? > > > > struct Point > > { > > let _point:(x:Float, y:Float, z:Float) > > > > var x:Float > > { > > return self._point.x > > } > > > > var y:Float > > { > > return self._point.y > > } > > > > var z:Float > > { > > return self._point.z > > } > > } > > > > This is an ugly workaround, but I can’t really think of any alternatives > > that don’t involve “import something from Objective C”. I am aware that the > > implementation of structs currently lays them out in declaration order, but > > I’m looking for something that’s actually defined in the language. > > > > > > _______________________________________________ > > swift-users mailing list > > swift-users@swift.org > > https://lists.swift.org/mailman/listinfo/swift-users > > _______________________________________________ swift-users mailing list swift-users@swift.org https://lists.swift.org/mailman/listinfo/swift-users
