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? 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 > >
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