> On Nov 1, 2016, at 11:55 AM, Manfred Schubert via swift-users > <swift-users@swift.org> wrote: > > The "UnsafeRawPointer Migration" guide talks about "binding memory to a type“ > as if that was a well known term. I have never heard of it yet though, and > googling it returns no relevant results. I do not understand what binding > memory is supposed to do. > > The migration guide says "Binding uninitialized memory to a type prepares the > memory to store values of that type“, but clearly raw memory does not need to > be prepared (and cannot be) to hold any arbitrary type and value. > > So what is this for, what does it actually do, and to whom is it done (the > raw pointer, or the typed pointer which is returned, or the raw memory)? > > > Manfred
Hi Manfred, At the top of the migration guide is a link to the memory model explanation: https://github.com/apple/swift-evolution/blob/master/proposals/0107-unsaferawpointer.md#memory-model-explanation "A memory location's bound type is an abstract, dynamic property of the memory used to formalize type safety.” I’m not sure I like the “prepares the memory” language myself. Binding memory communicates to the compiler that the memory locations are safe for typed access. Nothing happens at runtime--until someone writes a type safety sanitizer. It affects the abstract state of the memory location, independent of the pointer variable used to access that memory. Binding memory returns a typed pointer for convenience and clarity, but there’s nothing special about that particular pointer value. Initialized memory is always bound to some type. A rawpointer can be used to access that memory without knowing its bound type. -Andy _______________________________________________ swift-users mailing list swift-users@swift.org https://lists.swift.org/mailman/listinfo/swift-users
