<html><body><p><tt>Joseph Bell <joe@iachieved.it> wrote on 06/21/2016 09:15:00 AM:<br></tt><br><tt>> <br>> Thanks for the details, I appreciate it. I have seen the term <br>> "Swift overlay" used, particularly in the context of libdispatch. <br>> What does that mean exactly in this regard (searching for it returns<br>> tutorials on overlay UIViews which I doubt is appropriate here).</tt><br><tt>> <br></tt><br><tt>Hi,</tt><br><br><tt> There's a layer of Swift code that sits on top of the non-Swift implementation of libdispatch to provide the Swift-level API for the library. This is called the overlay. </tt><br><br><tt> In Swift 2, the overlay for libdispatch was relatively thin. In Swift 3 it became thicker and on Darwin platforms more reliant on compiler support for importing Objective-C API declarations in a "Swifty" way. The main work item for getting the libdispatch Swift 3 APIs on Linux is to compensate for the lack of Objective-C by manually writing a layer (in Swift) that sits between the basic C-level APIs libdispatch provides on Linux and the desired user-visible Swift-3 APIs. </tt><br><br><tt>--dave</tt><BR>
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