[swift-users] Lazy expression is ambiguous?

Quinn "The Eskimo!" eskimo1 at apple.com
Mon Sep 12 02:02:41 CDT 2016

On 12 Sep 2016, at 06:40, Jacob Bandes-Storch via swift-users <swift-users at swift.org> wrote:

> I'd recommend filing a bug at bugs.swift.org.


Also, you can work around this by adding a type.

  lazy var myQ: DispatchQueue = DispatchQueue(label: "Op", attributes: .concurrent)

Also, with regards this specific example, be aware that lazy properties aren’t guaranteed to be initialised only once.  To quote “The Swift Programming Language”:

    If a property marked with the `lazy` modified is accessed by multiple 
    threads simultaneously and the property has not yet been initialized, 
    there is no guarantee that the property will be initialized only once.

I’m struggling to think of a case where that limitation is acceptable in the context of a dispatch queue (-:

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Quinn "The Eskimo!"                    <http://www.apple.com/developer/>
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

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