[swift-evolution] [Proposal] Make non-escaping closures the default

John McCall rjmccall at apple.com
Wed Jun 8 12:17:10 CDT 2016

> On Jun 7, 2016, at 7:25 PM, Brent Royal-Gordon via swift-evolution <swift-evolution at swift.org> wrote:
>> @escaping would be part of the parameter type just as @noescape is today. Your foo(closure:) example wouldn't compile with my proposal, the same as today if you marked the parameter with @noescape. Non-escaping function parameters are only allowed to be called. They can't be assigned to variables.
> Okay, that does correct that issue. Although it raises a separate issue: a bare closure type now means something different in a parameter list than anywhere else.

@escaping is really a parameter-specific aspect of the outer function type, not an aspect of the parameter's type.  It's just like something like NS_CONSUMED in Objective-C ARC.


> Are generic types which happen to be functions in some particular use automatically @escaping? Are typealiases and associated types automatically @escaping?
> Also, if `@escaping` is a part of the parameter list syntax (like `inout`) instead of the type syntax (like `@autoclosure`), would it make sense to drop its `@` sign to make them more syntactically similar?
> -- 
> Brent Royal-Gordon
> Architechies
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