[Pitch #3] Property wrappers (formerly known as Property Delegates)

Evolution Pitches
105

This new pitch is the best by far. I really like it.

Some minor things I see (but can make peace with):

  • Shouldn't @Swift.Lazy be Swift.@Lazy?

  • public(wrapper) is ambigious for nested wrappers.
    public fileprivate(@A) public(@B) var x is not.

  • I (still) would prefer an postfix operator $ on wrappers to access the underlying storage:

    @Lazy var foo: Int = 42
foo$.reset(42)

    That way, the wrapper's storage appears more like a property of the wrapped value. Within a property wrapper, self$ could refer to the “enclosing self”.

  • Thinking about the future:

    @propertyWrapper struct Bla<Value where Value : Hashable>
{…}

    limits the wrapper to hashable variables?

    Once "enclosing self" is there, will

    @propertyWrapper struct Bla : Broadcaster {…}

    require enclosing self to conform to Broadcaster?

    Shouldn't that be:

    @propertyWrapper<Value where Value:Hashable> : Broadcaster
struct Bla { … }