[Pitch #5] SE-0293: Extend property wrappers to function and closure parameters

[hborla (Holly Borla)]

@Philippe_Hausler

I could see it to be quite useful to have the application of the property wrapper to be enforced to the consumer of foo in this case and that would allow for some nifty advances of the syntax for wrappers.

This was also suggested in the previous review. I don't think there's anything in the current proposal preventing this in the future:

SE-0293 (second review): Extend Property Wrappers to Function and Closure Parameters

I think what you're suggesting is allowing property wrapper attributes only in parameter type positions to force the argument function to have the same wrapper attribute on that parameter, and to allow inference of the wrapper attribute on closure parameters. I still think a syntactic indication that you have a property wrapper is valuable, but I also don't think there's anything in this proposal preventing such a feature from being proposed in the future. FWIW, there are a few more downsides t…

I also think it's out of scope for this proposal:

SE-0293 (second review): Extend Property Wrappers to Function and Closure Parameters

I maintain that expanding property wrapper attributes to types, even if only in the parameter position, is out of scope for this proposal. What you're proposing is a bit of sugar on top of this proposal that comes with a lot of implementation complexity and downsides that haven't been fully considered yet. It also doesn't change anything about the base model of property wrappers on parameter declarations, so nothing is preventing someone from proposing this in the future. The APIs you mention a…