[rust-dev] proposal for auto-unboxing and impls

Niko Matsakis niko at alum.mit.edu
Thu Apr 19 06:56:35 PDT 2012


On 4/19/12 6:32 AM, Marijn Haverbeke wrote:
> How about intermediate half-unboxed types? (If there's an impl for @X,
> can you directly call its methods on @@X?)

No.  Under this proposal, you would have to do (*x).foo() in that case.  
I was trying to avoid looping through types, unboxing a step at a time 
and scanning for impls.  That seemed to me to be very close to selecting 
the most specific type, something we have hitherto avoided.  But I guess 
the loop doesn't have to stop.  You could scan all the way through and 
at the end there should still be only one match.  I'm not sure which I 
prefer.  I guess I'd basically be happy either way.



Niko


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