> On Oct 9, 2016, at 3:43 PM, Charles Srstka via swift-evolution
> <firstname.lastname@example.org> wrote:
> Let extensions introduce stored properties, but only in the same module as
> the type’s definition. Then, the compiler can just take any extensions into
> consideration when it’s determining the size of the type, just as if the
> properties had been declared in the type. Declaring stored properties on an
> extension outside of the type’s module results in a compiler error, exactly
> as today. This would, without any performance drawbacks, solve one of the big
> problems that people are hoping to solve via stored properties in
> extensions—the ability to organize members by protocol conformance.
Yes please! A big strong +1 to this from me. I can think of several specific
chunks of problem code that this would clean up immensely.
Contra Karl in another message, it’s _in-module_ stored property extensions
that I want most frequently. By far.
It seems to me that Charles’s idea could be introduced as its own proposal. If
out-of-module stored property extensions do eventually become feasible, then
Charles’s proposal is a good stepping stone. If they never do, then his
proposal has done no harm.
I realize this probably falls into the post-ABI stability bucket, but I’d love
to help write/support the proposal when its time comes.
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