On Tuesday, 20 February 2018 at 16:12:17 UTC, Adam D. Ruppe wrote:
On Monday, 19 February 2018 at 08:28:22 UTC, aliak wrote:
T is the wrapped type. So if T has a member (in the example
it's the built in field "max") then forward that.
Oh, I see what you mean.
So the problem is that built in types don't have "members" per
se, they have "magic". The built in properties don't count to
`hasMember`. You could probably do `if(__traits(compiles,
mixin("a." ~ member))` though.
I assume this should work because rules for alias this (as I
understand) are to basically try if there's a member name that
resolves the call, else forward to alias this.
yeah, just built in properties/members don't pass the same
existence checks so that's confusing your template constraint.
I believe the same happens if it's not a built in property. You
can replace B!int with B!S and have S contains a function "f"
(for instance), then whether or the not constraint on opDispatch
is:
__traits(compiles, mixin("t." ~ name))
or
hasMember(T, name)
You still get:
b.p.writeln; // Error: no property 'p' for type 'B!(S)'
