Allocation-free type hiding?

General Usage Performance
,
12

Thanks @pdeffebach . However this kind of strategy is analogous to the _test barrier, which doesn’t solve my problem.

The following is promising, though:

julia> import FunctionWrappers

julia> import FunctionWrappers: FunctionWrapper

julia> struct S
           f::FunctionWrapper{Bool,Tuple{Float64}}
       end

julia> test(s::S, r::Float64) = s.f(r)
test (generic function with 1 method)

julia> x = S(FunctionWrapper{Bool,Tuple{Float64}}(r -> r < 0.5));

julia> function run(s::S)
           z = 0
           for _ in 1:1e5
               r = rand()
               z += test(s, r)
           end
           return z
       end
run (generic function with 1 method)

julia> using BenchmarkTools; @btime run($x)
  601.449 μs (0 allocations: 0 bytes)

Maybe the trick is to wrap everything inside a test::FunctionWrapper…