OffsetArrays, inbounds, and confusion

Internals & Design
,
31

Not too tough:

julia> function f!(A)
           for (count, idx) in enumerate(eachindex(A))
               A[idx] = count*2
           end
       end
f! (generic function with 1 method)

julia> f!(A); @allocated f!(A)
0

Or this works as a slightly less-quick sanity check, too:

julia> using BenchmarkTools

julia> function g!(A)
           i = 0
           for idx in eachindex(A)
               i += 1
               A[idx] = i*2
           end
       end

julia> @btime f!($A)
  11.029 ns (0 allocations: 0 bytes)

julia> @btime g!($A)
  13.349 ns (0 allocations: 0 bytes)

Amusingly, that difference does seem real — your “comfortable” construction is actually slower :stuck_out_tongue:

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