UndefVarError from closure inside @batch

[svretina]

I am trying to use the @batch as an alternative to the Base.Threads.@threads but inside my loops I need to define some closures which produced an UndefVarError. A MWE is the following

function func()
    @batch for i in 1:5
        f(x)=x
    end
end
func()

will produce:

ERROR: UndefVarError: `x` not defined
Stacktrace:
 [1] macro expansion
   @ ~/.julia/packages/Polyester/HaBfT/src/closure.jl:387 [inlined]
 [2] func()
   @ Main ./REPL[90]:2
 [3] top-level scope
   @ REPL[91]:1
 [4] top-level scope
   @ ~/.julia/juliaup/julia-1.10.0+0.x64.linux.gnu/share/julia/stdlib/v1.10/REPL/src/REPL.jl:1428

Is there a workaround or its a case that I cannot use @batch?

[chriselrod]

You could define a callable struct instead.

julia> struct Mul{T}
           x::T
       end

julia> (x::Mul)(y) = x.x * y

julia> using Polyester

julia> function func!(y,x)
           @batch for i = eachindex(y,x)
               y[i] = Mul(i)(x[i])
           end
       end
func! (generic function with 1 method)

julia> x = rand(1000); y = similar(x);

julia> func!(y, x)

julia> y == x .* eachindex(y,x)
true

[svretina]

thanks for your reply! That solves my issue, thank you.

although it worked and I got 0 allocations with @batch, for my case
the performace was worse than @threads but this should be due to my
definitions of the function-like objects etc.