I’m having real difficulties grok-ing macro hygiene. I’ve read the manual entry, but didn’t get much wiser, so I’m hoping the solution to my current problem will be another data point I can use to understand (and I need this to work :P).
I have a utility function that builds an expression (which will later be interpolated into the method body of a generated function, but that’s out of scope for my current problem), something like this: julia> using Base.Cartesian julia> foo(N) = :(gradient(A, (@ntuple $N k->xs_k)...)) foo (generic function with 1 method) julia> macroexpand(foo(2)) :(gradient(A,(xs_1,xs_2)...)) Now, as you see, the generated tuple is splatted at run time. I’d like to try to move that splatting to compile time, so that the generated expression is rather :(gradient(A, xs_1, xs_2)). I’ve tried variants on the following, but as you can see I haven’t had any success. I assume that I need to escape N somehow - but how? julia> foo(N) = :(gradient(A, $((@ntuple N k->xs_k)...))) ERROR: MethodError: `_ntuple` has no method matching _ntuple(::Symbol, ::Expr) julia> foo(N) = :(gradient(A, $((@ntuple $N k->xs_k)...))) ERROR: MethodError: `_ntuple` has no method matching _ntuple(::Expr, ::Expr) julia> foo(N) = :(gradient(A, $(esc((@ntuple N k->xs_k)...)))) ERROR: MethodError: `_ntuple` has no method matching _ntuple(::Symbol, ::Expr) julia> foo(N) = :(gradient(A, $(esc((@ntuple :N k->xs_k)...)))) ERROR: MethodError: `_ntuple` has no method matching _ntuple(::Expr, ::Expr) julia> foo(N) = :(gradient(A, $(@ntuple esc(N) k->xs_k)...)) ERROR: MethodError: `_ntuple` has no method matching _ntuple(::Expr, ::Expr) julia> foo(N) = :(gradient(A, $(@ntuple esc(:N) k->xs_k)...)) ERROR: MethodError: `_ntuple` has no method matching _ntuple(::Expr, ::Expr)
