Advice to make getfield(::NamedTuple, ::Symbol) typestable

[Henrique_Becker]

@ianfiske

Thank you all for the advice! I have a solution that generates the Val -based getfield functions automatically for all of the symbols I need using some metaprogramming.

uhmm, I believe this is not really necessary, you can just take the Val(symbol_value) as f(::Val{symbol_value}) where {symbol_value} = ... and use symbol_value normally inside the function. No eval is needed.

@ianfiske

I also needed to add a stored property in my structs so that they are parameterized by the Val{id} of their id field.

I also believe you do not need this. You can just:

struct MyStruct{MySymbol}
    x :: Int
end

f(my_struct :: MyStruct{my_symbol}) where {my_symbol} = ...

This is, you can add a type parameter to a struct without having a field of that type, and the function will specialize on the MyStruct with the specific type parameter, and the type parameter may be a Symbol directly (it does not need to be wrapped in Val), Ints are also an exception to the rule and can be used directly (this is how Array{Float64, 2} works, the 2 is an Int value being used as type parameter).

@ianfiske

The only problem is that now I’m suffering from some world-age problems due to the @eval 'd new getfield-like methods. I have a hack currently that works for testing (manually re-evaluating calling functions) within vscode after the @eval 'd functions have been created.

I really feel like you are over-complicating here.