Re: Extract a list of keys from table

[Shmuel Zeigerman <shmuz@...>]

Alexander Gladysh wrote:
> print(
>     extract_keys(
>         { a = 1, b = 2, c = 3 },
>         "a", "b", "xxx", "c", "yyy"
>       )
>   )
>  --> 1        2        nil         3        nil

An option is using recursive functions:

-- "mapper" is a table:
function map(tab, ...)
  if select("#", ...) > 0 then
    return tab[...], map(tab, select(2,...))
  end
end

-- "mapper" is a function:
function map(func, ...)
  if select("#", ...) > 0 then
    return func(select(1,...)), map(func, select(2,...))
  end
end

--
Shmuel