Re: Returning nil vs returning nothing

[nobody <nobody+lua-list@...>]

(written without access to a Lua interpreter, bugs unlikely but possible)

  local function xpack( x, ... )
    return x, table.pack( ... )
  end
  function suppress( f, ... )
    local _, rets = xpack( pcall( f, ... ) )
    return table.unpack( rets, 1, rets.n )
  end

-- nobody

On 27/10/2020 20.25, Grzegorz Krasoń wrote:
> Function that returns nothing seems different than function that returns 
> `nil`:
>
> ```lua
> function f()
>      return nil
> end
>
> function g()
> end
>
> print(f()) -- prints nil
> print(g()) -- prints empty line
> ```
>
> How to recognize this at the function call? For example how to implement 
> an universal wrapper that would suppress all errors and still returns 
> exactly the same thing as wrapped function in case of success?
>
> ```lua
> function supperess(f, ...)
>      success, result = pcall(f, ...)
>      return result
> end
>
> print(supperess(f)) -- prints nil
> print(supperess(g)) -- also prints nil, how to fix it?
> ```