Re: Readability question.

Hello Martin.

On Fri, 5 Jun 2026 at 19:06, 'Martin Eden' via lua-l
<[email protected]> wrote:
> On 2026-06-05 16:11, Francisco Olarte wrote:
> It still bad for me:

"Para gustos los colores", we say around here. But I'll try to spain.

>    if a == nil then
>       return b
>    end
>    if b == nil then
>       return a
>    end
> We're testing for one thing and returning other.

Which is typical when testing for "badness", I read this as "if a is
bad, use b, if b is bad, use a, if both are good, use both". It lacks
an "if both are bad" at the start, which I could use too, but it is
not relevant in this case. In fact every usage of 'return a and b',
'return a and b or c', even 'return a or b' depending on how yoou look
at it, tests one thing and return ( or uses if you are doing a
parameter pass or assignment ) other.

 For the full version I would use
if (a==nil) then
  if (b==nil) then
    return --nothing.
  else
    return b
  end
else -- elseif would avoid a nesting level, but spoil symmetry, as
would collapsing elses above.
  if (b==nil) then
    return a
  else
   return f(a,b) --both
  end
end

Anyway, the way I code it reflects a bit my assembly origins, and my
distate for too much nesting. For a C-style block delimiters I would
probably code the first two ifs as one-liner, but with then-end style
I nearly never use it. Now that I see it I  may switch to
if a==nil then if b==nil then return else return b end end

I tested some, and liked how the byte code reflected the source style,
this is why I used that. But I have to stop playing with byte code or
I will write byte-assembler just to scratch the itch caused by the
unsuppressed redundant function end returns.

> I think I would settle at
>
> local function safe_calc(f, a, b)
>    return
>      function(a, b)
>        if not (a and b) then return (a or b) end
>        return f(a, b)
>      end
> end

Yep, classical else avoidance, one liner for simple guard conditions.
I do it that a lot, for speed sometimes ( I have a hard time
remembering I'm not on a 8080 anymore ), but, lacking an optimizer,
this evaluates too much. Granted, lua seems to not have an opcode for
==nil and makes a constant and to hold it, but I like how my version
compiles, and the nearly minimal set of ops. But they are all the same
at the end.

Francisco Olarte.

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