Re: Syntax request (coming to terms with false)

[Tom Wrensch <twrensch@...>]

On Thu, 17 Jan 2002 RLake@oxfam.org.uk wrote:

> 
> OK, I'm trying to come to terms with false. I've started going through my
> code looking for places where I assign the result of a boolean expression
> to a table expecting nil to delete the key (since false will no longer do
> that). Maybe I'm the only person with this problem.
> 
> if t = function_which_might_return_false(x) then
>      a[x] = t
>   else
>      a[x] = nil
> end

This, at least, could be made less painful with a function that converts
false to nil, similar to what you were discussing with the
? operator. Thus:

function ftn(x) -- False to Nil function
    if x==false then
	return nil
    else
        return x
    end
end

You example then becomes:

    a[x] = ftn(function_which_might_return_false(x))


You may need to make other versions when you want to handle multiple
return values of course, though I find I rarely use them.

  - Tom Wrensch