Re: nil isn't as unique in Lua 4.1

[David Jeske <jeske@...>]

On Thu, Jan 10, 2002 at 12:37:35AM -0500, Peter Shook wrote:
> I'd rather not have the boolean type because then there will be a need
> for functions like Perl's 'defined' (to tell if a variable is not nil)
> and 'exists' (to tell if a table has a value for a particular key).  How
> else with you be able to tell if a variable is false or nil?

We could introduce a new operator to replace the overloading of
"or". Something like "ond" (On Not Defined):

  nil  or    2 -> true
  nil  ond   2 -> 2

  false or  2   -> true
  false ond 2   -> false

  nil or false  -> false
  nil ond false -> false

This seems better than having to do this all the time:

  a= if defined(b) then b else c end

However, don't get me wrong, I'll take any pain required if it means I
can actually store a false value in a table. Currently I have to make
EVERY if statement look like "if expr ~= 0", just so I can store 0
(i.e. false) values in a table.

-- 
David Jeske (N9LCA) + http://www.chat.net/~jeske/ + jeske@chat.net