Re: false [was: The "Is nil present in a table" problem}

["Paul Chakravarti" <pc000@...>]

Edgar Toernig writes:
> > >> (http://lua-users.org/wiki/BooleanTypeProposal) 
> >
> > I had a slight question/concern with the following - 
> >
> >  -- Relational operators return false for false and a value other than
> >  -- false/nil for true
>
> In fact, they always return the number 1 for true.  Maybe it's better
> to say that explicitely (and define true to be 1).  That way 
>
>    (a==b) == (c==d) 
>
> and alike becomes valid. 

I would prefer that this explicitly evaluated to a distinct 'true'
type - if there is no explicit 'true' value it is impossible to
correctly serialise the value for an API which expects a destinct
boolean value (in this case specifically XMLRPC but generally true) by
checking the type. 

eg. { aaa = true|false } will be serialised as a boolean if false
(as this is a distinct type) but as an integer if true & true is
represented as "1". 

This could be fixed by explicity casting to a user type but this is
somewhat ugly. 

> And then define that if/while/not/... only accept 'false' and 'true'?
> I thought about it myself but IMHO it complicates things more than
> it would help. 

I dont think that this is necessary - all non nil/false values can
still be treated as true - this is just a specialisation of the
inplementation to include a 'true' class which is returned by
relational operators (and can be explicitly assigned) - I dont think
that this changes the semantics at all just makes it easier to detect
boolean values for code that requires this (relational opeartors still
return a non-nil value as per the current implementation - this non-nil
value just happens to have a type of 'true') 

Regards, PaulC