RE: [boost] Quick comments on tuples

From: Gary Powell (Gary.Powell_at_[hidden])
Date: 2001-06-18 12:18:18

[snip]
> [Daryle Walker]
> 2.  There's a type called "nil" for a placeholder for unused positions.
> This is confusing from the usage as a NULL pointer that the last reviewed
> library had.  The name should be more descriptive.  Worse, the name "nil"
> is a macro constant in at least one OS-provider's system headers.
> [Gary]
> I've been following the function::nil issues and would like to use a
> boost::nil/null (whatever) as a replacement for tuples::nil. Tuples just
> need a unique type, no value or conversion operators are necessary. And
> there is no point in having a function::null and a tuples::null.
>
> Thanks again, and I would have modified the tuples submission but no firm
> resolution on function::nil is out yet.

[Douglas McGregor]
Nil (null) will not be included in function at this time. It is too 
controversial to sneak in as part of 'function' (if we were all U.S. 
Congressmen things would be different...). 

Tuples appears only to need a sentinel type. I'd suggest 'null_type' to
avoid 
any collisions with MacOS, and move it into a detail namespace.

I'll reintroduce the notion of a generalized 'null' again after I have had 
more experience with it.
[Gary]
Going to "null_type" would be fine. It's not a detail, so moving it to an
implementation detail namespace would be a mistake. We'll add some
documentation for its use. (LL uses it.) Then if boost ever has a
boost::null we can switch to that.

  Thanks for the comments.

  Yours,
 -gary-