boolean true and false values.

[Tim Rowe]

In article <8j7n6h01tnl at news2.newsguy.com>, alex at magenta.com (Alex 
Martelli) wrote:

> Tim Rowe <digitig at cix.co.uk> wrote in message
> news:memo.20000625230712.5257C at digitig.compulink.co.uk...
>     [snip]
> > > Yes, I know, but why is it not in the language ?
> > > Quite a lot of algorithms rely on having sets. If you put them in a
> > > list, there
> > > is an order which is not always wanted.
> >
> > There is always an order, but you don't always know what it is. When 
> > you
> > write your set class you just document that if the user iterates over 
> > the
> > elements then the order in which they will be returned is undefined --
> > that's what happens in the C++ STL. The fact that the implementation 
> > has a
> 
> Good general concept, un-good specific example.  C++'s std::set 
> (originally
> inspired from STL) is based on an ordering relationship, and when you
> iterate
> from .begin() to .end() you get the elements in increasing order 
> according
> to
> just that relationship.  The current release of STL also has hash-based
> containers (which didn't make it into the C++ standard library), but the
> standard ones are sorted...

Oh well, at least I had the right idea!