[boost] Re: is_base_and_derived

From: Dave Gomboc (dave_at_[hidden])
Date: 2003-10-27 09:33:16

> > currently defined.  I think we should either change the 
> > semantics back (possibly changing the name to something
> > more appropriate if people are more comfortable with that)
> > or simply remove is_base_and_derived, unless someone can
> > come up with a compelling case for keeping it.
> 
> How about
> 
>    is_proper_supertype< B, D >   // like current is_base_and_derived
>    is_supertype< B, D >          // as above, but also true if B==D
> 
> IMO those names cleanly capture the relevent abstractions, 
> and is_supertype (which you're arguing is the commoner case, 
> and I agree) can be implemented more efficiently than 
> is_base_and_derived.
> 
> Actually I'd prefer
> 
>    is_proper_subtype< D, B >
>    is_subtype< D, B >      
> 
> but you have to be careful that you reverse the argument 
> order when changing your old code over from is_base_and_derived.

Many different forms specifying one but not the other (ancestor,
descendent, superclass, subclass, etc.) were rejected due to the ease
with which a developer could nonetheless misinterpret which argument is
supposed to go first.  (You could trawl the archives for this.)

However, I see nothing wrong with

is_base_and_derived       
is_proper_base_and_derived

Okay, I do see something wrong, they should start with "are".  But
that's also something that was hashed out a long time ago! :-)

Dave