Atomicity of builtins (was: Weakdictionary diffs)

[Raphael Collet]

Raphael Collet wrote:
> 
> 2. Suggested strategy
> 
> Kevin and I suggest to keep things safe.  Some real bugs have been fixed
> recently.  Let us keep the other changes for after the release.  The
> packaging process is much more important.

Just to make things clearer: I have added two builtins for weak
dictionaries, namely 'exchange' and 'condExchange'.  Those builtins are
not implemented as functions, they explicitely unify their second last
argument to their output.  (Their last argument is the new value, the
second last is the old value.)

I have been suggested to modify the existing 'exchange' builtins to
follow the same convention as mine.  But Kevin and I think we should not
do these changes before the release.


Cheers,

raph