Re: DSSSL extensions for XSL

[James Clark <jjc@xxxxxxxxxx>]

Frank Christoph wrote:
> 
> > > > Is an upwards-only call/cc very valuable.
> > >
> > > It's useful for all things you would use return/break/continue for in C,
> > > Java or JavaScript.
> > >
> > > > I know that it can be used to
> > > > implement exception handling, but I think it may be more confusing than
> > > > helpful. A catch/throw special form might be more appropriate. Are there
> > > > other uses of an upwards-only call/cc?
> 
> What "upwards-only" call/cc is supposed to denote?  I'm aware of something
> similar to "downwards-only" call/cc, namely the so-called call/ec
> (call-with-escaping-continuation).  This might be called downwards-only
> because the continuation can be passed down, but not up and out of the
> protected expression.  Is this what you mean?

An upwards-only continuation is one that can only be used to return to a
stack frame in the current call chain. When the call/cc call that
created a continuation has returned, the continuation can no longer be
called.

James


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