Re: FYI: default %printer/%destructor

[Hans Aberg]

On 21 Nov 2006, at 19:59, Joel E. Denny wrote:

> > I think that all that makes the grammar rues harder to read should be
> > avoided.
>
> Yes, more information will always do that.
>
> > Also, it is good if the user as far as possible
> > can avoid writing repetitions.
>
> So, something like:
>
>   a(name1): b c() d(name2[@,#]) e(name3[$,#,%])
>
> Still ugly, but I like it better than ($#%name), which looks like  
> one long
> cryptic variable.

I do not know. Perhaps use "{}" instead of "[]", to indicate it is  
sets, if not conflicting with action "{}".

One idea I am playing around with is a header/source breakup. The  
actions would then be put in the source (or in a separate segment),  
and the rules in the header. One motivation is to make the grammar  
readable in the case of complicated actions. Another is that if only  
the actions are altered, Bison needs not recompute the parser states.

The main problem is how to avoid having to write the grammar rules  
more than once.

> Well, I think we're getting ahead of ourselves.  The notation I've
> proposed seems to cleanly accommodate what we need now.  I think  
> there are
> several possible ways to extend it if necessary in the future.

As long as it does not close any doors, if some of the other stuff  
needs to be implemented, whatever it may be.

  Hans Aberg