Re: FYI: default %printer/%destructor

[Joel E. Denny]

On Sun, 19 Nov 2006, Hans Aberg wrote:

> > Ok, I think I miscommunicated.  The ambiguity I meant is whether `b/c' is
> > the same as `b/ c' as discussed below.  `c :b' and `c:b' have the same
> > issue....
> 
> I think there should be normal tokenization the Bison .l file, with a general
> rule, stripping out space and newlines. I think this leads to the most
> intuitive grammar.

I was thinking of the human reader not Bison's scanner.

> The %destructor is only needed with output language C.

Currently, it's also useful for C++.  There could be other target 
languages some day that need it as well

> > If we use `:' for value names ...
> 
> WHat do you mean by value names, here? Is that the semantic value variables?

Yes.

> > You mean exp:r?  I don't see how that's easier.
> 
> It depends what comes first in the definition. It is easier implementing with
> defined names first, and then the definee.

I don't see how either is easier to implement than the other.

> > How do you declare that the semantic value is unused but still use the
> > location?  Will we make the gamble that this is never necessary?
> 
> I haven't considered this. Now that you mention this, I think some special
> notation might be the prudent way. The location value will probably be used
> more often with Bison improved parser diagnostics. This suggests that one
> indeed needs some special way to indicate it.

Ok, I hope you'll respond to my other email where I propose a more concise 
alternative to exp($sum, @sum).