Re: FYI: default %printer/%destructor

[Joel E. Denny]

On Tue, 21 Nov 2006, Paul Eggert wrote:

> "Joel E. Denny" <address@hidden> writes:
> 
> > I suspect that using [] in a grammar to mean optional is not nearly as 
> > common.
> 
> It's pretty common, I'm afraid.  It's in the ISO standard for EBNF,
> for example.
> 
> http://www.cl.cam.ac.uk/~mgk25/iso-ebnf.html
> 
> Characters unused by ISO EBNF include .:!+_%@&#$<>/\^`~.

Ok, thanks.  Nevertheless, surely it's not as common as () used for 
grouping.  And it's still not clear to me what's wrong with "(...)?" 
instead of "[...]".

> I sort of liked the notation a.b to denote the b component of a, as
> it's a common notation in many languages.  But I admit I haven't been
> following this discussion too closely.

Are you referring to this?

  exp.sum: exp.term1 '+' exp.term2