[antlr-interest] Lexer and Parser class packaging

[Gavin Lambert]

At 10:49 6/02/2007, Terence Parr wrote:
 >
 >So @members {int i;} should also code to both parser and lexer.
 >Which makes you feel more uncomfortable? the inconsistency or 
the
 >fact that @header doesn't go to both? ;)

Inconsistency is simply inexcusable, so I guess that makes me the 
most uncomfortable :)

But I was also proposing a third option: making unqualified 
@header sections illegal.  That's what I actually prefer over 
sending it to both, if I had to choose one.

In my ideal world, you'd have the following constructs:

@lexer::header {}         => written to lexer only
@parser::header {}        => written to parser only
@lexer,parser::header {}  => written to both
@header {}                => special case

... where the unqualified version is accepted if only one of the 
two are being generated (eg. only parser rules are supplied, or 
it's specified as a 'lexer graamar' or 'parser grammar'), and 
generates an error otherwise.  Or maybe just generates a warning 
and then writes it to both.  I don't think it should quietly write 
it to both and I definitely don't think it should write it to only 
one if multiple files are being generated.

The same holds true for @members, and @footer (if such a thing 
exists, and if not, it should, so that you can do namespaces in 
C++, among other things).  They all need to be consistent.