Re: trying out the c++ parser skeleton / b4_post_prologue

[Hans Aberg]

On 11 Jul 2006, at 17:29, Joel E. Denny wrote:

> On Mon, 10 Jul 2006, Anthony Heading wrote:
>
> > The right point appears to be the b4_post_prologue macro,
> > but bizarrely this seems to be inaccessible unless the
> > parser uses %union.
>
> Thanks for the feedback.  We've been debating how to clean this  
> behavior
> up.

  http://www.wsu.edu/~brians/errors/churchill.html

>   A solution is actually implemented in CVS, but I'm not sure if that
> one will stick.  You should see some sort of solution in Bison 2.4.

> > As proof-of-principle, I created a new directive (naturally
> > called "%no-union"!) which only flipped the prologue.  That
> > seemed to work OK, but I wonder if there's a better solution?

The developers are currently settling for very simple C++, and there  
is little chance you will be able to do normal C++ code writing via  
Bison 2.4 or whatever.

There is an experimental %define directive which can be used to place  
C++ code correctly, some time in the future when it can be used to  
place code, except for 1-liners. So you (Anthony Heading) are on  
right track: one needs a way to place code more accurately in order  
to do C++. In fact, I have made my own tweaks of Bison for last  
couple of years in order to place the C++ code correctly. :-) But I  
got tired of patching up the many frequent Bison releases, so I am  
currently stuck with Bison 2.0.

And when you use %union, the underlying C++ implementation must  
currently be untyped, not something that one would use in ordinary C+ 
+ programming.

  Hans Aberg