Re: [PATCH] more on prologue alternatives

[Paolo Bonzini]

> But the dependence on the %union position is one of the key problems I was 
> trying to eliminate.  I don't have time to examine your patch right now, 
> but, if I understand the explanation above, the only way to do the 
> equivalent of %end-header or %after-header is to have a %union.  What if 
> the user doesn't have a %union?
You place your %{...%} or %header { ... } block *after the %%*, in the 
grammar section.  Java will not use %union in fact, but it needs to have 
"%{...%}" after the %% to declare parser methods.
> Also, I'd like to see this kind of grammar organization work:
>
>   %start-header { #include "type1.h" }
>   %union { type1 field1; }
>   %destructor { type1_destroy ($$); } <type1>
>
>   %start-header { #include "type2.h" }
>   %union { type2 field2; }
>   %destructor { type2_destroy ($$); } <type2>
>
> This should be allowed in the definitions or rules section.  If you change 
> %start-header to %header under your proposal, it won't work.
>   
Yeah, I understand.  But I wonder if it warrants the needed complexity.  
In C, I put all my includes at the beginning of the file.  It gives me a 
quick way to see the interfaces I need in the file; I don't see the need 
to scatter #include's here and there in a Bison source code?

I think it is a misfeature that %{...%} works differently when you're 
using multiple-unions.  But since we have to live with it, we'd better 
make it coherent.
> Thanks for your interest in this problem.  Maybe you'd like to catch up 
> with our latest discussion starting here:
>
>   http://lists.gnu.org/archive/html/bison-patches/2006-09/msg00048.html
>   
Already read, and was lost around the end of the thread. :-)

Paolo