On 15 Jun 2007, at 18:12, Paul Eggert wrote:
Thanks for the patch that you proposed in
<http://lists.gnu.org/archive/html/bison-patches/2007-06/
msg00000.html>.
I don't use C++, so you'll have to bear with me on some dumb
questions. Perhaps some other contributor who knows C++ well can also
chime in.
* How much is this patch tied to Boost? Can it be used easily with
other
C++ libraries?
* What sort of documentation should appear in the Bison manual?
* Why is there a limitation on what types can appear? (They can't
have angle brackets, apparently.) Can this limitation be removed?
If one cannot use the type system that comes with %union, there is
not change needed: I have used a standard C++ polymorphic class
hierarchy for years. The only problem was some code placement, but
has has been fixed with the extension of %define that Akim fixed.
Akim has been thinking of variants as typed replacement of %union.
Then I think the problem is with the default actions, which no longer
can be collected to a single entry in the parser "switch" statement.
And if this part is being fixed, one can just well just introduce a
M4 macro, admitting variants as well as a standard C++ polymorphic
hierarchy, I think.
Hans Aberg
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