Re: [Boost-users] [Proto] implementing an computer algebrasystemwith proto

Subject: Re: [Boost-users] [Proto] implementing an computer algebrasystemwith proto
From: Dave Jenkins (david_at_[hidden])
Date: 2009-01-28 10:55:30

"Eric Niebler" <eric_at_[hidden]> wrote in message 
news:49807DB5.2080307_at_boost-consulting.com...
> You're passing an expression to a grammar to be evaluated with its 
> transforms. That expression must match the grammar. It's undefined 
> behavior if it doesn't, and in this case, it doesn't. "Performing the 
> transform" falls withing UB.
>
> It would be possible to add a compile-time check to all grammars function 
> call operators to catch this error, but that comes with a compile-time 
> cost.

I think it would be a useful check.  Could you either
(1) always check in proto::exact
(2) check when a compile time flag is defined