Re: [boost] [wave] ifndef/ifdef callbacks

From: Hartmut Kaiser (hartmut.kaiser_at_[hidden])
Date: 2006-05-14 12:45:54

Hi Felipe,

> In fact, it was easy to implement for this particular case. 
> The 'evaluated_conditional_expression()' preprocessing hook 
> now has a bool return value, which forces Wave to re-evaluate 
> the expression as long as it is 'true'. The new prototype will be:
> 
>     template <typename ContextT, typename ContainerT>
>     bool
>     evaluated_conditional_expression(ContextT const &ctx, 
>         ContainerT const& expression, bool expression_value)
>     { return false; }         // ok to continue, do not 
> re-evaluate expression
> 
> 
> Wave guarantees to keep the own state unchanged during this, 
> which means you can save the context state, change a macro 
> definition and return true to force the expression to be 
> re-evaluated. This scheme should ensure a consistent behaviour.
> 
> I'll check these changes into the CVS as soon as it will be 
> up again. It won't be part of the Boost 1.34.0 release, though.

The changes are checked into the Boost CVS::HEAD now. Please let me know if
this fits your needs now.

Regards Hartmut