Re: [Boost-users] [lambda] if-then-else construct gets broken bylambda-lib

From: Sebastian Weber (sebastian.weber_at_[hidden])
Date: 2006-11-07 13:16:56

Hi Nat!

> [Nat] Does it work better if the 'else' clause is something more like:
> 
>   ( boost::lambda::bind(boost::ref(*m_wf)) )

Well, not really. If I do that, I get the error.

error: no match for ternary 'operator?:' in '(sIndex <
(((boost::cor_cm_iterator4<RandomGenerator,
Graph>*)this)->boost::cor_cm_iterator4<RandomGenerator,
Graph>::m_maxIndex + 1)) ?
boost::lambda::bind(boost::ref(((boost::cor_cm_iterator4<RandomGenerator, Graph>*)this)->boost::cor_cm_iterator4<RandomGenerator, Graph>::m_cf), minDeg, boost::lambda::<unnamed>::_1) : boost::lambda::bind(boost::ref((*((boost::cor_cm_iterator4<RandomGenerator, Graph>*)this)->boost::cor_cm_iterator4<RandomGenerator, Graph>::m_wf)))'

> ? This is a wild guess, but boost::ref() isn't by itself a lambda bind
> expression -- is it? Both halves of the ternary operator are convertible
> to boost::function -- but they're not the same type.
> 
> I don't know whether two different boost::lambda::bind expressions are
> going to be compatible either. You may have to explicitly instantiate
> boost::function objects on both sides of the : -- which would end up
> being less terse than writing the if/else statement. But it seems worth
> a try.

I actually have no clue. Nevertheless, I'm already very happy to have
written my first lambda-stuff without struggling to much with it - it is
quite a magic thing to get it working for a beginner. Anyway thanks for
your response.

Greetings,

Sebastian

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