Re: [boost] [convert] no-throw and fallback feature

Subject: Re: [boost] [convert] no-throw and fallback feature
From: Vicente BOTET (vicente.botet_at_[hidden])
Date: 2011-05-08 07:41:49

> Message du 08/05/11 12:57
> De : "Vladimir Batov" 
> A : boost_at_[hidden]
> Copie à : 
> Objet : Re: [boost] [convert] no-throw and fallback feature
> 
> > From: "Vicente BOTET" 
> > Hi,
> >
> > I was thinking on the fallback feature a little bit more and I've the
> > impression that we can get it for free. If we accept that we need a 
> > no-throw
> > function such as try_convert_to that returns an optional Target we can 
> > have
> > the fallback using the optional::get_value_or function
> >
> > auto r = try_convert_to(*int*)(s);
> > int i = r.get_value_or(fallback);
> > ...
> > I don't know if it is worth adding a function that does all in one
> >
> > int i = convert_to_or(*int*)(s, fallback);
> 
> Vicente,
> 
> Your suggestion of deploying get_value_or() indeed provides the fallback 
> feature quite easily. However, the original 2 args function
> 
> Target v = convert_to_or(s, fallback);
> 
> does that and more. :-) It does not require the Target type to be 
> DefaultConstructible. Something dear to my heart. :-)

You are right, convert_to_or can be specialized for non default constructible types and could even perform better. What others think of the naming and signatures? 

Best,
Vicente