On Fri 26/03/10 01:25 , Gennadiy Rozental <rogeeff@gmail.com> wrote:

Rene Rivera writes:

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Tom Brinkman wrote:

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boost::lexical_cast_no_throw()

Or..

template T lexical_cast(const S & arg, const T & error_default_value);

I've implemented later in my own version of lexical cast. In 99% of the time this is exactly what I need: either convert string to number or take this default value. Another good consequence is that I do not need template parameter anymore. Gennadiy

Looking at the various threads it seems like three different behaviours in the event of conversion failure have been requested. - Default Value - boost::system::error_code - throw custom exception. So this would suggest an interface like template< typename T , typename S, typename FailureHandler > lexical_cast(S const& arg , FailureHandler fh) with specializations if FailureHandler = T or FailureHandler = boost::system::error_code&. You do lose your "good consequence" with this formulation though. As I said in another message, the original author of lexical_cast has said several times over the years that doing something like this is too far from the spirit of a *_cast, though, so if it gets into Boost I think it will have to be in the StringConvert library.