Re: [boost] Convert library -- Andrzej's review

Vladimir Batov writes:

Andrzej Krzemienski writes:

...

I personally do not like this trick to force me to type this "from" in "convert<int>::from".

It's been a while and OTOH I do not remember what/how it was exactly but the main purpose of "from" is to separate TypeIn from TypeOut. Not

template optional<TypeOut> convert(TypeIn, Converter)

but

template<class TypeOut> struct convert { static optional<TypeOut> from(TypeIn, Converter); }

That way (at least I felt so back then) it was the only way to provide the ability to *reliably* specialize separately on TypeIn and/or TypeOut. Again, maybe that original decision/design is not valid or important and needs to be revisited.

I just had another look and there seems no value anymore in potential specializations on TypeIn, TypeOut. It's because all the "smartness" and type-handling has been moved to converters. So, *there seems*, the "from" can be dropped. That is, int v = boost::convert<int>(str, cnv).value(); instead int v = boost::convert<int>::from(str, cnv).value(); and std::transform( strings.begin(), strings.end(), std::back_inserter(integers), convert(ccnv(std::hex)).value_or(-1)); instead std::transform( strings.begin(), strings.end(), std::back_inserter(integers), convert<int>::from<string>(ccnv(std::hex)).value_or(-1)); I am on the fence (the "from" has been with me for some time). Any strong/weak :-) preferences, any for/against arguments?