Hartmut Kaiser wrote:
On Jul 9, 2011, at 2:52 AM, Jeroen Habraken wrote:
On 9 July 2011 04:10, Gordon Woodhull <gordon@woodhull.com> wrote:
(Jeroen, if you're reading this, can you convert to/from e.g. hexadecimal with Coerce?)
It isn't possible at the moment but it is to be re-added during the Google Summer of Code. The syntax will probably look something like coerce::as<int>("0x17", tag::hex());
Aha, that's why I asked. Not currently compatible with Boost.Conversion: just as there's no way to supply iostream manipulators for Convert-style formatting, there's no way to supply tags for Coerce- style.
Vicente, do you have any thoughts on whether extra parameters could be added generically?
I don't think that these kind of specific conversions could be added to simple type-to-type conversions. As I signaled during the Boost.Convert review I will use instead an auxiliary string stream and output and input the types we want to convert using as many manipulators as the user wants.
I have added an example here http://svn.boost.org/svn/boost/sandbox/conversion/libs/conversion_ext/exam ple/formatted.cpp that shows how I will apply these kind of conversions. As you can see this example doesn't make use of the Boost.Conversion generic functions when manipulators are needed. Instead it uses either a template io stream (extractor_stream) that is able to extract the type given as parameter when the extract manipulator is used or a io stream ( via_stream) that is able to extract any type given as parameter of the manipulator extract_to.
This might be off topic and purely esthetical (i.e. personal taste), but I find the mix of operator>>() and operator<<() in the same expression to be more than confusing. That's (for me) clearly not a viable solution.
I agree with you that the mix of i/o operators could be confusing. Maybe it could be less confusing if we write them as follows std::string si2 = ii =>> std::uppercase =>> std::hex =>> via_stream() >> extract_to(*std::string*)(); If I'm not wrong =>> is left to right associative, so the preceding is equivalent to (ii =>> (std::uppercase =>> (std::hex =>> via_stream()))) >> extract_to(*std::string*)(); Note that I'm not proposing to include this on Boost.Conversion. Best, Vicente -- View this message in context: http://boost.2283326.n4.nabble.com/Boost-Conversion-pre-review-request-tp365... Sent from the Boost - Dev mailing list archive at Nabble.com.