Jeroen Habraken wrote:
Hi,
On 9 July 2011 04:10, Gordon Woodhull <gordon@woodhull.com> wrote:
Hi Vicente, all,
I've been reworking the Boost.Conversion library
Documentation: http://svn.boost.org/svn/boost/sandbox/conversion/libs/conversion_ext/doc/ht... Sandbox :http://svn.boost.org/svn/boost/sandbox/conversion/
Description: Boost.Conversion manages with generic extrinsic conversion between unrelated types. These conversion can be seen as implicit or explicit conversions.
I am excited to manage the Conversion review at the end of August.
It may be simple enough for us to say "extrinsic type-to-type conversion" since we both participated in the Boost.Convert review and have all those distinctions in mind...
But it might be confusing to potential reviewers and followers of Boost that in other "little c" conversion news this year: * lexical_cast has received a new maintainer who is adding optimizations for type-to-type which overlap with Conversion * Vladimir Batov's Boost.Convert was withdrawn. I think it's fair to Ed Diener's excellent review report [1] to say that the library was not acceptable in its current form not because it didn't have the right features, but mostly because of syntax problems. And because of confusion that its scope overlapped with lexical_cast, which I'm trying to avoid in the upcoming review! * Jeroen Habraken is working on a Boost.Coerce library [2] which does more runtime-efficient string-to-type and type-to-string conversion using Spirit.
One clear distinction is that the proposed Boost.Conversion is not concerned with the special cases of string-to-type and type-to-string. It provides a general framework for type-to-type conversion and will defer string conversions to lexical_cast or coerce depending how it is configured.
IMHO lexical_cast is not the appropriate generic function to use for type-to-type conversion (when there is no text involved), and I am managing the review to evaluate whether Boost.Conversion is the right solution.
Boost.Conversion learns from the use cases that were presented by Vladimir Batov in Boost.Convert and its review, and IIUC it now provides all the behaviors that were not string-specific, without the syntax problems. Obviously, that also means no operator<<, so there's no way to specify formatting options if text is involved. (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());
...
If there are any questions regarding Coerce, please don't hesitate to contact me either on- or off-list.
Hi, I don't see why we need to specify that the format is hexadecimal. I would expect that the spirit grammar associated to the coerce library will take care of all the formats without any specific additional tag. I see only a need for tags/manipulators when you want to convert an int to a string as you can have only one default behavior. Do you expect to have best performances with coerce than using an string stream for type to string conversions? 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.