0cfa783b14
* Many of the ideas and some of the code herein is credited to Adrian Colomitchi * Decouple fractional decimal seconds formatting from time_of_day formatting so that it can be more easily used elsewhere in the future. * Include super-second durations such as nanocenturies and microfortnights in the class of durations that will get formatted with fractional decimal seconds. * If a duration is exactly representable with fractional decimal seconds not exceeding 18 decimal fractional digits, format it exactly. Otherwise format it to 6 fractional decimal digits (microseconds precision). The number 18 is chosen as this is the limit of std::ratio using 64 bits (i.e. atto). * The above bullet implies that durations with ratio<1, 4> will now be formatted with 2 fractional decimal digits instead of 1. ratio<1, 8> will be formatted with 3, and ratio<1, 3> with 6. * Unify the implementation into one C++11 implementation that works equally well with C++14. * Drive-by fix a couple formatting bugs dealing with negative durations. * Deprecate the make_time functions taking unsigned md by removing their documentation. Also deprecate the corresponding time_of_day constructors taking unsigned md. * This change paves the way for future formatting improvements.
IMPORTANT UPDATE:
Recently IANA changed how they reported the database version. If you have AUTO_DOWNLOAD enabled in the tz library, you must update to include this commit:
Without this update your tz lib will download a new copy of the database everytime you start your program.
_**[Try it out on wandbox!](http://melpon.org/wandbox/permlink/PodYB3AwdYNFKbMv)**_
This is actually several separate C++11/C++14 libraries:
-
"date.h"is a header-only library which builds upon<chrono>. It adds some newdurationtypes, and newtime_pointtypes. It also adds "field" types such asyear_month_daywhich is a struct{year, month, day}. And it provides convenient means to convert between the "field" types and thetime_pointtypes. See http://howardhinnant.github.io/date/date.html for more details.Here is the Cppcon 2015 presentation on date.h: https://www.youtube.com/watch?v=tzyGjOm8AKo
Here are the Cppcon 2015 slides on date.h: http://schd.ws/hosted_files/cppcon2015/43/hinnant_dates.pdf
-
"tz.h"/"tz.cpp"are a timezone library built on top of the"date.h"library. This timezone library is a complete parser of the IANA timezone database. It provides for an easy way to access all of the data in this database, using the types from"date.h"and<chrono>. The IANA database also includes data on leap seconds, and this library provides utilities to compute with that information as well. See http://howardhinnant.github.io/date/tz.html for more details.Here is the Cppcon 2016 presentation on tz.h: https://www.youtube.com/watch?v=Vwd3pduVGKY
Here are the Cppcon 2016 slides on tz.h: http://schd.ws/hosted_files/cppcon2016/0f/Welcome%20To%20The%20Time%20Zone%20-%20Howard%20Hinnant%20-%20CppCon%202016.pdf
-
"chrono_io.h"is a header-only library for streaming out chrono durations. See http://howardhinnant.github.io/date/chrono_io.html for more details. -
"iso_week.h"is a header-only library built on top of the"date.h"library which implements the ISO week date calendar. See http://howardhinnant.github.io/date/iso_week.html for more details. -
"julian.h"is a header-only library built on top of the"date.h"library which implements a proleptic Julian calendar which is fully interoperable with everything above. See http://howardhinnant.github.io/date/julian.html for more details. -
"islamic.h"is a header-only library built on top of the"date.h"library which implements a proleptic Islamic calendar which is fully interoperable with everything above. See http://howardhinnant.github.io/date/islamic.html for more details.
There has been a recent change in the library design. If you are trying to migrate from the previous design, rename day_point to sys_days everywhere, and that ought to bring the number of errors down to a small roar.
"date.h" and "tz.h" are now being proposed for standardization: http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0355r1.html