On Wed, 11 Jul 2007 13:34:22 -0500, Martin Min wrote
Jeff: Thanks for your reply. First, by "You can use gregorian::greg_year which is the first parameter to a date", do you mean a date can be constructed by just passing greg_year? or still I have to provide a month and day?
What I mean is you can just use greg_year to represent the year instead of the date class. However, given your requirements below it probably won't be of much help.
I am working in Natural Language Understanding area, in which underspecifed Temporal Expressions abound in typical news text, and reasoning on these type of knowledge often has to deal with incomplete information. The granularity (or resolution) of time often changes in a discourse, sometimes year, or month, or date, or time, even century.
I see.
What I like most boost::date_time are the various arithematic operations on durations and date periods, and timezone support. Of course, as well as the robustness.
Probably, what I can do is to define another Date class, which have the boost::date_time::date has a member, and add members I may need?
Possibly. It seems like you might need something a bit different -- a multi-resolution time point. Or you need to have series of different time points with different resolutions. For example you could have something like this: boost::gregorian::date; //time point with 1 day resolution class month_year; //time point with 1 month resolution class quarter; //time point with 3 month resolution class year; //time point with 1 year resolution class decade; //time point with 10 year resolution class century; //time point with 100 year resolution So, simple usage would look something like: month_year my(2007, Jul); quarter q(2007, 2); year y(2007) decade d(21, 1); //21st century, 1st decade .... Of course the alternative is to have a single type that provides the something like this: //pseudo code class general_time_point { enum TIMEPOINT_RESOLUTION { DAY, MONTH, YEAR, QUARTER, DECADE, CENTURY} general_time_point(year, month, day); general_time_point(year, month); general_time_point(value, TIMEPOINT_RESOLUTION); //general constructor }; So if you had one of these 2 kinds of types, what would you like to do with them? There a conceptual issues w.r.t the meaning of arithmetic operations on these kinds of types. For example: decade c(21, 1); c += days(1); //meaningless year y(2007) y += years(2); //ok The advantage of the multi-type solution is that the meaningless operations can be prevented at compile time. However, the multi-type solution is likely more difficult in your particular case. Jeff