i am deeply regretting for not responding your Question and for not posting the google summer of code Proposal . my pre semester exams are going on so i was busy in preparing which is ending on 7 may which is coming tuesday so i will be always not active during this period but i will try to respond to discussion which happening on the mailing list . i am finally sending only the proposal part . Proposal for DATE LIBRARY 1)Construction of Date: According to paper [2] there were many benchmark set but date should be represented in both ways i.e field and serial .Field and serial representation have their advantage over each other under certain operation . No invalid dates can be entered considering range cheaking ,non existent date if entered bad_date exception is thrown during the time of constructing the date. Constructing constant object for day,week_day. Date construction concrete structure <template class date_concrete> class date_pre { //year, month,week day //constructors //basic accessors declaration //conversion accessors //airthematic operation //camparison operator for date camparison } 2) Arithematic Operation On date Date airthematic can be done on three units i.e day,month,year.In chrono date ::calendar(Gregorian calendar) length of month and year is not fixed : day arithematic Adding number of days to date until range doesn’t exceed Implementing last day arithmetic to avoid the bad date excepti Eg. aug/last/2011 +months(1)= sep/30/2011 aug/31/2000 +months(1)=sep/31/2000 //invalid date bad date excep thrown month arithmetic Month arithmetic is quite complex compared to day arithmetic since number of are not fixed . (month day <=28 || month day =last day ) always add month month day =29 cheak for leap year and than add month Month day>=30 add but don’t add if resulting month is feb Using constant objects for month arithmetic. year arithematic Always add year to date considering the condition of leap year Reversal of date back to original date Usage of last day during year arithematic 3) InterConversion field representation & serial representation Some operation are quite fast on field but airthematic operation are much faster on serial campared field representation .So it is necessary to provide the inter-coversion so that it can be easily converted from one representation to another. Constructing bi-directional conversion of serial and field by making use of memoization optimization techinique. 4)Gregorian calendar implementation This Gregorian calendar will be a hybrid calendar that support both Julian and Gregorian calendar with a single discontinuity(the day on which Gregorian calendar was adopted ).The only difference between gregorian and julian is leap year calculation and before day of adoption of Gregorian calendar ,Julian calendar is implemented in this date library. The concrete draft for implementation for calendar template< typename ymd_type ,type name date _int _type > class gregorian_calendar { public : typedef ymd_type ymd _ type ; typedef typename ymd_type : : month_type month_ type ; typedef typename ymd_type : :day_type day_type ; typedef typename ymd_type : : year_type year_type ; typedef date_ int _type date_int_type ; static unsigned short day_of_week (const ymd _type &ymd ) ; static int week_number (const ymd_type &ymd ) ; static date_int_type day_number(const ymd_type &ymd ) ; static ymd_type from_day_number(date_int_type) ; static date_int_type julian_day_number(const ymd_type &ymd) ; static bool is_leap_year(year_type) ; static unsigned short end_of _month_day( year_type y ,month_type m ) ; static ymd _ type epoch() ; static unsigned short days _ i n _week(); }; 5)Building date iterator ,date output and date input Date Iterator will generate the date based on initial condition and end.Bidirectional iterator will do all the generation of series of date.Various iterators which will be implemented are day ,week ,month ,year Iterator. date output same as H. Hinnant. Questions: 1)could you explain us why do you think a class template date is a good alternative? i am using the template class since it will implement the user extensibility .This is very important feature for developer but not for normal user because developer likes to customise code it will give them to add or modify without removing features. 2) What is the expected service of the concrete classes? Which concrete representations would you provide? i have made the concrete class to show some of details of the date library which i am going to implement . <template date_concrete> class date_pre { /*year, month,week day construction of date_field i.e serial and field based reprasentation*/ /*details of constructor 1)date_pre(); //default constructor to initialise the date with the initial default value set 2)date_pre(year_type year,month_type month,day_type day); /*this constructor will initialize the date with values given by the user . but the constructor argument arrangement can be differ according to user or the country date format used */ 3)date_pre(year_type year,month_type month,week_of_month_type week_number,weekday_type wd); //this will constructs the date like monday in week 20 of 2013 4)date_pre(special day sp); //this will day construct the date with the special values like mothers day ,christmas in year //basic accessors declaration //conversion accessors //airthematic operation //camparison operator for date camparison //Coversion of calendar }; these all same as in H. Hinnant proposal except the conversion of Julian calendar to gregorian calendar . 3) How would you implement the memoizer for conversions? Would it be thread safe? Could you post an example how your date_pre and gregorian claendar classes are used? in summary, how your proposal improc-ves H.H implementation or my prototype? since pre semester are going so can i answer to this 2 question after coming tuesday ie 7 may 2013 sorry again for not answering ur questions i will try to be active on the mailing list during my pre semester xam Thanking You Shamsher Ahmed