ICU API Proposal: new fields in Calendar, change to getActualMaximum()

Expiration: Thursday, Nov 13, 2003

**** Item #1 - getActualMaximum()
Motivation: Calendar vs. GregorianCalendar is inconsistent

in ICU 2.6,  some C++ enums  such as Calendar::EDateFields  were 
deprecated and replaced with the C enums, even in the C++ API.	In the 
base Calendar API this function was added:

	int32_t Calendar::getActualMaximum(UCalendarDateFields field, 
UErrorCode& error);

Calculating the actual maximum of a field can involve a lot of 
processing, some of which can generate errors.

However, the subclass GregorianCalendar had this API (marked draft 2.6)

	int32_t GregorianCalendar::getActualMaximum(UCalendarDateFields field);

This error hid the base getActualMaximum function from users of the 
subclass.

I propose to remove the 
GregorianCalendar::getActualMaximum(UCalendarDateFields) interface, and 
replace it with one with the status code, as in the base class:

	int32_t GregorianCalendar::getActualMaximum(UCalendarDateFields field, 
UErrorCode& error);


**** Item #2 - new fields
Motivation: To complete the port from Java, I am adding three new 
fields.  Descriptions are below, from the javadoc.

   /**
    * Year of this calendar system, encompassing all supra-year fields. 
For example, in Gregorian/Julian calendars, positive Extended Year 
values indicate years AD,  1 BC = 0 extended, 2 BC = -1 extended, and 
so on.
    * @draft ICU 2.8
    */
   UCAL_EXTENDED_YEAR,

   /**
    * Modified Julian day number, encompassing all date-related fields.  
Demarcates at local midnight.
    * @draft ICU 2.8
    */
   UCAL_JULIAN_DAY,
   /**
    * Ranges from 0 to 23:59:59.999 (regardless of DST).  This field 
behaves <em>exactly</em> like a composite of all time-related fields, 
not including the zone fields.  As such, it also reflects 
discontinuities of those fields on DST transition days.  On a day of 
DST onset, it will jump forward.  On a day of DST cessation, it will 
jump backward.  This reflects the fact that is must be combined with 
the DST_OFFSET field to obtain a unique local time value.
    * @draft ICU 2.8
    */
   UCAL_MILLISECONDS_IN_DAY,


Also,   UCAL_DAY_OF_MONTH will be added as an alias to UCAL_DATE, for 
compatibility with Java.

Furthermore,  Calendar::FIELD_COUNT will be an alias to 
UCAL_FIELD_COUNT so that  Calendar::FIELD_COUNT will be correct, even 
though there are not C++ enums for the new functions.