Migrating from ChronoKit-FP 1.6 to 2.0

ChronoKit-FP 1.6 keeps every 1.x declaration source compatible, but marks the APIs scheduled for removal in 2.0 as deprecated. Migrate while still on 1.6 so the compiler can identify remaining work. No deprecated declaration is removed in the 1.6 line.

Direct replacements#

Deprecated in 1.6	Preferred 1.6 API or action
`GetDateTime(Value)`	Use `Value` directly.
`GetAsString`	`FormatDateTime`
`FromString`	`ParseDateTime`
`RollbackMonth(Value)`	`AddMonths(Value, -1)`
`RollForwardMonth(Value)`	`AddMonths(Value, 1)`
`YMD(Value)`	`ParseDateTime(Value, 'yyyy-mm-dd')`
`MDY(Value)`	`ParseDateTime(Value, 'mm-dd-yyyy')`
`DMY(Value)`	`ParseDateTime(Value, 'dd-mm-yyyy')`
`YQ(Value)`	Parse the year and quarter, then use `StartOfQuarter`.
`DateDecimal`	`DecimalYearToDateTime`
`GetDecimalDate`	`DateTimeToDecimalYear`
`GetTimeZone`	`GetSystemTimeZoneInfo`
`WithTimeZone`	`SystemLocalToTimeZone`
`ForceTimeZone`	`TimeZoneToSystemLocal`
`GetEpiYear`	`GetISOYear` if ISO weeks are intended; otherwise use a domain calendar.
`GetEpiWeek`	`GetISOWeek` if ISO weeks are intended; otherwise use a domain calendar.

Text := TChronoKit.FormatDateTime(Value, 'yyyy-mm-dd');
Value := TChronoKit.ParseDateTime(Text, 'yyyy-mm-dd');
QuarterStart := TChronoKit.StartOfQuarter(2026, 3);
PreviousMonth := TChronoKit.AddMonths(Value, -1);

DecimalValue := TChronoKit.DateTimeToDecimalYear(Value);
Value := TChronoKit.DecimalYearToDateTime(DecimalValue);

Info := TChronoKit.GetSystemTimeZoneInfo(LocalValue);
UTCValue := TChronoKit.SystemLocalToTimeZone(LocalValue, 'UTC');
LocalValue := TChronoKit.TimeZoneToSystemLocal(UTCValue, 'UTC');

Split calendar periods from exact durations#

TDateSpanKind and TDateSpan are replaced by two representations. Use TCalendarPeriod for calendar-relative values containing years or months. Use TDuration for an exact number of elapsed milliseconds.

Deprecated in 1.6	Preferred 1.6 API or action
`TDateSpanKind`	Choose `TCalendarPeriod` or `TDuration`; no tag is needed.
`TDateSpan`	`TCalendarPeriod` or `TDuration`
`CreatePeriod`	`CreateCalendarPeriod`
`CreateDuration`	`DurationFromParts`
`AddSpan`	`AddPeriod` or `AddDuration`
`SubtractSpan`	`SubtractPeriod` or `SubtractDuration`
`SpanBetween`	`DurationBetween`, or construct a domain-specific calendar period.
`PeriodToSeconds`	Use an exact duration and read `Milliseconds div 1000`.
`SecondsToPeriod`	`DurationFromSeconds`
`StandardizePeriod`	`NormalizeCalendarPeriod`; durations need no normalization.

Period := TChronoKit.CreateCalendarPeriod(0, 1);
NextMonth := TChronoKit.AddPeriod(Value, Period);

Duration := TChronoKit.DurationFromParts(0, 2, 30);
Later := TChronoKit.AddDuration(Value, Duration);
Elapsed := TChronoKit.DurationBetween(Value, Later);
WriteLn(Elapsed.Milliseconds);

Duration constructors use checked Int64 arithmetic and raise ERangeError on overflow. They never approximate a month or year as seconds.

Move from inclusive intervals to half-open ranges#

TDateTimeRange uses [StartValue, EndValue): the start is included and the end is excluded. Equal endpoints form an empty range. CreateRange rejects a start later than its end.

Deprecated in 1.6	Preferred 1.6 API
`TInterval`	`TDateTimeRange`
`CreateInterval`	`CreateRange`
`IsWithinInterval`	`RangeContains`
`IntervalsOverlap`	`RangesOverlap`
`IntervalLength`	`RangeDuration`
`IntervalAlign`	`RangesTouch`
`IntervalGap`	`RangeGap`
`IntervalSetdiff`	`SubtractRange`
`IntervalUnion`	`TryMergeRanges`
`IntervalIntersection`	`TryIntersectRanges`

Workday := TChronoKit.CreateRange(StartValue, EndValue);
if TChronoKit.RangeContains(Workday, Candidate) then
  UseValue(Candidate);

if TChronoKit.TryIntersectRanges(First, Second, Common) then
  UseRange(Common);

Remaining := TChronoKit.SubtractRange(First, Second);
for I := Low(Remaining) to High(Remaining) do
  UseRange(Remaining[I]);

To preserve an old inclusive interval whose precision is milliseconds, create the range with OldInterval.EndDate + OneMillisecond as its exclusive end. For finer application precision, choose and document the appropriate smallest unit instead.

Replace seasonal rounding#

The duSeason enum value cannot identify a hemisphere or a meteorological versus astronomical definition. It cannot carry a Free Pascal deprecation directive, so 1.6 documents it as deprecated and raises EArgumentException when it is passed to FloorDate, CeilingDate, or RoundDate.

Use explicit domain dates. If calendar quarters are intended, use duQuarter or StartOfQuarter.

Removal list for 2.0#

ChronoKit-FP 2.0 is expected to remove every declaration named in the tables above, plus duSeason. The complete rationale and behavioural contract remain in the v1.6 API transition specification.