Generic FunctionPackage: util.date-timeToCDocOverviewCGDocRelNotesFAQIndexPermutedIndex
Allegro CL version 9.0
Unrevised from 8.2 to 9.0.
8.2 version

date-time-ywd-before-year-0

Arguments: date-time

Returns the value of the ymd-yd-before-year-0 of date-time, which must be a date-time object. The value can be t or nil. t means the date in date-time is definitely before the year 0. nil can mean that the date is not before the year 0 or that the slot value has not been calculated and holds its initial value (which is nil).

The value depends on the value of the ywd-century (reader date-time-ywd-century: if that value is positive, the century is not before year 0 and so nil is the proper value for this function; linewise the century being negative means t is the correct value for this function. If the value of the ymd-yd-century is nil, the correct value for this function cannot be determined and the initial value (nil) is returned.

date-time should be complete (see complete-date-time) before calling this function. Otherwise the slot may be unset even though there is enough date information to set it accurately.

This is not a particular useful value for user code (its is useful for internal code). Users may wish to just look at the century value to determine whether the date is before year 0 or not, if that information is knowable. See also date-time-ymd-yd-before-year-0, which give a different value on January 1, year 0.

See date-time.htm for information on support in Allegro CL for parsing and generating time expressions using the ISO 8601 standard.


Copyright (c) 1998-2012, Franz Inc. Oakland, CA., USA. All rights reserved.
Documentation for Allegro CL version 9.0. This page was not revised from the 8.2 page.
Created 2012.5.30.

ToCDocOverviewCGDocRelNotesFAQIndexPermutedIndex
Allegro CL version 9.0
Unrevised from 8.2 to 9.0.
8.2 version