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Added notes about epochs, the year 2038, and a small Y2K disclaimer

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(all with index entries!).  Also update the list of functions that
take or yield a time represented as a 9-tuple.
This commit is contained in:
Guido van Rossum 1998-06-09 21:25:41 +00:00
parent dd47ec98e2
commit 929bd0e02e
1 changed files with 19 additions and 4 deletions
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23
Doc/lib/libtime.tex
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@ -13,7 +13,21 @@ An explanation of some terminology and conventions is in order.
The \dfn{epoch}\index{epoch} is the point where the time starts. On
January 1st of that year, at 0 hours, the ``time since the epoch'' is
zero. For \UNIX{}, the epoch is 1970. To find out what the epoch is,
look at \code{gmtime(0)}.
look at \code{gmtime(0)}.%
\index{epoch}
\item
The functions in this module don't handle dates and times before the
epoch or far in the future. The cut-off point in the future is
determined by the C library; for \UNIX{}, it is typically in 2038.%
\index{Year 2038}
\item
Year 2000 (Y2K) issues: Python depends on the platform's C library,
which generally doesn't have year 2000 issues, since all dates and
times are represented internally as seconds since the epoch.%
\index{Year 2000}%
\index{Y2K}
\item
UTC is Coordinated Universal Time (formerly known as Greenwich Mean
@ -48,8 +62,9 @@ nonzero fraction (\UNIX{} \cfunction{select()} is used to implement
this, where available).
\item
The time tuple as returned by \function{gmtime()} and
\function{localtime()}, or as accpted by \function{mktime()} is a
The time tuple as returned by \function{gmtime()},
\function{localtime()}, and \function{strptime()}, and accepted by
\function{asctime()}, \function{mktime()} and \function{strftime()}, is a
tuple of 9 integers: year (e.g.\ 1993), month (1--12), day (1--31),
hour (0--23), minute (0--59), second (0--59), weekday (0--6, monday is
0), Julian day (1--366) and daylight savings flag (-1, 0 or 1).
@ -99,7 +114,7 @@ Nonzero if a DST timezone is defined.
\begin{funcdesc}{gmtime}{secs}
Convert a time expressed in seconds since the epoch to a time tuple
in UTC in which the dst flag is always zero. Fractions of a second are
ignored.
ignored. See above for a description of the tuple lay-out.
\end{funcdesc}
\begin{funcdesc}{localtime}{secs}