ISTR that we force the epoch to be 1970 on all major platforms -- or perhaps it happens to be 1970 even on Windows when using MS's C runtime.
On Mon, Jun 16, 2008 at 4:08 PM, Curt Hagenlocher <[EMAIL PROTECTED]> wrote: > The documentation for the time module says that "the 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 gmtime(0)." This confirms that the epoch is > platform-specific. As such, the only legal uses of the timestamp should be > > 1) comparing with another timestamp to determine elapsed time in seconds > 2) passing to another standard Python library function which expects a > timestamp > 3) as a source of randomness. > > However, the following files in the standard library have hardcoded the > assumption that the Python epoch will always be the same as the Unix epoch: > In gzip.py, method GzipFile._write_gzip_header > In tarfile.py, method _Stream._init_write_gz > In uuid.py, function uuid1 > > Additionally, the following files in the standard library have hardcoded the > assumption that the Python epoch will cause timestamps to fall within the > range of a 32-bit unsigned integer value: > In imputil.py, function _compile > In py_compile.py, function compile > > So there's some kind of a potential discrepancy here, albeit a minor one. > This discrepancy can be resolved in one of at least three ways: > > 1) The documentation for the time module is wrong, and the epoch for Python > (at least versions 2.x) should be the Unix epoch. > 2) These library functions are slightly wrong and should be modified by > subtracing an "epoch offset" before doing other calculations. This offset > can be calculated as "time.mktime((1970, 1, 1, 0, 0, 0, 3, 1, 0)) - > time.timezone". > 3) These library files should be considered part of the platform-specific > implementation, and an alternate platform should provide its own version of > these files if necessary. > > Any thoughts on this? > > From the perspective of implementing IronPython, I'd prefer that the answer > is 1 or 2 -- but mainly I just want to be as compatible with "the spec" as > possible, while respecting CLR-specific norms for functionality which is > left up to individual implementations. > > -- > Curt Hagenlocher > [EMAIL PROTECTED] > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > http://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > http://mail.python.org/mailman/options/python-dev/guido%40python.org > > -- --Guido van Rossum (home page: http://www.python.org/~guido/) _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
