[Python-Dev] tzset

[Tim Peters]

[Guido]
> The test passes for me on Red Hat 7.3.
>
> I tried it on Windows, and if I add "#define HAVE_WORKING_TZSET 1" to
> PC/pyconfig.h, timemodule.c compiles, but the tzset test fails with
> the error AssertionError: 69 != 1.  This is on the line
>
>             self.failUnlessEqual(time.daylight,1)
>
> That *could* be construed as a bug in the test, because the C library
> docs only promise that the daylight variable is nonzero.

That's all the MS docs promise too.  You're actually getting ord("E"), the
first letter in "EDT".

> But if I fix that in the test by using bool(time.daylight), I get other
> failures, so I conclude that tzset() doesn't work the same way on Windows
as the
> test expects.

You can read the docs.  It doesn't work on Windows the way anyone expects
<0.5 wink>:

    http://tinyurl.com/9a2n

> ...
> But is the observed behavior on Windows broken or not?  I don't know.

It probably works as documented, but Real Windows Weenies use the native
Win32 time zone functions.

> ...
> That would be acceptable to me.  Since all we want is a wrapper around
> the C library tzset(), all we need to test for is that it does that.

It's not really what I want.  When we expose highly platform-dependent
functions, we create a lot of confusion along with them.  Perhaps that's
because we're not always careful to emphasize that the behavior is a
cross-platform crapshoot, and users are rarely careful to heed such
warnings.