On 12/16/11 5:54 PM, Jonathan M Davis wrote:
On Friday, December 16, 2011 16:58:51 Andrei Alexandrescu wrote:
On 12/16/11 2:58 PM, Jonathan M Davis wrote:
Unfortunately, the necessity of tzset would remain however.
Why? From
http://pubs.opengroup.org/onlinepubs/007904875/functions/tzset.html:
"The tzset() function shall use the value of the environment variable TZ
to set time conversion information used by ctime(), localtime(),
mktime(), and strftime(). If TZ is absent from the environment,
implementation-defined default timezone information shall be
used."
I'd expect a good standard library implementation for D would call
tzset() once per process instance, lazily, inside the wrapper
functions for the four functions above. Alternatively, people could
call the stdc.* versions and expect tzet() to _not_ having been
called.
That strikes the right balance between convenience, flexibility,
and efficiency.
I mean that if CTFE was advanced enough that I could do
immutable _localTime = new LocalTime();
then I could eliminate the shared static constructor for UTC
completely, but the tzset for LocalTime would still be required. It
_should_ be run once per process, and it's currently in a shared
static constructor, so that's what it does. It's just not currently
lazy. Regardless, my point was that even if CTFE were that advanced,
the static constructor would still be required. If it's changed so
that it's lazily loaded, then it can be moved out of the static
constructor, but the CTFE solution wouldn't be enough.
I'll look at what it would take to get rid of the static constructors
and make the singletons load lazily, but it will require subverting
the type system, since it's going to have to break both immutable and
pure to be loaded lazily.
I think it's all a matter of terminology. Calling tzset during module
initialization is not "required", doing it otherwise is not
"impossible", and the standard library does not have to always "play it
nice". :o)
One more thing - could you take the time to explain why you believe
calling tzset() compulsively is needed?
Thanks,
Andrei
