Surprising result from %s format

[barefootcoder]

Okay, I figure I've got about a 50/50 shot of this one being considered a bug. :-)

[absalom:~] perl -MTime::Piece -le 'print gmtime(1000000000)->strftime("%s")'
1000028800

Now, the evidence that this isn't a bug is this:

[absalom:~] perl -MPOSIX -le 'print strftime "%s", gmtime(1000000000)'
1000028800

So, on the one hand, Time::Piece::strftime is just doing the same thing that POSIX::strftime is. On the other hand, it's a pretty non-intuitive result. :-)

The problem, of course, is that the underlying strftime is just receiving a structure of the individual time values, and has no concept of whether it's local time or UTC. But, as a counterpoint, a Time::Piece object does know whether it's local or UTC, so I think there's a reasonable argument to be made that Time::Piece::strftime ought to be smarter than POSIX::strftime.

So, one option is to pre-handle %s in a format string similar to how it currently does for %z and %Z:

    $format =~ s/%s/$time->epoch/eg;

It's a fairly simple change, but of course it does constitute a definite change in behavior. I can't imagine anyone who would actually be counting on the existing behavior, but maybe there is someone somewhere.

So another alternative would be just to document the weirdness, perhaps in the "CAVEATS" section of the POD. (We could add a new subsection for strftime and also mention #23, even.)

If either of these seems like a good idea to anyone, I'm happy to submit a patch for whichever gains the concensus.

[smith153]

Someone added a test case that was failing because of this :)

What I am doing right now is just parsing out the %s before hand and replacing it with an epoch that is calculated on class instantiation.

There was also a problem within strptime. The epoch was only passed to gmtime (in C) and never tp localtime. I fixed that as well. I think..still testing though.

On my local american machine:

user@t61:~/Time-Piece$ perl -I blib/arch/ -I blib/lib/  -MTime::Piece -le 'print gmtime(1000000000)->strftime("%s")'
1000000000
user@t61:~/Time-Piece$ 

And on a machine configured to UTC and using a German locale:

user@e643:~/Time-Piece$ perl -I blib/arch/ -I blib/lib/  -MTime::Piece -le 'print gmtime(1000000000)->strftime("%s")'                                                                                
1000000000
user@e643:~/Time-Piece$ date
Di 17. Jan 18:15:14 UTC 2017

user@e643:~/Time-Piece$

[smith153]

Should be fixed in 1.31_03
But can reopen if needed.