Thanks Terry! There indeed seems to be something wrong with my installation of pytz. I had a look around the zoneinfo dir, which is where build_tzinfo polls its info from, and a whole bunch of files are 0 bytes. Whenever I try to instantiate a timezone whose corresponding file is 0 bytes I get that error (it's trying to read the head of the tzinfo file to make sure the right magic bytes are in there, and reading 44 bytes out of a 0 byte file isn't going to work).
So I guess I'll poke around to find some specific help with pytz or a non-broken zoneinfo dir. On Wednesday, June 13, 2012 10:43:46 PM UTC+1, Terry Reedy wrote: > On 6/13/2012 4:55 PM, I wrote: > > Hi! > > > > I'm trying to get a handle on pytz (http://pytz.sourceforge.net/). I don't > > have root on the system I'll be running my script on, so I need to go for a > > local installation. I copied pytz into a folder in my sys.path and am > > importing from there. That part seems to work. I downloaded the tarball on > > http://pypi.python.org/pypi/pytz/#downloads > > > > So now I'm walking through the examples on > > http://pytz.sourceforge.net/#example-usage. This is what happens: > > > > Python 2.7.2 (default, Jun 12 2011, 15:08:59) [MSC v.1500 32 bit (Intel)] > > on win32 > > Type "help", "copyright", "credits" or "license" for more information. > > (InteractiveConsole) > >>>> from datetime import datetime, timedelta > >>>> from pytz import timezone > >>>> import pytz > >>>> utc = pytz.utc > >>>> utc.zone > > 'UTC' > >>>> eastern = timezone('US/Eastern') > > Traceback (most recent call last): > > File "<console>", line 1, in<module> > > File "C:\code\SoF\serversonfire\pytz\__init__.py", line 181, in timezone > > _tzinfo_cache[zone] = build_tzinfo(zone, fp) > > File "C:\code\SoF\serversonfire\pytz\tzfile.py", line 30, in build_tzinfo > > typecnt, charcnt) = unpack(head_fmt, fp.read(head_size)) > > error: unpack requires a string argument of length 44 > > > > > > Can anyone explain to me why that call fails? > > 1. Either pytz has a bug, it was not installed correctly, or it does not > work on windows. > > 2. If you read the module struct section of the fine manual, which you > can easily find by typing 'unpack' on the Index tab of the Windows help > version of the manual, it will tell you the following. Unpack takes two > arguments, a format defining character fields of specifics lengths and a > string whose length must be the sum of those lengths. (The contents of > each field must also match the format spec, but you never got that far.) > If there is a length mismatch, you get the message above. > > 3. In the specific case, we may presume that head_size is the sum of > field lengths for head_fmt. (You could check; if not, that is a bug.) > Since fp.read cannot read too many bytes, it must have read too little. > ("Read up to n bytes from the object and return them.") > > You could look in > C:\code\SoF\serversonfire\pytz\__init__.py > and see what file fp is supposed to be and then take a look at the file. > Is it empty? Is anything read before the statement that failer? > > -- > Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
