Thanks to Tom / Matias / Brian for taking the time to reply, and for providing some good links, this was *exactly* what I needed.
In regards to circular import issues, this is pretty much the main reason I've put imports inside function/method before, and I agree that most of the time it can be resolved with re-organization. Pretty shameful that after almost 6 years of (fairly advanced) Python coding, I still finding myself not knowing some of the basic 101 stuff.. Slightly off topic but, does anyone else have that issue when coding? (i.e. doing really complex code, but forgetting/not knowing some of the real basic stuff). On Thu, Jun 2, 2011 at 3:56 PM, Brian Bouterse <bmbou...@gmail.com> wrote: > Yes relative imports are explicitly discouraged in PEP > 8<http://www.python.org/dev/peps/pep-0008/>. > Look for the imports section. > > I do not recommend importing at runtime which is what you are doing when > you put imports inside function/methods. There are performance problems > when calling imports repeatedly. One possible method is to use a lazy > import paradigm described at the end of this section on import > overhead<http://wiki.python.org/moin/PythonSpeed/PerformanceTips#Import_Statement_Overhead> > . > > The only reason I think it is ok to do imports inside function/method code > is if you don't know what you need to import until runtime, but in those > cases you wouldn't use the standard "import foo" syntax, since you would > need to dynamically choose what to import. > > Another reason folks hide imports inside function/method code is to solve > circular import issues. This is a consistently unproductive solution and > will create problems over time through hidden import dependencies that > aren't discovered until runtime. circular imports can almost always be > resolved through some code and package reorganization. I like this > article <http://effbot.org/zone/import-confusion.htm> on how import works > in python. > > Brian > > > > On Thu, Jun 2, 2011 at 10:39 AM, Cal Leeming [Simplicity Media Ltd] < > cal.leem...@simplicitymedialtd.co.uk> wrote: > >> Hey guys, >> >> This is more of a python question, than a Django specific one, but it's >> been bugging me for years now lol. >> >> I'm trying to figure out if it is better to do imports at the top of the >> file, or within the function/methods themselves. >> >> I guess the questions I'm asking are: >> >> - Is there any (serious) performance issues by doing imports every >> time the function/method is called >> - Is there a preferred style / guideline when it comes to imports? >> (maybe a PEP somewhere?) >> - Are relative imports discouraged? (from .. import package) >> >> Obviously, the answers would depend on different scenarios, so I'm looking >> for a discussion really, rather than a set in stone answer. >> >> Example 1: >> import os >> def test(): >> print os.uname() >> def test2(): >> print os.uname() >> test() >> test2() >> >> Example 2: >> import os >> class test: >> def test(self): >> print os.uname() >> >> >> Example 2: >> class test: >> def test(self): >> import os >> print os.uname() >> def test2(self): >> import os >> print os.uname() >> >> t = test() >> t.test() >> t.test2() >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Django users" group. >> To post to this group, send email to django-users@googlegroups.com. >> To unsubscribe from this group, send email to >> django-users+unsubscr...@googlegroups.com. >> For more options, visit this group at >> http://groups.google.com/group/django-users?hl=en. >> > > > > -- > Brian Bouterse > ITng Services > > -- > You received this message because you are subscribed to the Google Groups > "Django users" group. > To post to this group, send email to django-users@googlegroups.com. > To unsubscribe from this group, send email to > django-users+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/django-users?hl=en. > -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
