Dave Angel：
On Wed, Feb 8, 2012 at 10:05 AM, Dave Angel <d...@davea.name> wrote: > On 02/07/2012 08:48 PM, Lei Cheng wrote: > >> Hi all, >> >> In a py file, when to use import statements in the header, when to use >> import statements in the blocks where they are used? >> What are the best practices? >> Thanks! >> >> Pat >> >> Best practice is to put all the imports at the beginning of the module, > so they are easy to spot. > > If you put an import inside a function, it gets re-executed each time the > function is called, which is a waste of time. Not too much, since import > first checks sys.modules to see if it's already loaded. > > Also, avoid the from xxx import * form, as it pollutes the > namespace. And it makes it hard to figure out where a particular name is > declared. > > I believe these and other best practices can be found in pep8. > > http://www.python.org/dev/**peps/pep-0008/<http://www.python.org/dev/peps/pep-0008/> > > -- > > DaveA > > yeah, I read pep8. However I find in the file path/to/djcelery/loaders.py from django-celery source, there are so many import/from statements used inside functions, I do not know why the author coded like this. Are there any special facts?
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