On Sep 24, 8:37 am, David Cramer <[EMAIL PROTECTED]> wrote: > I was digging through some code today, and I noticed imports are > happening within a lot of functions. It was my knowledge that it works > like so: > > import in a function is the same as ruby's load or php's include -- > its executed everytime the function is > > import in a module outside a function is like ruby's require or php's > require_once -- its loaded and cached in memory
That's not the case. Try the following: # importme.py print "running importme" def three(): print "3 - from importme" # test1.py import importme importme.three() # test2.py def one(): import importme print "1" importme.three() def two(): import importme print "2" importme.three() one() two() $ python test1.py running importme 3 - from importme $ python test2.py running importme 1 3 - from importme 2 3 - from importme As you can see, the initial print statement in importme.py only executes once, even when "import importme" is run twice (from inside functions). As I understand it, Python's "import" statement checks sys.modules to see if something has been imported already. If it hasn't, the module is loaded for the first time and executed. If it has already been imported (and hence is in sys.modules) then no extra code is loaded or executed - the import statement merely ensures that a reference to that module is available in the function's scope. As a result the performance overhead from having imports inside functions as opposed to at module level should be virtually non- existent. I don't think we need to worry about this - and like Jeremy said, usually there's a reason for doing it (avoiding importing something unless it's actually going to be needed, or avoiding circular imports). Cheers, Simon --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django developers" group. To post to this group, send email to django-developers@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-developers?hl=en -~----------~----~----~----~------~----~------~--~---
