So it isn't inefficient to import a bunch of modules that may not be used, say if only one function is used that doesn't rely on a larger module like numpy or pylab?
Thanks. Diez B. Roggisch-2 wrote: > > John [H2O] schrieb: >> Hello, Im writing some modules and I am a little confused about where to >> place my imports... >> >> I don't really do any class programming yet, just defining a bunch of >> functions, so presently I have something along the lines of: >> >> import sys >> import os >> import traceback >> >> >> def Foo1(a,b): >> import numpy >> import datetime >> return c >> >> def Foo2(a,b): >> import datetime >> >> c = Foo1(a,b) >> return c >> >> etc... >> >> Above obviously just for the form, but the point is, in some cases I may >> import modules twice, but other times I may not use them at all, so >> should I >> import everything into the main module? Or individually import them into >> functions. Is there a performance penalty either way? > > Usually, you should import on the top of the module. That's the cleanest > way, and the most performant one. > > There is a small performance penalty when doing it inside functions - > but not too much. It boils down to a lookup if the imported module has > already been imported before. > > > The only valid reason for doing imports inside functions is if you > otherwise get into circular dependency hell, or have modules that need > some manipulation of the sys.path before they actually can be imported. > This is never true for system modules, and certainly to avoid if possible. > > Diez > -- > http://mail.python.org/mailman/listinfo/python-list > > -- View this message in context: http://www.nabble.com/Where-to-place-imports-tp21627895p21628590.html Sent from the Python - python-list mailing list archive at Nabble.com. -- http://mail.python.org/mailman/listinfo/python-list
