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[Python-Dev] requirements for moving __import__ over toimportlib?
PJ Ebypje at telecommunity.com
Wed Feb 8 03:35:48 CET 2012
On Tue, Feb 7, 2012 at 6:40 PM, Terry Reedy <tjreedy at udel.edu> wrote:> importlib could provide a parameterized decorator for functions that are> the only consumers of an import. It could operate much like this:>> def imps(mod):> def makewrap(f):> def wrapped(*args, **kwds):> print('first/only call to wrapper')> g = globals()> g[mod] = __import__(mod)> g[f.__name__] = f> f(*args, **kwds)> wrapped.__name__ = f.__name__> return wrapped> return makewrap>> @imps('itertools')> def ic():> print(itertools.count)>> ic()> ic()> #> first/only call to wrapper> <class 'itertools.count'>> <class 'itertools.count'>>If I were going to rewrite code, I'd just use lazy imports (seehttp://pypi.python.org/pypi/Importing ). They're even faster than thisapproach (or using plain import statements), as they have zero per-callfunction call overhead. It's just that not everything I write can dependon Importing.Throw an equivalent into the stdlib, though, and I guess I wouldn't have toworry about dependencies...(To be clearer; I'm talking about thehttp://peak.telecommunity.com/DevCenter/Importing#lazy-imports feature,which sticks a dummy module subclass instance into sys.modules, whose__gettattribute__ does a reload() of the module, forcing the normal importprocess to run, after first changing the dummy object's type to somethingthat doesn't have the __getattribute__ any more. This ensures that allaccesses after the first one are at normal module attribute access speed. That, and the "whenImported" decorator from Importing would probably be ofgeneral stdlib usefulness too.)-------------- next part --------------An HTML attachment was scrubbed...URL: <http://mail.python.org/pipermail/python-dev/attachments/20120207/ac9c49fd/attachment.html>
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