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Comment by smitherfield | Hacker News Reader

Sure, but, just spitballing here, could a substantial fraction of imported code benefit even with a very conservative heuristic?

In any case, given your points, it seems like a future Python version ought to introduce a new version of the import statement with lazy semantics (which, besides eliminating dead code, is also IMO the more correct/explicit behavior when importing symbols).

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It'd be pretty easy to do the experiment, since you can override the import logic and do lazy imports, eg.

    class LazyModule:
        def __init__(self, name):
            self.name = name
        def __getattr__(self, key):
            mod = {}
            exec('import %s as mod', mod)
            self.mod = mod['mod']
            return getattr(self.mod, key)

    class LazyImporter:
        def get_module(self, name):
            return LazyModule(name)

That's kind of what I was hoping. I suspect a vast proportion of normal Python code doesn't use the meta programming and run on import and so on.

If a module imports anything, it cannot be assumed clean, since any of its imports may execute code, and they will not be available at compile time.

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