Running code on import from dynamically generated module

Question

I have used this SO answer to dynamically generate a module x and register it in sys.modules. I want a piece of code to run automatically when an import is called on this module. so for example I want print "you just imported module x". So it behaves like:

>>> import x
you just imported module x

How do I get this behavior?

why not put it in the module itself? i.e right before `class Foo:` in the example — Padraic Cunningham, Dec 04 '15 at 19:08
Should this happen every time the module is imported? If so, you'll probably need to mess with import hooks to do that. — user2357112, Dec 04 '15 at 19:15
Padraic that doesn't give the desired behavior because the print code is executed when `exec` is called not when the module is imported. — Hamzeh Alsalhi, Dec 04 '15 at 19:37

score 0 · Answer 1 · answered Dec 04 '15 at 19:09

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To simply extend the example given in the selected answer you could something like this.

print "You just imported module {}".format(foo.Foo.__module__)

answered Dec 04 '15 at 19:09

Jared Mackey

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If you do that and then run the line from the example `exec foo_code in foo.__dict__` the print will happen as soon as you call `exec` this does not make it so the print runs on `import foo` – Hamzeh Alsalhi Dec 04 '15 at 19:36
That would be true if that was in the module being imported. My understand is this code would go in the module doing the importing. – Jared Mackey Dec 04 '15 at 19:37

score 0 · Answer 2 · answered Dec 04 '15 at 19:10

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Any "orphan" code (code that isn't written inside a class or a function, or inside an if __name__ == '__main__:' block) will be executed when you import the module.

answered Dec 04 '15 at 19:10

DeepSpace

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Running code on import from dynamically generated module

2 Answers2