dynamic import - Dynamically importing Python module

31
votes

I have a trusted remote server that stores many custom Python modules. I can fetch them via HTTP (e.g. using urllib2.urlopen) as text/plain, but I cannot save the fetched module code to the local hard disk. How can I import the code as a fully operable Python module, including its global variables and imports?
I suppose I have to use some combination of exec and imp module's functions, but I've been unable to make it work yet.

3
pythondynamic-import
are you downloading them over ssl or is every intermediate router trusted as well? :P - aaronasterling
Actually, yes - both the module storage and the front-end server are parts of a single system (and are even located in the same server room). For now, suppose there are no security implications: even if I download the code over SSL, the question of how to interpret it still stands. - dpq

3 Answers

47
votes

It looks like this should do the trick: importing a dynamically generated module

>>> import imp
>>> foo = imp.new_module("foo")
>>> foo_code = """
... class Foo:
...     pass
... """
>>> exec foo_code in foo.__dict__
>>> foo.Foo.__module__
'foo'
>>>

Also, as suggested in the ActiveState article, you might want to add your new module to sys.modules:

>>> import sys
>>> sys.modules["foo"] = foo
>>> from foo import Foo
<class 'Foo' …>
>>>
5
votes

Here's something I bookmarked a while back that covers something similar:

It's a bit beyond what you want, but the basic idea is there.

0
votes

Python3 version
(attempted to edit other answer but the edit que is full)

import imp

my_dynamic_module = imp.new_module("my_dynamic_module")
exec("""
class Foo:
    pass
""", my_dynamic_module.__dict__)

Foo = my_dynamic_module.Foo
foo_object = Foo()

# register it on sys
import sys
sys.modules[my_dynamic_module.__name__] = my_dynamic_module