How to make global imports from a function?

Question

I fear that this is a messy way to approach the problem but...

let's say that I want to make some imports in Python based on some conditions.

For this reason I want to write a function:

def conditional_import_modules(test):
    if test == 'foo':
        import onemodule, anothermodule
    elif test == 'bar':
        import thirdmodule, and_another_module
    else:
        import all_the_other_modules

Now how can I have the imported modules globally available?

For example:

conditional_import_modules(test='bar')
thirdmodule.myfunction()

Answer 1

Imported modules are just variables - names bound to some values. So all you need is to import them and make them global with global keyword.

Example:

>>> math
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'math' is not defined
>>> def f():
...     global math
...     import math
...
>>> f()
>>> math
<module 'math' from '/usr/local/lib/python2.6/lib-dynload/math.so'>

Answer 2

You can make the imports global within a function like this:

def my_imports(module_name):
    globals()[module_name] = __import__(module_name)

Answer 3

I've just had the similar problem, here is my solution:

class GlobalImport:

    def __enter__(self):
        return self

    def __call__(self):
        import inspect
        self.collector = inspect.getargvalues(inspect.getouterframes(inspect.currentframe())[1].frame).locals

    def __exit__(self, *args):
        globals().update(self.collector)

then, anywhere in the code:

with GlobalImport() as gi:
    import os, signal, atexit, threading, _thread
    # whatever you want it won't remain local
    # if only 
    gi()
    # is called before the end of this block

# there you go: use os, signal, ... from whatever place of the module