How to selectively import module in python?

Question

I have several different modules, and I need to import one of them depending on different situations, for example:

if check_situation() == 1:
    import helper_1 as helper
elif check_situation() == 2:
    import helper_2 as helper
elif ...
    ...
else:
    import helper_0 as helper

these helpers contain same dictionaries dict01, dict02, dict03...but have different values to be called in different situations.

But this has some problems:

1. import sentences are all written in the top of a file, but check_situation() function here needs prerequisites so that it's now far from top.
2. more than 1 file needs this helper module, so it's hard and ugly to use this kind of import.

So, how to re-arrange these helpers?

Answer 1

Firstly, there is no strict requirement that import statements need to be at the top of a file, it is more a style guide thing.

Now, importlib and a dict can be used to replace your if/elif chain:

import importlib

d = {1: 'helper_1', 2: 'helper_2'}
helper = importlib.import_module(d.get(check_situation(), 'helper_0'))

But it's just syntactic sugar really, I suspect you have bigger fish to fry. It sounds like you need to reconsider your data structures, and redesign code.

Anytime you have variables named like dict01, dict02, dict03 it is a sure sign that you need to gear up a level, and have some container of dicts e.g. a list of them. Same goes for your 'helper' module names ending with digits.