CODEWITHSUNDEEP
pythonimportmodule
peterk
peterk

Reputation: 16

Using Python modules based on a condition

I want to import modules dynamically in my class depending on some conditions. 

    class Test(object):
        def __init__ (self,condition):
            if condition:
                import module1 as mymodule
            else:
                import module2 as mymodule

            self.mymodule = mymodule

        def doTest(self):
            self.mymodule.doMyTest

where module1 and module2 implement doMyTest in different way.

Calling it as

    mytest1 = Test(true)  # Use module1
    mytest2.doTest()

    mytest2 = Test(false)  # Use module2
    mytest2.doTest()

This works but is there possibly a more idiomatic way? Are there any possible problems?

Upvotes: 0

Views: 106

Answers (1)

abarnert
abarnert

Reputation: 365717

Of course normally you don't want to import modules in the middle of an __init__ method, but a testing class is an obvious exception to that rule, so let's ignore that part and imagine you were doing this at top level:

if test_c_implementation:
    import c_mymodule as mymodule
else:
    import py_mymodule as mymodule

That's perfectly idiomatic. In fact, you see code like that in the stdlib and other code written by core developers.

Except in the very-common EAFP cases, where the condition is just there to avoid an exception, in which case it's more idiomatic to just do this:

try:
    import lxml.etree as ET
except ImportError:
    import xml.etree.cElementTree as ET

Upvotes: 1

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