How to Call a Function From a Dynamic Python Module Using Variables python function variables

Learn how to dynamically call functions stored as variables from imported Python modules using `import_module` and `getattr`, plus practical examples for better understanding.
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This video is based on the question https://stackoverflow.com/q/66878212/ asked by the user 'John Herwig' ( https://stackoverflow.com/u/13252454/ ) and on the answer https://stackoverflow.com/a/66878379/ provided by the user 'Karl Knechtel' ( https://stackoverflow.com/u/523612/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Call a Function From a Dynamic Python Module Using Variables

When working with Python, you might find yourself in a situation where you need to call a function that's stored as a variable in a Python file, and that file is also stored as a variable. This use case is common when utilizing dynamic imports, especially when managing multiple modules. Let’s break down how to achieve this effectively.

Understanding the Problem

Imagine you have multiple Python files, each containing similar functions. You want to dynamically import these files and call specific functions stored as variables. Here's a quick summary of the scenario:

You have several Python files (file1.py, file2.py), and each contains functions that you want to invoke.

You want to import these files programmatically and access the functions they contain without manually specifying each function.

The initial attempt might look something like this:

[[See Video to Reveal this Text or Code Snippet]]

The Solution

1. Importing the Module

First, note that using import_module will return a module object, similar to what a standard import does. The confusion arises when trying to use syntax like:

[[See Video to Reveal this Text or Code Snippet]]

This approach searches for a module named test_file, but that’s not how dynamic importing works with variable names.

2. Accessing Functions as Attributes

Instead of trying to import functions directly using the from ... import ... syntax, you can simply access them through the module object returned by import_module. Here’s how:

[[See Video to Reveal this Text or Code Snippet]]

3. Utilizing getattr

Using getattr, we access the function stored within the module object. This is effective because all attributes including functions are stored in the module object:

[[See Video to Reveal this Text or Code Snippet]]

This method doesn't differentiate between variable types; it works equally well with functions as with other data types.

4. Practical Example

Suppose your file1.py and file2.py contain the same function names but with different implementations, the above code allows you to call any desired function dynamically:

[[See Video to Reveal this Text or Code Snippet]]

By invoking func(), you can seamlessly call that function regardless of which file/module it originated from.

Conclusion

To summarize:

Use import_module to dynamically import your Python scripts.

Access functions using getattr on the module object.

Call the functions directly once accessed.

With this approach, you can manage and utilize multiple Python modules effectively without hard-coding function calls.