Скачать или смотреть Reusable Methods in Python Classes: Sharing Implementations with LoadableChild

Learn how to implement shared methods in child classes of a parent class in Python while maintaining uniqueness in method implementation.
---
This video is based on the question https://stackoverflow.com/q/64067242/ asked by the user 'Alberto A' ( https://stackoverflow.com/u/1358829/ ) and on the answer https://stackoverflow.com/a/64067515/ provided by the user 'Slam' ( https://stackoverflow.com/u/2161778/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: In python, how to have two classes share implementation of a method that calls another method with specific implementations for each class

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Reusable Methods in Python Classes: Sharing Implementations with LoadableChild

In Python's object-oriented programming, it's common to encounter situations where multiple subclasses of a parent class require identical implementations of certain methods. However, in many cases, these methods may call other class-specific methods. This raises a significant question: How can you effectively share method implementations across classes while ensuring that specific functionalities remain unique to each class?

Let’s explore a practical example and lay out some structured solutions to tackle this challenge.

The Problem

Suppose you have a parent class named Parent with an abstract method load, which is implemented uniquely in its child classes childA and childB. Both subclasses share identical functionality in their load() method, but the call to another method, get_paths, is specific to each child.

Here's a simplified view of this problem:

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

The goal is to refactor this setup so that childA and childB can reuse the load() implementation without compromising their unique get_paths() methods.

Solution Breakdown

Approach 1: Creating a LoadableChild Mixin

One effective approach to solve this problem is by creating a mixin class that contains the shared load() implementation. Here’s how to do it:

Step 1: Define a LoadableChild class that inherits from Parent.

Step 2: Implement the load() method in the LoadableChild class.

Step 3: Have both child classes inherit from the LoadableChild class to inherit the shared load() functionality while maintaining their specific get_paths() methods.

Here’s the code demonstrating this approach:

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

Approach 2: Using a Separate LoadBase Class

Another method is to define a separate LoadBase class that handles the common functionality and then use it alongside Parent in each child class. This method emphasizes the order of inheritance, as it can affect method resolution order (MRO).

Here’s how this can be structured:

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

Important Considerations

When implementing these approaches, keep the following in mind:

MRO Considerations: The order of inheritance matters. If the mixin inherits from Parent, it may complicate the method resolution order.

Maintainability: Choose the method that not only fulfills your current requirements but also makes your code easier to maintain in the long run. Personally, many developers find the LoadableChild approach cleaner and more intuitive.

Conclusion

By adopting either the LoadableChild mixin or the LoadBase approach, you can effectively share method implementations across child classes while ensuring that their unique functionalities remain intact. This allows you to adhere to the DRY (Don't Repeat Yourself) principle in object-oriented programming, enhancing both code clarity and maintainability.

Feel free to experiment with these methods in your own projects and see which approach suits your needs best!