clean: top-level __init__.py

[metaist]

I only want the most-used classes and functions at the top-most level. Everything else can be accessed more directly, if needed, but I don't want to pollute the namespace.

[metaist]

Me: I'm working on a python library that covers a few different kinds of functions and I have arranged them in several submodules. What are the pros and cons of importing every function in every submodule into init.py at the top-most level? What is the best practice? Please provide references where possible.

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ChatGPT: Importing all functions in every submodule into __init__.py is a way to provide a more convenient interface for your library users, but it can also have some drawbacks. Below are the pros and cons, along with some best practices:

Pros

1. Simplification: It simplifies the import statements for the users of your library. They can import functions directly from the library without needing to know about the internal package structure. (Reference: PEP 8 - Imports)

2. Encapsulation: By importing everything into the __init__.py, you have control over what parts of your package are exposed to the outside world. This encapsulation can improve the maintainability of your library, as changes to the internal structure won't necessarily impact the way users interact with it.

Cons

1. Namespace Pollution: If you import everything into __init__.py, all the functions are available in the main namespace. This can lead to collisions if there are functions with the same name in different submodules.

2. Performance: If the library is large, it can increase the startup time for your users, since importing the top-level package will import everything, even if not all of it is needed. (Reference: Importing Python Modules)

3. Understandability: It could make your code harder to understand, as it's less clear where a function is coming from. The import hierarchy of Python can help organize code and make it easier to understand, and collapsing all of this can lose some of these benefits.

Best Practices

Deciding whether to import everything in __init__.py depends on the specific use case, but here are some general best practices:

1. Selective Imports: Only import the most commonly used functions or classes into __init__.py. This way, you can provide a simple interface to your library without polluting the namespace too much.

2. Clear Documentation: Make sure you clearly document your library's structure and how to use it. If you do choose to import everything into __init__.py, make sure users know about this.

3. Avoid Star Imports: Do not use star imports (from module import *) in __init__.py. This can lead to unexpected name collisions and make it harder to understand which names are part of a module's public interface. (Reference: PEP 8 - Wildcard Imports)

4. __all__ Variable: Use the __all__ variable in your modules if you decide to use wildcard imports, so that you can control what names are exported when a client imports your module using from module import *.

Remember that these are guidelines, not strict rules, and the best choice depends on the specific use case, library size, and complexity.

[metaist]

Just re-read PEP 8 for the first time in a long time and while there's much I agree with, I'm surprised how much I disagree with. I should probably write a post about it.