Refactor shard iteration out of dataset base

[kralka]

• Break the cyclical dependency between DatasetBase and ShardInfoIterator.
• Refactor *ShardInfoIterator into separate modules.
• Part of Allow arbitrary shard iteration #200

[gemini-code-assist]

Summary of Changes

Hello @kralka, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on a significant architectural improvement within the sedpack.io package. The core purpose is to enhance modularity and resolve a cyclical dependency by relocating the ShardInfoIterator and CachedShardInfoIterator classes from the DatasetBase module into a new, dedicated shard_info_iterator package. This change promotes cleaner separation of concerns, making the codebase more maintainable and easier to understand by decoupling the dataset iteration logic from the dataset base definition.

Highlights

• Dependency Management: This refactoring successfully breaks a cyclical dependency between DatasetBase and the shard information iterators, improving the architectural clarity and maintainability of the sedpack.io package.
• API Changes (Internal): The ShardInfoIterator and CachedShardInfoIterator constructors now directly accept dataset_path and dataset_info instead of a DatasetBase instance, making them more independent.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point in your pull request via creating an issue comment (i.e. comment on the pull request page) using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in issue comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments or fill out our survey to provide feedback.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request successfully refactors the ShardInfoIterator and CachedShardInfoIterator classes out of dataset_base.py into a new shard_info_iterator module. This is a great improvement as it breaks a cyclical dependency and improves the overall code structure. The changes are well-implemented across the affected files. I have a couple of suggestions for the newly created cached_shard_info_iterator.py file to further improve modularity and documentation clarity.