transformers copilot-instructions.md

copilot-instructions.md Guide for Hugging Face Transformers

This copilot-instructions.md file provides guidance for code agents working with this codebase.

Core Project Structure

• /src/transformers: This contains the core source code for the library
  • /models: Code for individual models. Models inherit from base classes in the root /src/transformers directory.
• /tests: This contains the core test classes for the library. These are usually inherited rather than directly run.
  • /models: Tests for individual models. Model tests inherit from common tests in the root /tests directory.
• /docs: This contains the documentation for the library, including guides, tutorials, and API references.

Coding Conventions for Hugging Face Transformers

• PRs should be as brief as possible. Bugfix PRs in particular can often be only one or two lines long, and do not need large comments, docstrings or new functions in this case. Aim to minimize the size of the diff.
• When writing tests, they should be added to an existing file. The only exception is for PRs to add a new model, when a new test directory should be created for that model.
• Code style is enforced in the CI. You can install the style tools with pip install -e .[quality]. You can then run make fixup to apply style and consistency fixes to your code.

Copying and inheritance

Many models in the codebase have similar code, but it is not shared by inheritance because we want each model file to be self-contained. We use two mechanisms to keep this code in sync:

• "Copied from" syntax. Functions or entire classes can have a comment at the top like this: # Copied from transformers.models.llama.modeling_llama.rotate_half or # Copied from transformers.models.t5.modeling_t5.T5LayerNorm with T5->MT5 These comments are actively checked by the style tools, and copies will automatically be updated when the base code is updated. If you need to update a copied function, you should either update the base function and use make fixup to propagate the change to all copies, or simply remove the # Copied from comment if that is inappropriate.
• "Modular" files. These files briefly define models by composing them using inheritance from other models. They are not meant to be used directly. Instead, the style tools automatically generate a complete modeling file, like modeling_bert.py, from the modular file like modular_bert.py. If a model has a modular file, the modeling file should never be edited directly! Instead, changes should be made in the modular file, and then you should run make fixup to update the modeling file automatically.