Merge pull request #103 from lucascolley/contributor-docs

docs/contributing.md

@@ -6,11 +6,14 @@ converting code to consume the standard.
 
 Thanks to [all contributors](contributors.md) so far!
 
-## How to contribute a function
+## How to contribute a new function
 
 - [Open an issue](https://github.com/data-apis/array-api-extra/issues/new) to
-  propose the new function.
-- Add the implementation of your function to `src/array_api_extra/_funcs.py`.
+  propose the new function. You may want to wait for initial feedback on the
+  issue before diving into an implementation. Feel free to skip this step if
+  there is already an open issue for the function.
+- Add the implementation of your function to
+  `src/array_api_extra/_lib/_funcs.py`.
   - Ensure that your function includes type annotations and a
     [numpydoc-style docstring](https://numpydoc.readthedocs.io/en/latest/format.html).
   - Add your function to `__all__` at the top of the file.
@@ -20,6 +23,33 @@ Thanks to [all contributors](contributors.md) so far!
 - Add your function to `docs/api-reference.md`.
 - [Make a PR!](https://github.com/data-apis/array-api-extra/pulls)
 
+## How to add delegation to a function
+
+See [the tracker for adding delegation][delegation-tracker].
+
+[delegation-tracker]: https://github.com/data-apis/array-api-extra/issues/100
+
+- If you would like to discuss the task before diving into the implementation,
+  click on the three dots next to the function on the tracker issue, and choose
+  "Convert to sub-issue".
+- Create a function in `src/array_api_extra/_delegation.py` with a signature
+  matching the function in `src/array_api_extra/_lib/_funcs.py`, and move the
+  docstring to the new function. Leave a one-line docstring in `_funcs.py`,
+  pointing to `_delegation.py` to see the full docstring.
+- Also move the initial `array_namespace` call and any input validation over to
+  the new function.
+- Add delegation to backends using the `if _delegate` pattern. See
+  `src/array_api_extra/_lib/_backends.py` for the full list of backends we have
+  worked with so far.
+- After all delegation layers, return the result from the implementation in
+  `_funcs`.
+- Simplify the signature in `_funcs.py` to remove impossible arguments now that
+  it is only called internally via `_delegation`. For example, the `xp`
+  parameter can be changed from type `ModuleType | None` to `ModuleType`.
+- Don't worry if you are not sure how to do some of the above steps or think you
+  might have done something wrong -
+  [make a PR!](https://github.com/data-apis/array-api-extra/pulls)
+
 ## Development workflow
 
 If you are an experienced contributor to Python packages, feel free to develop