Add stubs

.gitignore

@@ -1,81 +1,20 @@
-/target
+# IDEs
+/.idea/
+/.vscode/
 
-# Byte-compiled / optimized / DLL files
+# Caches
+.DS_Store
 __pycache__/
-.pytest_cache/
-*.py[cod]
+/.*cache/
+/.hypothesis/
 
-# C extensions
+# Build
 *.so
-
-.hypothesis/
-
-# docs generated rst
-docs/generated
-
-# Distribution / packaging
-.Python
-.venv/
-env/
-bin/
-build/
-develop-eggs/
-dist/
-eggs/
-lib/
-lib64/
-parts/
-sdist/
-var/
-include/
-man/
-venv/
-*.egg-info/
-.installed.cfg
-*.egg
-
-# Installer logs
-pip-log.txt
-pip-delete-this-directory.txt
-pip-selfcheck.json
-
-# Unit test / coverage reports
-htmlcov/
-.tox/
-.coverage
-.cache
-nosetests.xml
-coverage.xml
-
-# Translations
-*.mo
-
-# Mr Developer
-.mr.developer.cfg
-.project
-.pydevproject
-
-# Rope
-.ropeproject
-
-# Django stuff:
-*.log
-*.pot
-
-.DS_Store
-
-# Sphinx documentation
-docs/_build/
-
-# PyCharm
-.idea/
-
-# VSCode
-.vscode/
-
-# Pyenv
-.python-version
-
-# testing
-data/
-fixture/
+*.pyi
+/target/
+/dist/
+/docs/_build/
+
+# Coverage
+/.coverage
+/coverage.xml

Cargo.toml

@@ -5,8 +5,8 @@ edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 [lib]
-name = "zarrs"
-crate-type = ["cdylib"]
+name = "zarrs_python"
+crate-type = ["cdylib", "rlib"]
 
 [dependencies]
 pyo3 = "0.22.6"
@@ -18,6 +18,7 @@ openssl = { version = "0.10", features = ["vendored"] }
 numpy = "0.22.1"
 unsafe_cell_slice = "0.2.0"
 serde_json = "1.0.128"
+pyo3-stub-gen = { version = "0.6.1", git = "https://github.com/flying-sheep/pyo3-stub-gen.git", branch = "py-untyped-array" }
 
 [profile.release]
 lto = true

build.rs

@@ -0,0 +1,32 @@
+use std::env;
+use std::path::PathBuf;
+use std::process::Command;
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    maybe_generate_stubs()?;
+    Ok(())
+}
+
+/// Generate stubs if we’re compiling the library
+/// Returns `true` if stubs were generated
+fn maybe_generate_stubs() -> Result<bool, Box<dyn std::error::Error>> {
+    if env::var("CARGO_BIN_NAME") != Err(env::VarError::NotPresent) {
+        return Ok(false);
+    }
+
+    // Find an existing `stub_gen` binary or exit silently
+    let Some(bin_path) = ["debug", "release"]
+        .into_iter()
+        .filter_map(|mode| {
+            let p = PathBuf::from(format!("target/{mode}/stub_gen"));
+            p.exists().then_some(p)
+        })
+        .next()
+    else {
+        return Ok(false);
+    };
+
+    // If we’re compiling the library, generate stubs first
+    Command::new(bin_path).spawn()?.wait()?;
+    Ok(true)
+}

docs/contributing.md

@@ -29,3 +29,13 @@ pytest -n auto
 ```
 
 for parallelized tests.  Most tests have been copied from the `zarr-python` repository with the exception of `test_pipeline.py` which we have written.
+
+## Type hints
+
+When authoring Python code, your IDE will not be able to analyze the extension module `zarrs._internal`.
+But thanks to [`pyo3-stub-gen`][], we can generate type stubs for it!
+
+To build the stub generator, run `cargo build --bin stub_gen`.
+Afterwards, whenever you `cargo build`, `maturin build` or interact with your editor’s rust language server (e.g. `rust-analyzer`), the type hints will be updated.
+
+[`pyo3-stub-gen`]: https://github.com/Jij-Inc/pyo3-stub-gen

pyproject.toml

@@ -9,6 +9,7 @@ classifiers = [
     "Programming Language :: Rust",
     "Programming Language :: Python :: Implementation :: CPython",
     "Programming Language :: Python :: Implementation :: PyPy",
+    "Typing :: Typed",
 ]
 dynamic = ["version"]
 dependencies = [
@@ -41,9 +42,9 @@ test = [
     "requests",
     "mypy",
     "hypothesis",
-    "pytest-xdist"
+    "pytest-xdist",
 ]
-dev = ["maturin"]
+dev = ["maturin", "pip"]
 doc = ["sphinx>=7.4.6", "myst-parser"]
 
 [tool.maturin]

src/bin/stub_gen.rs

@@ -0,0 +1,7 @@
+use pyo3_stub_gen::Result;
+
+fn main() -> Result<()> {
+    let stub = zarrs_python::stub_info()?;
+    stub.generate()?;
+    Ok(())
+}

src/lib.rs

@@ -6,6 +6,8 @@ use numpy::npyffi::PyArrayObject;
 use numpy::{IntoPyArray, PyArray1, PyUntypedArray, PyUntypedArrayMethods};
 use pyo3::exceptions::{PyRuntimeError, PyTypeError, PyValueError};
 use pyo3::prelude::*;
+use pyo3_stub_gen::define_stub_info_gatherer;
+use pyo3_stub_gen::derive::{gen_stub_pyclass, gen_stub_pymethods};
 use rayon::iter::{IntoParallelIterator, ParallelIterator};
 use rayon_iter_concurrent_limit::iter_concurrent_limit;
 use std::borrow::Cow;
@@ -37,6 +39,7 @@ trait CodecPipelineStore: Send + Sync {
 }
 
 // TODO: Use a OnceLock for store with get_or_try_init when stabilised?
+#[gen_stub_pyclass]
 #[pyclass]
 pub struct CodecPipelineImpl {
     pub(crate) codec_chain: Arc<CodecChain>,
@@ -234,6 +237,7 @@ impl CodecPipelineImpl {
     }
 }
 
+#[gen_stub_pymethods]
 #[pymethods]
 impl CodecPipelineImpl {
     #[pyo3(signature = (
@@ -531,3 +535,5 @@ fn _internal(m: &Bound<'_, PyModule>) -> PyResult<()> {
     m.add_class::<CodecPipelineImpl>()?;
     Ok(())
 }
+
+define_stub_info_gatherer!(stub_info);