WIP: src layout for python

Readme.md

@@ -83,11 +83,25 @@ To create a mixed rust/python project, create a folder with your module name (i.
 my-project
 ├── Cargo.toml
 ├── my_project
-│   ├── __init__.py
-│   └── bar.py
+│   ├── __init__.py
+│   └── bar.py
 ├── Readme.md
 └── src
-    └── lib.rs
+    └── lib.rs
+```
+
+Alternatively, you can also put the python sources in a folder called `python_src`, which resembles the [src layout](https://hynek.me/articles/testing-packaging/#src) without conflicting with rust's `src` directory:
+
+```
+my-project
+├── Cargo.toml
+├── python_src
+│   └── my_project
+│       ├── __init__.py
+│       └── bar.py
+├── Readme.md
+└── src
+    └── lib.rs
 ```
 
 maturin will add the native extension as a module in your python folder. When using develop, maturin will copy the native library and for cffi also the glue code to your python folder. You should add those files to your gitignore.

src/build_context.rs

@@ -65,15 +65,30 @@ pub enum ProjectLayout {
 impl ProjectLayout {
     /// Checks whether a python module exists besides Cargo.toml with the right name
     pub fn determine(project_root: impl AsRef<Path>, module_name: &str) -> Result<ProjectLayout> {
-        let python_package_dir = project_root.as_ref().join(module_name);
-        if python_package_dir.is_dir() {
-            if !python_package_dir.join("__init__.py").is_file() {
-                bail!("Found a directory with the module name ({}) next to Cargo.toml, which indicates a mixed python/rust project, but the directory didn't contain an __init__.py file.", module_name)
+        let python_dir_root = project_root.as_ref().join(module_name);
+        let python_dir_python = project_root.as_ref().join("python_src").join(module_name);
+        let python_dir;
+        if python_dir_root.is_dir() {
+            python_dir = Some(python_dir_root);
+        } else if python_dir_python.is_dir() {
+            python_dir = Some(python_dir_python);
+        } else {
+            python_dir = None;
+        }
+
+        if let Some(python_dir) = python_dir {
+            if !python_dir.join("__init__.py").is_file() {
+                bail!(
+                    "Found a directory with the module name ({}) next to Cargo.toml, \
+                    which indicates a mixed python/rust project, \
+                    but the directory didn't contain an __init__.py file.",
+                    module_name
+                )
             }
 
             println!("🍹 Building a mixed python/rust project");
 
-            Ok(ProjectLayout::Mixed(python_package_dir))
+            Ok(ProjectLayout::Mixed(python_dir))
         } else {
             Ok(ProjectLayout::PureRust)
         }

test-crates/pyo3-mixed/pyo3_mixed/__init__.py

@@ -1,4 +1,4 @@
-from .python_module.double import double
+from .my_submodule.double import double
 from .pyo3_mixed import get_21
 
 

test-crates/pyo3-src-layout/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+authors = ["konstin <[email protected]>"]
+name = "pyo3-src-layout"
+version = "2.1.3"
+description = "Implements a dummy function combining rust and python using the python_src layout"
+readme = "Readme.md"
+edition = "2018"
+
+[package.metadata.maturin.scripts]
+get_42 = "pyo3_mixed:get_42"
+
+[package.metadata.maturin]
+classifier = [
+    "Programming Language :: Python",
+    "Programming Language :: Rust"
+]
+
+[dependencies]
+pyo3 = { version = "0.13.2", features = ["extension-module"] }
+
+[lib]
+name = "pyo3_src_layout"
+crate-type = ["cdylib"]