Make pyimport able to return module attributes (#4395)

Before this PR, `pyimport` can be used like: `pyimport("package")` or `pyimport("package.module")` but `pyimport("package.attribute")` fails. This updates `pyimport` to also work to get package attributes.

I also updated the docs for pyimport.

conftest.py

@@ -35,18 +35,18 @@ pytest_pyodide.runner.NODE_FLAGS.extend(["--experimental-wasm-stack-switching"])
 # We need to go through and touch them all once to keep everything okay.
 pytest_pyodide.runner.INITIALIZE_SCRIPT = """
     pyodide.globals.get;
+    pyodide.runPython("import pyodide_js._api; del pyodide_js");
+    pyodide._api.importlib.invalidate_caches;
+    pyodide._api.package_loader.unpack_buffer;
+    pyodide._api.package_loader.get_dynlibs;
     pyodide._api.pyodide_code.eval_code;
     pyodide._api.pyodide_code.eval_code_async;
     pyodide._api.pyodide_code.find_imports;
     pyodide._api.pyodide_ffi.register_js_module;
     pyodide._api.pyodide_ffi.unregister_js_module;
-    pyodide._api.importlib.invalidate_caches;
-    pyodide._api.package_loader.unpack_buffer;
-    pyodide._api.package_loader.get_dynlibs;
-    pyodide.runPython("");
     pyodide.pyimport("pyodide.ffi.wrappers").destroy();
     pyodide.pyimport("pyodide.http").destroy();
-    pyodide.pyimport("pyodide_js._api")
+    pyodide.pyimport("pyodide_js._api");
 """
 
 only_node = pytest.mark.xfail_browsers(

docs/project/changelog.md

@@ -21,11 +21,15 @@ myst:
 
 - {{ Breaking }} `pyodide-build` entrypoint is removed in favor of `pyodide`.
   This entrypoint was deprecated since 0.22.0.
+  {pr}`4368`
 
 - {{ Enhancement }} Added apis to discard extra arguments when calling Python
   functions.
   {pr}`4392`
 
+- {{ Enhancement }} Updated `pyimport` to support `pyimport("module.attribute")`.
+  {pr}`4395`
+
 ### Packages
 
 - Upgraded scikit-learn to 1.4.0 {pr}`4409`

src/js/api.ts

@@ -451,31 +451,26 @@ export class PyodideAPI {
   /**
    * Imports a module and returns it.
    *
-   * .. admonition:: Warning
+   * If `name` has no dot in it, then `pyimport(name)` is approximately
-   *    :class: warning
+   * equivalent to:
-   *
+   * ```js
-   *    This function has a completely different behavior than the old removed pyimport function!
+   * pyodide.runPython(`import ${name}; ${name}`)
-   *
+   * ```
-   *    ``pyimport`` is roughly equivalent to:
+   * except that `name` is not introduced into the Python global namespace. If
-   *
+   * the name has one or more dots in it, say it is of the form `path.name`
-   *    .. code-block:: js
+   * where `name` has no dots but path may have zero or more dots. Then it is
-   *
+   * approximately the same as:
-   *      pyodide.runPython(`import ${pkgname}; ${pkgname}`);
+   * ```js
-   *
+   * pyodide.runPython(`from ${path} import ${name}; ${name}`);
-   *    except that the global namespace will not change.
+   * ```
-   *
-   *    Example:
-   *
-   *    .. code-block:: js
-   *
-   *      let sysmodule = pyodide.pyimport("sys");
-   *      let recursionLimit = sysmodule.getrecursionlimit();
    *
    * @param mod_name The name of the module to import
-   * @returns A PyProxy for the imported module
+   *
+   * @example
+   * pyodide.pyimport("math.comb")(4, 2) // returns 4 choose 2 = 6
    */
-  static pyimport(mod_name: string): PyProxy {
+  static pyimport(mod_name: string): any {
-    return API.importlib.import_module(mod_name);
+    return API.pyodide_base.pyimport_impl(mod_name);
   }
 
   /**
@@ -749,6 +744,7 @@ API.finalizeBootstrap = function (): PyodideInterface {
   API.pyodide_code = import_module("pyodide.code");
   API.pyodide_ffi = import_module("pyodide.ffi");
   API.package_loader = import_module("pyodide._package_loader");
+  API.pyodide_base = import_module("_pyodide._base");
 
   API.sitepackages = API.package_loader.SITE_PACKAGES.__str__();
   API.dsodir = API.package_loader.DSO_DIR.__str__();

src/js/types.ts

@@ -309,6 +309,7 @@ export interface API {
   pyodide_py: any;
   pyodide_code: any;
   pyodide_ffi: any;
+  pyodide_base: any;
   globals: PyProxy;
   rawRun: (code: string) => [number, string];
   runPythonInternal: (code: string) => any;

src/py/_pyodide/_base.py

@@ -621,3 +621,11 @@ def find_imports(source: str) -> list[str]:
                 continue
             imports.add(module_name.split(".")[0])
     return list(sorted(imports))
+
+
+def pyimport_impl(path: str) -> Any:
+    [stem, *fromlist] = path.rsplit(".", 1)
+    res = __import__(stem, fromlist=fromlist)
+    if fromlist:
+        res = getattr(res, fromlist[0])
+    return res

src/tests/test_pyodide.py

@@ -41,7 +41,15 @@ def test_ffi_import_star():
     exec("from pyodide.ffi import *", {})
 
 
-def test_pyimport(selenium):
+def test_pyimport1():
+    from _pyodide._base import pyimport_impl
+
+    assert pyimport_impl("pyodide").__name__ == "pyodide"
+    assert pyimport_impl("pyodide.console").__name__ == "pyodide.console"
+    assert pyimport_impl("pyodide.console.BANNER").startswith("Python ")
+
+
+def test_pyimport2(selenium):
     selenium.run_js(
         """
         let platform = pyodide.pyimport("platform");
@@ -1155,7 +1163,7 @@ def test_js_stackframes(selenium):
         ["<exec>", "c1"],
         ["test.html", "b"],
         ["pyodide.asm.js", "pyimport"],
-        ["importlib/__init__.py", "import_module"],
+        ["_pyodide/_base.py", "pyimport_impl"],
     ]
     assert normalize_tb(res[: len(frames)]) == frames