c type-alias getter thing

build.py

@@ -0,0 +1,11 @@
+from __future__ import annotations
+
+from setuptools import Extension, setup
+
+setup(
+    ext_modules=[
+        Extension(
+            name="basedtyping.type_alias_value_getter", sources=["c/type_alias_value_getter.c"]
+        )
+    ]
+)

c/type_alias_value_getter.c

@@ -0,0 +1,45 @@
+#define PY_SSIZE_T_CLEAN
+#include <Python.h>
+
+typedef struct {
+    PyObject_HEAD
+    PyObject *name;
+    PyObject *type_params;
+    PyObject *compute_value;
+    PyObject *value;
+    PyObject *module;
+} typealiasobject;
+
+static PyObject *
+foo_test(PyObject *self, PyObject *args)
+{
+    PyObject *alias;
+    if (!PyArg_ParseTuple(args, "O", &alias))
+        return NULL;
+    typealiasobject *ta = (typealiasobject *)alias;
+    return Py_NewRef(ta->compute_value);
+}
+
+static PyMethodDef foo_methods[] = {
+    /* The cast of the function is necessary since PyCFunction values
+     * only take two PyObject* parameters, and keywdarg_parrot() takes
+     * three.
+     */
+    {"test", (PyCFunction)(void(*)(void))foo_test, METH_VARARGS,
+     "debug alias."},
+    {NULL, NULL, 0, NULL}   /* sentinel */
+};
+
+static struct PyModuleDef foo = {
+    PyModuleDef_HEAD_INIT,
+    "foo",
+    NULL,
+    -1,
+    foo_methods
+};
+
+PyMODINIT_FUNC
+PyInit_foo(void)
+{
+    PyModule_Create(&foo);
+};

pyproject.toml

@@ -6,6 +6,7 @@ authors = [
 description = "Utilities for basedmypy"
 name = "basedtyping"
 version = "0.1.4"
+build = "build.py"
 
 [tool.poetry.dependencies]
 python = "^3.8"