From bb829344b5cd95e95550c3af2ee9af4055c5c2bd Mon Sep 17 00:00:00 2001
From: Michael Carlstrom <rmc@carlstrom.com>
Date: Fri, 26 Jul 2024 10:03:06 -0400
Subject: [PATCH] prototype

---
 include/pybind11/pytypes.h |  9 +++++++++
 include/pybind11/typing.h  | 37 ++++++++++++++++++++++++++++++++++++-
 tests/test_pytypes.cpp     | 17 +++++++++++++++++
 tests/test_pytypes.py      | 28 ++++++++++++++++++++++++++++
 4 files changed, 90 insertions(+), 1 deletion(-)

diff --git a/include/pybind11/pytypes.h b/include/pybind11/pytypes.h
index f26c307a8..c846f48a6 100644
--- a/include/pybind11/pytypes.h
+++ b/include/pybind11/pytypes.h
@@ -182,6 +182,10 @@ public:
     /// Get or set the object's docstring, i.e. ``obj.__doc__``.
     str_attr_accessor doc() const;
 
+    /// Get or set the object's type_params, i.e. ``obj.__type_params__``.
+    str_attr_accessor type_params() const;
+
+
     /// Return the object's current reference count
     ssize_t ref_count() const {
 #ifdef PYPY_VERSION
@@ -2534,6 +2538,11 @@ str_attr_accessor object_api<D>::doc() const {
     return attr("__doc__");
 }
 
+template <typename D>
+str_attr_accessor object_api<D>::type_params() const {
+    return attr("__type_params__");
+}
+
 template <typename D>
 handle object_api<D>::get_type() const {
     return type::handle_of(derived());
diff --git a/include/pybind11/typing.h b/include/pybind11/typing.h
index b0feb9464..077eaaf46 100644
--- a/include/pybind11/typing.h
+++ b/include/pybind11/typing.h
@@ -115,7 +115,7 @@ class Literal : public object {
     PYBIND11_OBJECT_DEFAULT(Literal, object, PyObject_Type)
 };
 
-// Example syntax for creating a TypeVar.
+// Example syntax for creating a type annotation of a TypeVar, ParamSpec, and TypeVarTuple.
 // typedef typing::TypeVar<"T"> TypeVarT;
 template <StringLiteral>
 class TypeVar : public object {
@@ -124,6 +124,41 @@ class TypeVar : public object {
 };
 #endif
 
+
+
+template <typename T>
+class TypeVarObject : public object {
+    PYBIND11_OBJECT_DEFAULT(TypeVarObject, object, PyObject_Type)
+    using object::object;
+    TypeVarObject(const char *name){
+        attr("__name__") = name;
+        attr("__bound__") = make_caster<T>;
+        attr("__constraints__") = pybind11::make_tuple();
+    }
+    // TypeVarObject(const char *name, py::typing::Tuple<pybind11::type, pybind11::ellipse> tuple){
+    //     attr("__name__") = name;
+    //     attr("__bound__") = py::none();
+    //     attr("__constraints__") = tuple;
+    // }
+};
+
+class ParamSpec : public object {
+    PYBIND11_OBJECT_DEFAULT(ParamSpec, object, PyObject_Type)
+    using object::object;
+    ParamSpec(const char *name){
+        attr("__name__") = name;
+        attr("__bound__") = pybind11::none();
+    }
+};
+
+class TypeVarTuple : public object {
+    PYBIND11_OBJECT_DEFAULT(TypeVarTuple, object, PyObject_Type)
+    using object::object;
+    TypeVarTuple(const char *name){
+        attr("__name__") = name;
+    }
+};
+
 PYBIND11_NAMESPACE_END(typing)
 
 PYBIND11_NAMESPACE_BEGIN(detail)
diff --git a/tests/test_pytypes.cpp b/tests/test_pytypes.cpp
index ecb44939a..aa77a65b0 100644
--- a/tests/test_pytypes.cpp
+++ b/tests/test_pytypes.cpp
@@ -923,4 +923,21 @@ TEST_SUBMODULE(pytypes, m) {
 #else
     m.attr("defined_PYBIND11_TYPING_H_HAS_STRING_LITERAL") = false;
 #endif
+
+    struct TypeVarObject {};
+    py::class_<TypeVarObject>(m, "TypeVarObject").type_params() = py::make_tuple(py::typing::TypeVarObject<int>("T"));
+    
+    struct ParamSpec {};
+    py::class_<ParamSpec>(m, "ParamSpec").type_params() = py::make_tuple(py::typing::ParamSpec("P"));
+
+    struct TypeVarTuple {};
+    py::class_<TypeVarTuple>(m, "TypeVarTuple").type_params() = py::make_tuple(py::typing::TypeVarTuple("T"));
+
+
+    struct NoTypeParams {};
+    struct TypeParams {};
+    py::class_<NoTypeParams>(m, "NoTypeParams");
+    // TODO: Use custom objects
+    py::class_<TypeParams>(m, "TypeParams").type_params() = py::make_tuple("foo", 3, py::none());
+    m.def("type_params", []() -> void {}).type_params() = py::make_tuple("foo", 3, py::none());
 }
diff --git a/tests/test_pytypes.py b/tests/test_pytypes.py
index 218092b43..ff1825784 100644
--- a/tests/test_pytypes.py
+++ b/tests/test_pytypes.py
@@ -4,6 +4,7 @@ import contextlib
 import sys
 import types
 
+from typing import TypeVar
 import pytest
 
 import env
@@ -1048,3 +1049,30 @@ def test_typevar(doc):
     assert doc(m.annotate_listT_to_T) == "annotate_listT_to_T(arg0: list[T]) -> T"
 
     assert doc(m.annotate_object_to_T) == "annotate_object_to_T(arg0: object) -> T"
+
+def test_typevar_object():
+    assert len(m.TypeVarObject.__type_params__) == 1
+    type_var = m.TypeVarObject.__type_params__[0]
+    assert type_var.__name__ == "T"
+    assert type_var.__bound__ == int
+    assert type_var.__constraints__ == ()
+
+def test_param_spec():
+    assert len(m.ParamSpec.__type_params__) == 1
+    param_spec = m.ParamSpec.__type_params__[0]
+
+    assert param_spec.__name__ == "P"
+    assert param_spec.__bound__ == None
+
+def test_type_var_tuple():
+    assert len(m.TypeVarTuple.__type_params__) == 1
+    type_var_tuple = m.TypeVarTuple.__type_params__[0]
+
+    assert type_var_tuple.__name__ == "T"
+    with pytest.raises(AttributeError):
+        param_spec.__bound__
+
+def test_type_params():
+    assert m.NoTypeParams.__type_params__ == ()
+    assert m.TypeParams.__type_params__ == ("foo", 3, None)
+    assert m.type_params.__type_params__ == ("foo", 3, None)