added nb::globals() function wrapping PyEval_GetGlobals() (#311)

docs/changelog.rst

@@ -15,6 +15,12 @@ case, both modules must use the same nanobind ABI version, or they will be
 isolated from each other. Releases that don't explicitly mention an ABI version
 below inherit that of the preceding release.
 
+Version 1.7.0 (TBA)
+-------------------
+
+* Added :cpp:func:`nb::globals() <globals>`. (PR `#311
+  <https://github.com/wjakob/nanobind/pull/311>`__).
+
 Version 1.6.2 (Oct 3, 2023)
 -------------------
 

include/nanobind/nb_misc.h

@@ -39,6 +39,13 @@ inline void set_implicit_cast_warnings(bool value) noexcept {
     detail::set_implicit_cast_warnings(value);
 }
 
+inline dict globals() {
+    PyObject *p = PyEval_GetGlobals();
+    if (!p)
+        detail::raise("nanobind::globals(): no frame is currently executing!");
+    return borrow<dict>(p);
+}
+
 inline bool is_alive() noexcept {
     return detail::is_alive();
 }

tests/test_globals.cpp

@@ -0,0 +1,15 @@
+#include <nanobind/nanobind.h>
+
+namespace nb = nanobind;
+
+NB_MODULE(test_eval_ext, m) {
+    m.def("globals_contains_a", []() {
+        return nb::globals().contains("a");
+    });
+
+    m.def("globals_add_b", []() {
+        auto globals = nb::globals();
+        globals["b"] = 123;
+        return globals;
+    });
+}

tests/test_globals.py

@@ -0,0 +1,10 @@
+
+def test_read_globals():
+    a = 1
+    assert m.globals_contains_a()
+
+
+def test_write_globals():
+    assert "b" not in globals()
+    m.globals_add_b()
+    assert globals()["b"] == 123