From 1f4c4204d0ebc45432b61ecf713af5454f53de40 Mon Sep 17 00:00:00 2001
From: Thomas Krijnen <t.krijnen@gmail.com>
Date: Thu, 15 Jan 2026 13:13:51 +0100
Subject: [PATCH] Re-enable setting logical with UNKNOWN in python

---
 .../test/test_entity_instance.py                   | 14 ++++++++++++++
 src/ifcwrap/IfcParseWrapper.i                      |  8 ++++++++
 2 files changed, 22 insertions(+)

diff --git a/src/ifcopenshell-python/test/test_entity_instance.py b/src/ifcopenshell-python/test/test_entity_instance.py
index f8a1b773e1..935a60c3fe 100644
--- a/src/ifcopenshell-python/test/test_entity_instance.py
+++ b/src/ifcopenshell-python/test/test_entity_instance.py
@@ -76,3 +76,17 @@ def test_equality():
     assert f[1] == g[1]
     g[1].Coordinates = (1., 0.)
     assert f[1] != g[1]
+
+def test_setting_logical():
+    f = ifcopenshell.file()
+    inst = f.createIfcPresentationLayerWithStyle(LayerOn="UNKNOWN")
+    assert inst.LayerOn == "UNKNOWN"
+    assert '.U.' in str(inst)
+    with pytest.raises(Exception):
+        inst.LayerOn = "SOME_OTHER_STRING"
+    inst.LayerOn = False
+    assert inst.LayerOn is False
+    assert '.F.' in str(inst)
+    inst.LayerOn = True
+    assert inst.LayerOn is True
+    assert '.T.' in str(inst)
diff --git a/src/ifcwrap/IfcParseWrapper.i b/src/ifcwrap/IfcParseWrapper.i
index eabdbb5be5..c4514fb8b6 100644
--- a/src/ifcwrap/IfcParseWrapper.i
+++ b/src/ifcwrap/IfcParseWrapper.i
@@ -789,6 +789,14 @@ private:
 				boost::logic::tribool t(boost::logic::indeterminate);
 				if (PyBool_Check(value)) {
 					t = (value == Py_True);
+				} else if (PyUnicode_Check(value)) {
+					if (PyObject* ascii = PyUnicode_AsEncodedString(value, "UTF-8", "strict")) {
+						// value is kept as indeterminate
+						if (strcmp(PyBytes_AS_STRING(ascii), "UNKNOWN") != 0) {
+							throw IfcParse::IfcException("Attribute not set");
+						}
+						Py_DECREF(ascii);
+					}
 				} else {
 					long v = to_index_long(value);
 					if (v == 0) t = false;