1 files changed, 51 insertions, 0 deletions
diff --git a/tools/cru-py/cru/util/_const.py b/tools/cru-py/cru/util/_const.py
new file mode 100644
index 0000000..ea67450
--- /dev/null
+++ b/tools/cru-py/cru/util/_const.py
@@ -0,0 +1,51 @@
+from typing import Any
+
+
+def make_unique_object() -> Any:
+    class _CruUnique:
+        _i = False
+
+        def __init__(self):
+            if self._i:
+                raise ValueError("_CruAttrNotSet is a singleton!")
+            self._i = True
+
+        def __copy__(self):
+            return self
+
+        def __eq__(self, other):
+            return isinstance(other, _CruUnique)
+
+    v = _CruUnique()
+
+    return v
+
+
+def make_bool_unique_object(b: bool) -> Any:
+    class _CruBoolUnique:
+        _i = False
+
+        def __init__(self):
+            super().__init__(b)
+            if self._i:
+                raise ValueError("_CruAttrNotSet is a singleton!")
+            self._i = True
+
+        def __copy__(self):
+            return self
+
+        def __eq__(self, other):
+            return isinstance(other, _CruBoolUnique) or b == other
+
+        def __bool__(self):
+            return b
+
+    v = _CruBoolUnique()
+
+    return v
+
+
+CRU_NOT_FOUND = make_bool_unique_object(False)
+CRU_USE_DEFAULT = make_unique_object()
+CRU_DONT_CHANGE = make_unique_object()
+CRU_PLACEHOLDER = make_unique_object()