rename & test

qlib/finco/utils.py

@@ -3,16 +3,23 @@ import json
 from fuzzywuzzy import fuzz
 
 
-class Singleton(type):
+class SingletonMeta(type):
     _instance = None
 
     def __call__(cls, *args, **kwargs):
         if cls._instance is None:
-            cls._instance = super(Singleton, cls).__call__(*args, **kwargs)  
+            cls._instance = super(SingletonMeta, cls).__call__(*args, **kwargs)
         return cls._instance
 
-class SingletonBaseClass(metaclass=Singleton):  
+
-    pass
+class SingletonBaseClass(metaclass=SingletonMeta):
+    """
+    Because we try to support defining Singleton with `class A(SingletonBaseClass)` instead of `A(metaclass=SingletonMeta)`
+    This class becomes necessary
+
+    """
+    # TODO: Add move this class to Qlib's general utils.
+
 
 def parse_json(response):
     try:

tests/finco/test_utils.py

@@ -0,0 +1,23 @@
+import unittest
+from qlib.finco.utils import SingletonBaseClass
+
+
+class TimeUtils(unittest.TestCase):
+
+    def test_singleton(self):
+        # self.assertEqual(self.to_str(data.tail()), self.to_str(res))
+        closure_checker = []
+
+        class A(SingletonBaseClass):
+
+            def __init__(self) -> None:
+                closure_checker.append(0)
+
+        A()
+        self.assertEqual(len(closure_checker), 1)
+        A()
+        self.assertEqual(len(closure_checker), 1)
+
+
+if __name__ == "__main__":
+    unittest.main()