REFACTOR-modin-project#2059: Make computed default be on demand

Signed-off-by: Vasilij Litvinov <[email protected]>

modin/config/envvars.py

@@ -54,7 +54,8 @@ class Engine(EnvironmentVariable, type=str):
     varname = "MODIN_ENGINE"
     choices = ("Ray", "Dask", "Python")
 
-    def __compute_default():
+    @classmethod
+    def _get_default(cls):
         if IsDebug.get():
             return "Python"
         try:
@@ -84,9 +85,6 @@ def __compute_default():
             )
         return "Dask"
 
-    default = __compute_default()
-    del __compute_default
-
 
 class Backend(EnvironmentVariable, type=str):
     """

modin/config/pubsub.py

@@ -81,14 +81,18 @@ def subscribe(cls, callback):
         cls._subs.append(callback)
         callback(cls)
 
+    @classmethod
+    def _get_default(cls):
+        return cls.default
+
     @classmethod
     def get(cls):
         if cls._value is _UNSET:
             # get the value from env
             try:
                 raw = cls._get_raw_from_config()
             except KeyError:
-                cls._value = cls.default
+                cls._value = cls._get_default()
             else:
                 cls._value = _TYPE_PARAMS[cls.type].decode(raw)
         return cls._value