use status names.

Author: d-w-moore

irods/data_object.py

@@ -1,5 +1,6 @@
 import ast
 import datetime
+import enum
 import io
 import logging
 import os
@@ -42,9 +43,28 @@ def __repr__(self):
         return "<{}.{} {}>".format(self.__class__.__module__, self.__class__.__name__, self.resource_name)
 
 
-_REPL_STATUSES = (1, 0, 2, 3, 4)
-_REFERENCE_DATETIME = datetime.datetime(1970, 1, 1, 0, 0, 0, tzinfo=datetime.timezone.utc)
+class _repl_status(enum.Enum):
+    STALE_REPLICA, \
+    GOOD_REPLICA, \
+    INTERMEDIATE_REPLICA, \
+    READ_LOCKED, \
+    WRITE_LOCKED = range(5)
+
 
+# Ordering by fitness for use/interface, for various replica status values.
+_REPL_STATUSES = tuple(
+    getattr(_repl_status, ident).value for ident in (
+        "GOOD_REPLICA", 
+        "STALE_REPLICA",
+        "INTERMEDIATE_REPLICA",
+        "READ_LOCKED",
+        "WRITE_LOCKED",
+    )
+)
+
+# An appropriate reference datetime value for gauging replica age as part of
+# the default sort key in PRC4 and onward.
+_REFERENCE_DATETIME = datetime.datetime(1970, 1, 1, 0, 0, 0, tzinfo=datetime.timezone.utc)
 
 def _REPLICA_NUMBER_SORT_KEY_FN(row):
     return row[DataObject.replica_number]