refactors put better

Author: huettenhain

refinery/lib/types.py

@@ -252,3 +252,13 @@ def __iter__(self):
 
     def __next__(self):
         return self
+
+
+class _NoDefault(metaclass=Singleton):
+    pass
+
+
+NoDefault = _NoDefault()
+"""
+A sentinel singleton that can be used as a no-default marker when "None" is a valid option.
+"""

refinery/units/meta/put.py

@@ -4,11 +4,9 @@
 
 from refinery.lib.meta import check_variable_name
 from refinery.lib.tools import isbuffer, typename
-from refinery.lib.types import Param, isq
+from refinery.lib.types import NoDefault, Param, isq
 from refinery.units import Arg, Chunk, Unit
 
-_EMPTY = object()
-
 
 class put(Unit):
     """
@@ -18,15 +16,15 @@ class put(Unit):
     def __init__(
         self,
         name: Param[str, Arg.String(help='The name of the variable to be used.')],
-        value: Param[isq, Arg.NumSeq(check=False, help=(
+        value: Param[isq | NoDefault, Arg.NumSeq(check=False, help=(
             'The value for the variable. If no value is given, the entire current chunk is stored.'
-        ))] = _EMPTY
+        ))] = NoDefault
     ):
         super().__init__(name=check_variable_name(name), value=value)
 
     def process(self, data: Chunk):
         value = self.args.value
-        if value is _EMPTY:
+        if value is NoDefault:
             value = data
         if not isinstance(value, (int, float)) and not isbuffer(value):
             try: