make it a class

python_modules/dagster/dagster/_core/execution/context/compute.py

@@ -12,7 +12,6 @@
     Iterator,
     List,
     Mapping,
-    NamedTuple,
     Optional,
     Sequence,
     Set,
@@ -1416,12 +1415,45 @@ def _get_deprecation_kwargs(attr: str):
     return deprecation_kwargs
 
 
-class PartitionInfo(NamedTuple):  # TODO - this is a bad name, figure out something else
-    key: Optional[str]
-    keys: Sequence[str]
-    key_range: PartitionKeyRange
-    time_window: Optional[TimeWindow]
-    definition: PartitionsDefinition
+class PartitionInfo:  # TODO - this is a bad name, figure out something else
+    def __init__(
+        self,
+        key: Optional[str],
+        keys: Sequence[str],
+        key_range: PartitionKeyRange,
+        time_window: Optional[TimeWindow],
+        definition: PartitionsDefinition,
+    ):
+        self._key = key
+        self._keys = keys
+        self._key_range = key_range
+        self._time_window = time_window
+        self._definition = definition
+
+    @property
+    def key(self) -> str:
+        if self._key is None:
+            raise DagsterInvariantViolationError(
+                "Cannot access partition key for a partitioned run with a range of partitions."
+                " Call key_range instead."
+            )
+        return self._key
+
+    @property
+    def keys(self) -> Sequence[str]:
+        return self._keys
+
+    @property
+    def key_range(self) -> PartitionKeyRange:
+        return self._key_range
+
+    @property
+    def time_window(self) -> TimeWindow:
+        if self._time_window is None:
+            raise ValueError(
+                "Tried to get partition time window for an asset that is not time-partitioned."
+            )
+        return self._time_window
 
 
 class AssetExecutionContext(OpExecutionContext):