Type hinting overhaul.

Author: Kircheneer

diffsync/__init__.py

@@ -16,40 +16,44 @@
 """
 
 from functools import total_ordering
-from typing import Any, Iterator, Iterable, Mapping, Optional, Text, Type
+from typing import Any, Iterator, Optional, Type, List, Dict, Iterable
 
 from .exceptions import ObjectAlreadyExists
 from .utils import intersection, OrderedDefaultDict
 from .enum import DiffSyncActions
 
+# This workaround is used because we are defining a method called `str` in our class definition, which therefore renders
+# the builtin `str` type unusable.
+StrType = str
+
 
 class Diff:
     """Diff Object, designed to store multiple DiffElement object and organize them in a group."""
 
-    def __init__(self):
+    def __init__(self) -> None:
         """Initialize a new, empty Diff object."""
-        self.children = OrderedDefaultDict(dict)
+        self.children = OrderedDefaultDict[StrType, Dict[StrType, DiffElement]](dict)
         """DefaultDict for storing DiffElement objects.
 
         `self.children[group][unique_id] == DiffElement(...)`
         """
         self.models_processed = 0
 
-    def __len__(self):
+    def __len__(self) -> int:
         """Total number of DiffElements stored herein."""
         total = 0
         for child in self.get_children():
             total += len(child)
         return total
 
-    def complete(self):
+    def complete(self) -> None:
         """Method to call when this Diff has been fully populated with data and is "complete".
 
         The default implementation does nothing, but a subclass could use this, for example, to save
         the completed Diff to a file or database record.
         """
 
-    def add(self, element: "DiffElement"):
+    def add(self, element: "DiffElement") -> None:
         """Add a new DiffElement to the changeset of this Diff.
 
         Raises:
@@ -61,15 +65,15 @@ def add(self, element: "DiffElement"):
 
         self.children[element.type][element.name] = element
 
-    def groups(self):
+    def groups(self) -> List[StrType]:
         """Get the list of all group keys in self.children."""
-        return self.children.keys()
+        return list(self.children.keys())
 
     def has_diffs(self) -> bool:
         """Indicate if at least one of the child elements contains some diff.
 
         Returns:
-            bool: True if at least one child element contains some diff
+            True if at least one child element contains some diff
         """
         for group in self.groups():
             for child in self.children[group].values():
@@ -96,15 +100,15 @@ def get_children(self) -> Iterator["DiffElement"]:
             yield from order_method(self.children[group])
 
     @classmethod
-    def order_children_default(cls, children: Mapping) -> Iterator["DiffElement"]:
+    def order_children_default(cls, children: Dict[StrType, "DiffElement"]) -> Iterator["DiffElement"]:
         """Default method to an Iterator for children.
 
         Since children is already an OrderedDefaultDict, this method is not doing anything special.
         """
         for child in children.values():
             yield child
 
-    def summary(self) -> Mapping[Text, int]:
+    def summary(self) -> Dict[StrType, int]:
         """Build a dict summary of this Diff and its child DiffElements."""
         summary = {
             DiffSyncActions.CREATE: 0,
@@ -127,7 +131,7 @@ def summary(self) -> Mapping[Text, int]:
         )
         return summary
 
-    def str(self, indent: int = 0):
+    def str(self, indent: int = 0) -> StrType:
         """Build a detailed string representation of this Diff and its child DiffElements."""
         margin = " " * indent
         output = []
@@ -144,9 +148,9 @@ def str(self, indent: int = 0):
             result = "(no diffs)"
         return result
 
-    def dict(self) -> Mapping[Text, Mapping[Text, Mapping]]:
+    def dict(self) -> Dict[StrType, Dict[StrType, Dict]]:
         """Build a dictionary representation of this Diff."""
-        result = OrderedDefaultDict(dict)
+        result = OrderedDefaultDict[str, Dict](dict)
         for child in self.get_children():
             if child.has_diffs(include_children=True):
                 result[child.type][child.name] = child.dict()
@@ -159,11 +163,11 @@ class DiffElement:  # pylint: disable=too-many-instance-attributes
 
     def __init__(
         self,
-        obj_type: Text,
-        name: Text,
-        keys: Mapping,
-        source_name: Text = "source",
-        dest_name: Text = "dest",
+        obj_type: StrType,
+        name: StrType,
+        keys: Dict,
+        source_name: StrType = "source",
+        dest_name: StrType = "dest",
         diff_class: Type[Diff] = Diff,
     ):  # pylint: disable=too-many-arguments
         """Instantiate a DiffElement.
@@ -177,10 +181,10 @@ def __init__(
             dest_name: Name of the destination DiffSync object
             diff_class: Diff or subclass thereof to use to calculate the diffs to use for synchronization
         """
-        if not isinstance(obj_type, str):
+        if not isinstance(obj_type, StrType):
             raise ValueError(f"obj_type must be a string (not {type(obj_type)})")
 
-        if not isinstance(name, str):
+        if not isinstance(name, StrType):
             raise ValueError(f"name must be a string (not {type(name)})")
 
         self.type = obj_type
@@ -189,18 +193,18 @@ def __init__(
         self.source_name = source_name
         self.dest_name = dest_name
         # Note: *_attrs == None if no target object exists; it'll be an empty dict if it exists but has no _attributes
-        self.source_attrs: Optional[Mapping] = None
-        self.dest_attrs: Optional[Mapping] = None
+        self.source_attrs: Optional[Dict] = None
+        self.dest_attrs: Optional[Dict] = None
         self.child_diff = diff_class()
 
-    def __lt__(self, other):
+    def __lt__(self, other: "DiffElement") -> bool:
         """Logical ordering of DiffElements.
 
         Other comparison methods (__gt__, __le__, __ge__, etc.) are created by our use of the @total_ordering decorator.
         """
         return (self.type, self.name) < (other.type, other.name)
 
-    def __eq__(self, other):
+    def __eq__(self, other: object) -> bool:
         """Logical equality of DiffElements.
 
         Other comparison methods (__gt__, __le__, __ge__, etc.) are created by our use of the @total_ordering decorator.
@@ -216,26 +220,26 @@ def __eq__(self, other):
             # TODO also check that self.child_diff == other.child_diff, needs Diff to implement __eq__().
         )
 
-    def __str__(self):
+    def __str__(self) -> StrType:
         """Basic string representation of a DiffElement."""
         return (
             f'{self.type} "{self.name}" : {self.keys} : '
             f"{self.source_name} → {self.dest_name} : {self.get_attrs_diffs()}"
         )
 
-    def __len__(self):
+    def __len__(self) -> int:
         """Total number of DiffElements in this one, including itself."""
         total = 1  # self
         for child in self.get_children():
             total += len(child)
         return total
 
     @property
-    def action(self) -> Optional[Text]:
+    def action(self) -> Optional[StrType]:
         """Action, if any, that should be taken to remediate the diffs described by this element.
 
         Returns:
-            str: DiffSyncActions ("create", "update", "delete", or None)
+            "create", "update", "delete", or None)
         """
         if self.source_attrs is not None and self.dest_attrs is None:
             return DiffSyncActions.CREATE
@@ -251,7 +255,7 @@ def action(self) -> Optional[Text]:
         return None
 
     # TODO: separate into set_source_attrs() and set_dest_attrs() methods, or just use direct property access instead?
-    def add_attrs(self, source: Optional[Mapping] = None, dest: Optional[Mapping] = None):
+    def add_attrs(self, source: Optional[Dict] = None, dest: Optional[Dict] = None) -> None:
         """Set additional attributes of a source and/or destination item that may result in diffs."""
         # TODO: should source_attrs and dest_attrs be "write-once" properties, or is it OK to overwrite them once set?
         if source is not None:
@@ -260,26 +264,26 @@ def add_attrs(self, source: Optional[Mapping] = None, dest: Optional[Mapping] =
         if dest is not None:
             self.dest_attrs = dest
 
-    def get_attrs_keys(self) -> Iterable[Text]:
+    def get_attrs_keys(self) -> Iterable[StrType]:
         """Get the list of shared attrs between source and dest, or the attrs of source or dest if only one is present.
 
         - If source_attrs is not set, return the keys of dest_attrs
         - If dest_attrs is not set, return the keys of source_attrs
         - If both are defined, return the intersection of both keys
         """
         if self.source_attrs is not None and self.dest_attrs is not None:
-            return intersection(self.dest_attrs.keys(), self.source_attrs.keys())
+            return intersection(list(self.dest_attrs.keys()), list(self.source_attrs.keys()))
         if self.source_attrs is None and self.dest_attrs is not None:
             return self.dest_attrs.keys()
         if self.source_attrs is not None and self.dest_attrs is None:
             return self.source_attrs.keys()
         return []
 
-    def get_attrs_diffs(self) -> Mapping[Text, Mapping[Text, Any]]:
+    def get_attrs_diffs(self) -> Dict[StrType, Dict[StrType, Any]]:
         """Get the dict of actual attribute diffs between source_attrs and dest_attrs.
 
         Returns:
-            dict: of the form `{"-": {key1: <value>, key2: ...}, "+": {key1: <value>, key2: ...}}`,
+            Dictionary of the form `{"-": {key1: <value>, key2: ...}, "+": {key1: <value>, key2: ...}}`,
             where the `"-"` or `"+"` dicts may be absent.
         """
         if self.source_attrs is not None and self.dest_attrs is not None:
@@ -301,13 +305,10 @@ def get_attrs_diffs(self) -> Mapping[Text, Mapping[Text, Any]]:
             return {"+": {key: self.source_attrs[key] for key in self.get_attrs_keys()}}
         return {}
 
-    def add_child(self, element: "DiffElement"):
+    def add_child(self, element: "DiffElement") -> None:
         """Attach a child object of type DiffElement.
 
         Childs are saved in a Diff object and are organized by type and name.
-
-        Args:
-          element: DiffElement
         """
         self.child_diff.add(element)
 
@@ -336,7 +337,7 @@ def has_diffs(self, include_children: bool = True) -> bool:
 
         return False
 
-    def summary(self) -> Mapping[Text, int]:
+    def summary(self) -> Dict[StrType, int]:
         """Build a summary of this DiffElement and its children."""
         summary = {
             DiffSyncActions.CREATE: 0,
@@ -353,7 +354,7 @@ def summary(self) -> Mapping[Text, int]:
             summary[key] += child_summary[key]
         return summary
 
-    def str(self, indent: int = 0):
+    def str(self, indent: int = 0) -> StrType:
         """Build a detailed string representation of this DiffElement and its children."""
         margin = " " * indent
         result = f"{margin}{self.type}: {self.name}"
@@ -377,7 +378,7 @@ def str(self, indent: int = 0):
             result += " (no diffs)"
         return result
 
-    def dict(self) -> Mapping[Text, Mapping[Text, Any]]:
+    def dict(self) -> Dict[StrType, Dict[StrType, Any]]:
         """Build a dictionary representation of this DiffElement and its children."""
         attrs_diffs = self.get_attrs_diffs()
         result = {}

diffsync/diff.py

@@ -14,6 +14,11 @@
 See the License for the specific language governing permissions and
 limitations under the License.
 """
+from typing import TYPE_CHECKING, Union, Any
+
+if TYPE_CHECKING:
+    from diffsync import DiffSyncModel
+    from diffsync.diff import DiffElement
 
 
 class ObjectCrudException(Exception):
@@ -39,7 +44,7 @@ class ObjectStoreException(Exception):
 class ObjectAlreadyExists(ObjectStoreException):
     """Exception raised when trying to store a DiffSyncModel or DiffElement that is already being stored."""
 
-    def __init__(self, message, existing_object, *args, **kwargs):
+    def __init__(self, message: str, existing_object: Union["DiffSyncModel", "DiffElement"], *args: Any, **kwargs: Any):
         """Add existing_object to the exception to provide user with existing object."""
         self.existing_object = existing_object
         super().__init__(message, existing_object, *args, **kwargs)

diffsync/exceptions.py

@@ -15,7 +15,7 @@
 limitations under the License.
 """
 from collections.abc import Iterable as ABCIterable, Mapping as ABCMapping
-from typing import Callable, Iterable, List, Mapping, Optional, Tuple, Type, TYPE_CHECKING
+from typing import Callable, List, Optional, Tuple, Type, TYPE_CHECKING, Dict, Iterable
 
 import structlog  # type: ignore
 
@@ -57,7 +57,7 @@ def __init__(  # pylint: disable=too-many-arguments
         self.total_models = len(src_diffsync) + len(dst_diffsync)
         self.logger.debug(f"Diff calculation between these two datasets will involve {self.total_models} models")
 
-    def incr_models_processed(self, delta: int = 1):
+    def incr_models_processed(self, delta: int = 1) -> None:
         """Increment self.models_processed, then call self.callback if present."""
         if delta:
             self.models_processed += delta
@@ -136,7 +136,9 @@ def diff_object_list(self, src: List["DiffSyncModel"], dst: List["DiffSyncModel"
         return diff_elements
 
     @staticmethod
-    def validate_objects_for_diff(object_pairs: Iterable[Tuple[Optional["DiffSyncModel"], Optional["DiffSyncModel"]]]):
+    def validate_objects_for_diff(
+        object_pairs: Iterable[Tuple[Optional["DiffSyncModel"], Optional["DiffSyncModel"]]]
+    ) -> None:
         """Check whether all DiffSyncModels in the given dictionary are valid for comparison to one another.
 
         Helper method for `diff_object_list`.
@@ -234,15 +236,15 @@ def diff_child_objects(
         diff_element: DiffElement,
         src_obj: Optional["DiffSyncModel"],
         dst_obj: Optional["DiffSyncModel"],
-    ):
+    ) -> DiffElement:
         """For all children of the given DiffSyncModel pair, diff recursively, adding diffs to the given diff_element.
 
         Helper method to `calculate_diffs`, usually doesn't need to be called directly.
 
         These helper methods work in a recursive cycle:
         diff_object_list -> diff_object_pair -> diff_child_objects -> diff_object_list -> etc.
         """
-        children_mapping: Mapping[str, str]
+        children_mapping: Dict[str, str]
         if src_obj and dst_obj:
             # Get the subset of child types common to both src_obj and dst_obj
             src_mapping = src_obj.get_children_mapping()
@@ -308,7 +310,7 @@ def __init__(  # pylint: disable=too-many-arguments
         self.model_class: Type["DiffSyncModel"]
         self.action: Optional[str] = None
 
-    def incr_elements_processed(self, delta: int = 1):
+    def incr_elements_processed(self, delta: int = 1) -> None:
         """Increment self.elements_processed, then call self.callback if present."""
         if delta:
             self.elements_processed += delta
@@ -319,7 +321,7 @@ def perform_sync(self) -> bool:
         """Perform data synchronization based on the provided diff.
 
         Returns:
-            bool: True if any changes were actually performed, else False.
+            True if any changes were actually performed, else False.
         """
         changed = False
         self.base_logger.info("Beginning sync")
@@ -401,14 +403,14 @@ def sync_diff_element(self, element: DiffElement, parent_model: Optional["DiffSy
         return changed
 
     def sync_model(  # pylint: disable=too-many-branches, unused-argument
-        self, src_model: Optional["DiffSyncModel"], dst_model: Optional["DiffSyncModel"], ids: Mapping, attrs: Mapping
+        self, src_model: Optional["DiffSyncModel"], dst_model: Optional["DiffSyncModel"], ids: Dict, attrs: Dict
     ) -> Tuple[bool, Optional["DiffSyncModel"]]:
         """Create/update/delete the current DiffSyncModel with current ids/attrs, and update self.status and self.message.
 
         Helper method to `sync_diff_element`.
 
         Returns:
-            tuple: (changed, model) where model may be None if an error occurred
+            (changed, model) where model may be None if an error occurred
         """
         if self.action is None:
             status = DiffSyncStatus.SUCCESS
@@ -451,7 +453,7 @@ def sync_model(  # pylint: disable=too-many-branches, unused-argument
 
         return (True, dst_model)
 
-    def log_sync_status(self, action: Optional[str], status: DiffSyncStatus, message: str):
+    def log_sync_status(self, action: Optional[str], status: DiffSyncStatus, message: str) -> None:
         """Log the current sync status at the appropriate verbosity with appropriate context.
 
         Helper method to `sync_diff_element`/`sync_model`.