Type hint _from_geojson with more judicious uses of cast()

Author: JamesParrott

src/shapefile.py

@@ -989,7 +989,7 @@ def __geo_interface__(self) -> GeoJSONHomogeneousGeometryObject:
         )
 
     @staticmethod
-    def _from_geojson(geoj) -> Shape:
+    def _from_geojson(geoj: GeoJSONHomogeneousGeometryObject) -> Shape:
         # create empty shape
         # set shapeType
         geojType = geoj["type"] if geoj else "Null"
@@ -998,18 +998,26 @@ def _from_geojson(geoj) -> Shape:
         else:
             raise GeoJSON_Error(f"Cannot create Shape from GeoJSON type '{geojType}'")
 
+        coordinates = geoj["coordinates"]
+
+        if coordinates == ():
+            raise GeoJSON_Error(f"Cannot create non-Null Shape from: {coordinates=}")
+
+        points: PointsT
+        parts: list[int]
+
         # set points and parts
         if geojType == "Point":
-            points = [geoj["coordinates"]]
+            points = [cast(PointT, coordinates)]
             parts = [0]
         elif geojType in ("MultiPoint", "LineString"):
-            points = geoj["coordinates"]
+            points = cast(PointsT, coordinates)
             parts = [0]
         elif geojType == "Polygon":
             points = []
             parts = []
             index = 0
-            for i, ext_or_hole in enumerate(geoj["coordinates"]):
+            for i, ext_or_hole in enumerate(cast(list[PointsT], coordinates)):
                 # although the latest GeoJSON spec states that exterior rings should have
                 # counter-clockwise orientation, we explicitly check orientation since older
                 # GeoJSONs might not enforce this.
@@ -1026,15 +1034,15 @@ def _from_geojson(geoj) -> Shape:
             points = []
             parts = []
             index = 0
-            for linestring in geoj["coordinates"]:
+            for linestring in cast(list[PointsT], coordinates):
                 points.extend(linestring)
                 parts.append(index)
                 index += len(linestring)
         elif geojType == "MultiPolygon":
             points = []
             parts = []
             index = 0
-            for polygon in geoj["coordinates"]:
+            for polygon in cast(list[list[PointsT]], coordinates):
                 for i, ext_or_hole in enumerate(polygon):
                     # although the latest GeoJSON spec states that exterior rings should have
                     # counter-clockwise orientation, we explicitly check orientation since older
@@ -3591,9 +3599,9 @@ def shape(
         # Check is shape or import from geojson
         if not isinstance(s, Shape):
             if hasattr(s, "__geo_interface__"):
-                shape_dict = cast(dict, s.__geo_interface__)
+                shape_dict = cast(GeoJSONHomogeneousGeometryObject, s.__geo_interface__)
             if isinstance(s, dict):
-                shape_dict = s
+                shape_dict = cast(GeoJSONHomogeneousGeometryObject, s)
             else:
                 raise TypeError(
                     "Can only write Shape objects, GeoJSON dictionaries, "