fix(Python): Use field for dataclass types

To address with Python 3.11:

   ValueError: mutable default <class 'itkwasm.image.ImageType'> for field imageType is not allowed: use default_factory

src/python/itkwasm/itkwasm/image.py

@@ -19,13 +19,16 @@ class ImageType:
     pixelType: PixelTypes = PixelTypes.Scalar
     components: int = 1
 
+def _default_direction() -> ArrayLike:
+    return np.empty((0,), np.float32)
+
 @dataclass
 class Image:
-    imageType: Union[ImageType, Dict] = ImageType()
+    imageType: Union[ImageType, Dict] = field(default_factory=ImageType)
     name: str = 'image'
     origin: Sequence[float] = field(default_factory=list)
     spacing: Sequence[float] = field(default_factory=list)
-    direction: ArrayLike = np.empty((0,), np.float32)
+    direction: ArrayLike = field(default_factory=_default_direction)
     size: Sequence[int] = field(default_factory=list)
     metadata: Dict = field(default_factory=dict)
     data: Optional[ArrayLike] = None
@@ -45,4 +48,4 @@ def __post_init__(self):
             self.direction = np.eye(dimension).astype(np.float32).ravel()
 
         if len(self.size) == 0:
-            self.size += [1,] * dimension
+            self.size += [1,] * dimension

src/python/itkwasm/itkwasm/mesh.py

@@ -1,4 +1,4 @@
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 
 from typing import Optional, Union, Dict
 
@@ -28,7 +28,7 @@ class MeshType:
 
 @dataclass
 class Mesh:
-    meshType: Union[MeshType, Dict] = MeshType()
+    meshType: Union[MeshType, Dict] = field(default_factory=MeshType)
 
     name: str = 'mesh'
 
@@ -47,4 +47,4 @@ class Mesh:
 
     def __post_init__(self):
         if isinstance(self.meshType, dict):
-            self.meshType = MeshType(**self.meshType)
+            self.meshType = MeshType(**self.meshType)

src/python/itkwasm/itkwasm/polydata.py

@@ -1,4 +1,4 @@
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 from typing import Union, Optional, Dict
 
 try:
@@ -7,9 +7,9 @@
     from numpy import ndarray as ArrayLike
 import numpy as np
 
-from .float_types import FloatTypes 
+from .float_types import FloatTypes
 from .int_types import IntTypes
-from .pixel_types import PixelTypes 
+from .pixel_types import PixelTypes
 
 @dataclass
 class PolyDataType:
@@ -23,7 +23,7 @@ class PolyDataType:
 
 @dataclass
 class PolyData:
-    polyDataType: Union[PolyDataType, Dict] = PolyDataType()
+    polyDataType: Union[PolyDataType, Dict] = field(default_factory=PolyDataType)
     name: str = 'polydata'
 
     numberOfPoints: int = 0
@@ -49,4 +49,4 @@ class PolyData:
 
     def __post_init__(self):
         if isinstance(self.polyDataType, dict):
-            self.polyDataType = PolyDataType(**self.polyDataType)
+            self.polyDataType = PolyDataType(**self.polyDataType)