PERF: use importlib_metadata instead of imports for package detection

Author: thewtex

itkwidgets/integrations/itk.py

@@ -1,18 +1,20 @@
 import itkwasm
 
 from packaging import version
+import importlib_metadata
 HAVE_ITK = False
 try:
-    import itk
-    if not hasattr(itk, '__version__') or version.parse(itk.__version__) < version.parse('5.3.0'):
-      raise RuntimeError('itk 5.3 or newer is required. `pip install itk>=5.3.0`')
+    itk_version = importlib_metadata.version('itk')
+    if version.parse(itk_version) < version.parse('5.3.0'):
+        raise RuntimeError('itk 5.3 or newer is required. `pip install itk>=5.3.0`')
     HAVE_ITK = True
-except ImportError:
+except importlib_metadata.PackageNotFoundError:
     pass
-    
+
 
 if HAVE_ITK:
     def itk_group_spatial_object_to_wasm_point_set(point_set):
+        import itk
         point_set_dict = itk.dict_from_pointset(point_set)
         wasm_point_set = itkwasm.PointSet(**point_set_dict)
         return wasm_point_set

itkwidgets/integrations/pytorch.py

@@ -1,6 +1,8 @@
+import importlib_metadata
+
 HAVE_TORCH = False
 try:
-    import torch
+    importlib_metadata.metadata("torch")
     HAVE_TORCH = True
-except ImportError:
+except importlib_metadata.PackageNotFoundError:
     pass

itkwidgets/integrations/vtk.py

@@ -1,15 +1,17 @@
+import importlib_metadata
+
 HAVE_VTK = False
 try:
-    import vtk
+    importlib_metadata.metadata("vtk")
     HAVE_VTK = True
-    from vtk.util.numpy_support import vtk_to_numpy
-except ImportError:
+except importlib_metadata.PackageNotFoundError:
     pass
 
-from ngff_zarr import ngff_image, to_ngff_image
+from ngff_zarr import to_ngff_image
 
 
 def vtk_image_to_ngff_image(image):
+    from vtk.util.numpy_support import vtk_to_numpy
     array = vtk_to_numpy(image.GetPointData().GetScalars())
     dimensions = list(image.GetDimensions())
     array.shape = dimensions[::-1]
@@ -25,5 +27,6 @@ def vtk_image_to_ngff_image(image):
     return ngff_image
 
 def vtk_polydata_to_vtkjs(point_set):
+    from vtk.util.numpy_support import vtk_to_numpy
     array = vtk_to_numpy(point_set.GetPoints().GetData())
     return array

itkwidgets/integrations/xarray.py

@@ -1,15 +1,17 @@
+import importlib_metadata
+
 HAVE_XARRAY = False
 try:
-    import xarray
+    importlib_metadata.metadata("xarray")
     HAVE_XARRAY = True
-except ImportError:
+except importlib_metadata.PackageNotFoundError:
     pass
 
 HAVE_MULTISCALE_SPATIAL_IMAGE = False
 try:
-    import multiscale_spatial_image
+    importlib_metadata.metadata("multiscale-spatial-image")
     HAVE_MULTISCALE_SPATIAL_IMAGE = True
-except ImportError:
+except importlib_metadata.PackageNotFoundError:
     pass
 
 def xarray_data_array_to_numpy(data_array):

pyproject.toml

@@ -39,6 +39,7 @@ dependencies = [
     "itkwasm >= 1.0b.78",
     "imjoy-rpc >= 0.5.42",
     "imjoy-utils >= 0.1.2",
+    "importlib_metadata",
     "ngff-zarr[dask-image] >= 0.4.3",
     "numcodecs",
     "zarr",