ENH: Run script for Python3 find_package upgrade

Now that cmake FindPython3 can be universally
used, prefer to only use that set of variable
names for identifying the python executables.

Intial procesing with manual cleanup by:

ITK/Utilities/Maintenance/FindPython3_ModernizeCMake.sh

Author: hjmjohnson

CMake/ITKConfig.cmake.in

@@ -141,4 +141,4 @@ set(ITK_WRAP_complex_double @ITK_WRAP_complex_double@)
 set(ITK_WRAP_IMAGE_DIMS "@ITK_WRAP_IMAGE_DIMS@")
 set(ITK_WRAP_VECTOR_COMPONENTS "@ITK_WRAP_VECTOR_COMPONENTS@")
 
-set(ITK_WRAP_PYTHON_VERSION "@PYTHON_VERSION_STRING@")
+set(ITK_WRAP_PYTHON_VERSION "@Python3_VERSION@")

Modules/Bridge/NumPy/CMakeLists.txt

@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.16.3)
 project(ITKBridgeNumPy)
 
-set(ITKBridgeNumPy_SYSTEM_INCLUDE_DIRS "${PYTHON_INCLUDE_DIR}")
+set(ITKBridgeNumPy_SYSTEM_INCLUDE_DIRS "${Python3_INCLUDE_DIRS}")
 
 if(NOT ITK_SOURCE_DIR)
   find_package(ITK REQUIRED)

Modules/ThirdParty/GDCM/src/gdcm/CMakeLists.txt

@@ -455,10 +455,10 @@ endif()
 
 #-----------------------------------------------------------------------------
 # Python install
-#find_package(PythonInterp REQUIRED)
+#find_package(Python3 COMPONENTS Interpreter REQUIRED)
 #macro(GET_PYTHON_SITE_PACKAGE dir)
 #  execute_process(
-#  COMMAND ${PYTHON_EXECUTABLE} "-c" "from distutils import sysconfig; print sysconfig.get_python_lib()"
+#  COMMAND ${Python3_EXECUTABLE} "-c" "from distutils import sysconfig; print sysconfig.get_python_lib()"
 #  #WORKING_DIRECTORY @LIBRARY_OUTPUT_PATH@
 #  RESULT_VARIABLE import_res
 #  OUTPUT_VARIABLE import_output

Modules/ThirdParty/GoogleTest/src/itkgoogletest/googletest/cmake/internal_utils.cmake

@@ -246,12 +246,6 @@ function(cxx_executable name dir libs)
     ${name} "${cxx_default}" "${libs}" "${dir}/${name}.cc" ${ARGN})
 endfunction()
 
-# Sets PYTHONINTERP_FOUND and PYTHON_EXECUTABLE.
-# ITK The PythonInterp package finding contaminates the cmake cache and
-# ITK may find a different version than is use by wrapping or documentation
-# ITK generation.  DO NOT USE find_package(PythonInterp)
-# ITK find_package(PythonInterp)
-
 # cxx_test_with_flags(name cxx_flags libs srcs...)
 #
 # creates a named C++ test that depends on the given libs and is built

Utilities/Doxygen/CMakeLists.txt

@@ -97,7 +97,7 @@ if (ITK_BUILD_DOCUMENTATION)
   file(COPY workbox-cli-config.js serviceWorker.js.in
     DESTINATION ${ITK_BINARY_DIR}/Utilities/Doxygen/)
 
-  execute_process(COMMAND ${PYTHON_EXECUTABLE} "${CMAKE_CURRENT_LIST_DIR}/datetime.py"
+  execute_process(COMMAND ${Python3_EXECUTABLE} "${CMAKE_CURRENT_LIST_DIR}/datetime.py"
      RESULT_VARIABLE CMD_RESULT
      OUTPUT_VARIABLE _DATETIME)
 

Wrapping/macro_files/itk_end_wrap_module.cmake

@@ -392,7 +392,7 @@ ${DO_NOT_WAIT_FOR_THREADS_CALLS}
 
         # Link the modules together
         target_link_libraries(${lib} LINK_PUBLIC ${WRAPPER_LIBRARY_LINK_LIBRARIES})
-        itk_target_link_libraries_with_dynamic_lookup(${lib} LINK_PUBLIC ${PYTHON_LIBRARY})
+        itk_target_link_libraries_with_dynamic_lookup(${lib} LINK_PUBLIC ${Python3_LIBRARIES})
 
         if(USE_COMPILER_HIDDEN_VISIBILITY)
             # Prefer to use target properties supported by newer cmake