BUG: snake case functions are erased

When re-running cmake, the dependancies required
to append the `snake_case_functions` to the
`ITK*Config.py` files was incorrect.

Resolves #515

Wrapping/Generators/Python/CMakeLists.txt

@@ -362,16 +362,22 @@ macro(itk_end_wrap_module_python)
   if(NOT "${WRAPPER_LIBRARY_NAME}" STREQUAL "ITKPyBase")
     set(ITK_WRAP_PYTHON_CONFIGURATION_DEPENDS "'ITKPyBase', ${ITK_WRAP_PYTHON_CONFIGURATION_DEPENDS}")
     set(ITK_WRAP_PYTHON_LIBRARY_IMPORTS "import itk.ITKPyBasePython\n${ITK_WRAP_PYTHON_LIBRARY_IMPORTS}")
+    set(ITK_WRAP_PYTHON_SNAKE_CASE "${ITK_WRAP_PYTHON_BINARY_DIR}/Configuration/${WRAPPER_LIBRARY_NAME}_snake_case.py")
+  else()
+    unset(ITK_WRAP_PYTHON_SNAKE_CASE)
   endif()
+  set(ITK_WRAP_PYTHON_LIBRARY_CONFIG_FILE "${ITK_WRAP_PYTHON_BINARY_DIR}/Configuration/${WRAPPER_LIBRARY_NAME}Config.py")
 
   # and create the file, with the var ITK_WRAP_PYTHON_CONFIGURATION_TEMPLATES and
   # ITK_WRAP_PYTHON_CONFIGURATION_DEPENDS created earlier
   configure_file("${ITK_WRAP_PYTHON_SOURCE_DIR}/ModuleConfig.py.in"
-    "${ITK_WRAP_PYTHON_BINARY_DIR}/Configuration/${WRAPPER_LIBRARY_NAME}Config.py"
+    "${ITK_WRAP_PYTHON_LIBRARY_CONFIG_FILE}"
     @ONLY)
+
   WRAP_ITK_PYTHON_BINDINGS_INSTALL(/itk/Configuration
     "${WRAPPER_LIBRARY_NAME}"
-    "${ITK_WRAP_PYTHON_BINARY_DIR}/Configuration/${WRAPPER_LIBRARY_NAME}Config.py"
+    "${ITK_WRAP_PYTHON_LIBRARY_CONFIG_FILE}"
+    "${ITK_WRAP_PYTHON_SNAKE_CASE}"
   )
 
   set(ITK_WRAP_PYTHON_GLOBAL_TIMESTAMP_DECLS )

Wrapping/Generators/Python/itkBase.py

@@ -246,4 +246,11 @@ def cleanup(self):
         path = os.path.join(d + os.sep + "Configuration", conf)
         with open(path, "rb") as modulefile:
             exec(modulefile.read(), data)
+        snake_data = {}
+        snake_conf = module + '_snake_case.py'
+        snake_path = os.path.join(d + os.sep + "Configuration", snake_conf)
+        if os.path.exists(snake_path):
+          with open(snake_path, "rb") as snake_modulefile:
+              exec(snake_modulefile.read(), snake_data)
+        data.update(snake_data)
         module_data[module] = data

Wrapping/Generators/SwigInterface/CMakeLists.txt

@@ -334,6 +334,7 @@ macro(itk_end_wrap_module_swig_interface)
   set(deps_imports )
 
   list(APPEND mdx_opts --mdx "${WRAPPER_MASTER_INDEX_OUTPUT_DIR}/${WRAPPER_LIBRARY_NAME}.mdx")
+
   foreach(dep ${WRAPPER_LIBRARY_DEPENDS})
     list(APPEND mdx_opts --mdx "${WRAP_ITK_TYPEDEFS_DIRECTORY}/${dep}.mdx")
     list(APPEND deps_imports "%import ${dep}.i\n")
@@ -348,15 +349,20 @@ macro(itk_end_wrap_module_swig_interface)
 
   list(LENGTH i_files number_interface_files)
   if(number_interface_files GREATER 0)
+    # NOTE:  snake_case_config_file is both an input and an output to this command.
+    #        the ${IGENERATOR} script appends to this file.
+    set(snake_case_config_file
+        "${WRAPPER_LIBRARY_OUTPUT_DIR}/Generators/Python/Configuration/${WRAPPER_LIBRARY_NAME}_snake_case.py")
     add_custom_command(
-      OUTPUT ${i_files} ${typedef_files} ${idx_files}
+      OUTPUT ${i_files} ${typedef_files} ${idx_files} ${snake_case_config_file}
       COMMAND ${Python3_EXECUTABLE} ${IGENERATOR}
         ${mdx_opts}
         ${swig_libs}
         -w1 -w3 -w51 -w52 -w53 -w54
         -A protected -A private
         -p ${PYGCCXML_DIR}
         -g ${CASTXML_EXECUTABLE}
+        --snake-case-file "${snake_case_config_file}"
         --interface-output-dir "${WRAPPER_MASTER_INDEX_OUTPUT_DIR}"
         --library-output-dir "${WRAPPER_LIBRARY_OUTPUT_DIR}"
         --submodule-order "${WRAPPER_SUBMODULE_ORDER}"

Wrapping/Generators/SwigInterface/igenerator.py

@@ -1146,6 +1146,13 @@ def create_interfacefile(self, interfaceFile, idxFile, wrappersNamespace):
         dest="submodule_order",
         help="List of submodules that must be wrapped in the given order",
     )
+    argParser.add_argument(
+        "-a",
+        "--snake-case-file",
+        action="store",
+        dest="snake_case_file",
+        help="The configuration file to be appended to if snake_case_functions are found",
+    )
     options = argParser.parse_args()
 
     sys.path.insert(1, options.pygccxml_path)
@@ -1234,20 +1241,22 @@ def generate_swig_input(moduleName):
     for moduleName in moduleNames:
         generate_swig_input(moduleName)
 
-    config_file = os.path.join(
-        options.library_output_dir,
-        "Generators",
-        "Python",
-        "Configuration",
-        os.path.basename(options.mdx[0])[:-4] + "Config.py",
-    )
-    with open(config_file, "a") as ff:
-        ff.write("snake_case_functions = (")
-        # Ensure that the functions are sorted alphabetically to ensure consistency
-        # in the generated file structure.
-        sorted_snake_case_process_object_functions = sorted(
-            snake_case_process_object_functions
+    snake_case_file = options.snake_case_file
+    main_config_file = snake_case_file.replace("_snake_case.py","Config.py")
+    if not os.path.exists(main_config_file):
+        print(
+            f"ERROR: required {main_config_file} file does not exist\n"
+            f"can not append to {snake_case_file}\n"
         )
-        for function in sorted_snake_case_process_object_functions:
-            ff.write("'" + function + "', ")
-        ff.write(")\n")
+        sys.exit(-1)
+    else:
+        with open(snake_case_file, "a") as ff:
+            ff.write("snake_case_functions = (")
+            # Ensure that the functions are sorted alphabetically to ensure consistency
+            # in the generated file structure.
+            sorted_snake_case_process_object_functions = sorted(
+                snake_case_process_object_functions
+            )
+            for function in sorted_snake_case_process_object_functions:
+                ff.write("'" + function + "', ")
+            ff.write(")\n")