Gating network behind compile flag

tools/color.py

@@ -1,6 +1,7 @@
 import argparse
 import csv
-import os
+
+from tools.writeifchanged import write_if_changed
 
 parser = argparse.ArgumentParser(description="Color CSV to .h defines")
 parser.add_argument("--csv", required=True, help="Path to color CSV file")
@@ -79,6 +80,4 @@ for line in "\n".join(js).rstrip().splitlines():
 out[-1] = out[-1].rstrip(" \\")
 out.append("")
 
-os.makedirs(os.path.dirname(args.output), exist_ok=True)
-with open(args.output, "w", encoding="utf-8") as f:
-  f.write("\n".join(out))
+write_if_changed(args.output, "\n".join(out))

tools/item.py

@@ -1,6 +1,7 @@
 import argparse
 import json
-import os
+
+from tools.writeifchanged import write_if_changed
 
 parser = argparse.ArgumentParser(description="Item JSON to .h defines")
 parser.add_argument("--json", required=True, help="Path to item JSON file")
@@ -109,6 +110,4 @@ out += [
   "",
 ]
 
-os.makedirs(os.path.dirname(args.output), exist_ok=True)
-with open(args.output, "w", encoding="utf-8") as f:
-  f.write("\n".join(out))
+write_if_changed(args.output, "\n".join(out))

tools/run_python/CMakeLists.txt

@@ -4,11 +4,16 @@
 # https://opensource.org/licenses/MIT
 
 function(dusk_run_python CMAKE_TARGET_NAME PYTHON_MODULE)
+  cmake_parse_arguments(DUSK_RUN_PYTHON "" "OUTPUT" "DEPENDS;ARGS" ${ARGN})
   find_package(Python3 COMPONENTS Interpreter REQUIRED)
 
-  add_custom_target(${CMAKE_TARGET_NAME} ALL
+  add_custom_command(
+    OUTPUT ${DUSK_RUN_PYTHON_OUTPUT}
     WORKING_DIRECTORY ${DUSK_ROOT_DIR}
     COMMAND
-      ${Python3_EXECUTABLE} -m ${PYTHON_MODULE} ${ARGN}
+      ${Python3_EXECUTABLE} -m ${PYTHON_MODULE} ${DUSK_RUN_PYTHON_ARGS}
+    DEPENDS ${DUSK_RUN_PYTHON_DEPENDS}
+    VERBATIM
   )
+  add_custom_target(${CMAKE_TARGET_NAME} DEPENDS ${DUSK_RUN_PYTHON_OUTPUT})
 endfunction()

tools/writeifchanged.py

@@ -0,0 +1,13 @@
+import os
+
+def write_if_changed(path, content):
+  try:
+    with open(path, "r", encoding="utf-8") as f:
+      if f.read() == content:
+        return
+  except FileNotFoundError:
+    pass
+
+  os.makedirs(os.path.dirname(path), exist_ok=True)
+  with open(path, "w", encoding="utf-8") as f:
+    f.write(content)