| """ |
| A script that replaces an old file with a new one, only if the contents |
| actually changed. If not, the new file is simply deleted. |
| |
| This avoids wholesale rebuilds when a code (re)generation phase does not |
| actually change the in-tree generated code. |
| """ |
| |
| import os |
| import sys |
| |
| |
| def main(old_path, new_path): |
| with open(old_path, 'rb') as f: |
| old_contents = f.read() |
| with open(new_path, 'rb') as f: |
| new_contents = f.read() |
| if old_contents != new_contents: |
| os.replace(new_path, old_path) |
| else: |
| os.unlink(new_path) |
| |
| |
| if __name__ == '__main__': |
| if len(sys.argv) != 3: |
| print("Usage: %s <path to be updated> <path with new contents>" % (sys.argv[0],)) |
| sys.exit(1) |
| main(sys.argv[1], sys.argv[2]) |
