Advantages of using CMake option command rather than set?

Question

I think the option command is redundant because it can be replaced by the set command. What are the benefits I could get when I use the option command?

Answer 1

A variable defined in an option command appears as a boolean choice in the CMake GUI or when running CMake interactively using cmake -i. This is not the case for a variable defined using set unless CACHE is used and the type is not INTERNAL.

Also, the CMakeDependentOption module allows for specifying dependencies between options.