[CMake] How to clear variable.

[klaas.holwerda]

Hi,

The find_path documentation says:

If the file in a directory is found the result is stored in the variable 
and the search will not be repeated unless the variable is cleared.

So how do i clear a variable?

The only thing i can work out is:

SET( VAR VAR-NOT-FOUND CACHE INTERNAL "" )

Is that really the way??

Thanks,

Klaas