CMake and configure_file: what if I need $ONLY instead of @ONLY? -

as documentation of configure_file, has useful @only parameter used to:

restrict variable replacement references of form @var@. useful configuring scripts use ${var} syntax.

so far good.

now i'm in case i've file contains both @foo@ , ${bar} , want replace s{bar} variable comes cmakelists.tx. on other side don't want configure_file tries replace @foo@.
in other terms, need $only parameter works @only opposite case.

is there chance can have right now?
tried putting backslashes in front of @, way obtain file contains couple of \@ , not need.

at least found solution works, if i'm not sure that's best approach ever.
leave answer future readers in case no solutions come up.

suppose line elaborated looks this:

@donttouchme@/${project_name} 

to able skip @donttouchme@ part when pass file configure_file, can change line follows:

@@workaround@donttouchme@workaround@@/${project_name} 

configure_file match , replace @workaround@ parts empty string , forget other @ around, obtain following line after substitution:

@donttouchme@/thenameoftheproject 

quite dirty , break out future releases of cmake exploits bug (uhm, i'm not sure can call way actually) of tool.
anyway, works , can viable approach out there still looking possible solution.