SET(MYVAR "A good var")
SET(MYVAR2 "blah")

IF("${MYVAR}" MATCHES "^${MYVAR}$")
  MESSAGE("MATCHES -- MYVAR = ${MYVAR}")
ELSE("${MYVAR}" MATCHES "^${MYVAR}$")
  MESSAGE("NO MATCHES ** MYVAR = ${MYVAR}")
ENDIF("${MYVAR}" MATCHES "^${MYVAR}$")

SET(MYVAR "MYVAR2")
MESSAGE("Look that one = double-dollar = ${${MYVAR}} / single-dollar = ${MYVAR}")

IF("${MYVAR}" MATCHES "^${MYVAR}$")
  MESSAGE("MATCHES -- MYVAR = ${MYVAR}")
ELSE("${MYVAR}" MATCHES "^${MYVAR}$")
  MESSAGE("NO MATCHES ** MYVAR = ${MYVAR}")
ENDIF("${MYVAR}" MATCHES "^${MYVAR}$")