CMAKE: Conditionally Initializing a Cache Variable dependant on the Generator Type - build-process

Question

I currently have a basic Cmake file that sets certain library directories. I would like to conditionally intitalise based on the target generator -- in my case the generator determines which base directories to use (64-bit visual studio generator vs a regular visual studio generator).
My CMakeLists file looks as follows:
PROJECT(STAT_AUTH)
CMAKE_MINIMUM_REQUIRED(VERSION 2.8)
SET(BOOST_DIR "c:\\dev_32\\Boost" CACHE PATH "The Boost Directory Path")
SET(PROTOBUF_DIR "c:\\dev_32\\Protobuf" CACHE PATH "The Protobuf directory Path")
SET(OPENSSL_DIR "c:\\dev_32\\OpenSSL" CACHE PATH "The OpenSSL Directory Path"
How do I conditionally initialise the variables so they get set to 64-bit versions when I generate to 64-bit generators. The default setting should show up in the Cmake Gui / ccmake before I choose the "generate" option.

Answer 1

Try:
if(CMAKE_SIZEOF_VOID_P MATCHES 4)
SET(BOOST_DIR "c:\\dev_32\\Boost" CACHE PATH "The Boost Directory Path")
SET(PROTOBUF_DIR "c:\\dev_32\\Protobuf" CACHE PATH "The Protobuf directory Path")
SET(OPENSSL_DIR "c:\\dev_32\\OpenSSL" CACHE PATH "The OpenSSL Directory Path"
else()
SET(BOOST_DIR "c:\\dev_64\\Boost" CACHE PATH "The Boost Directory Path")
SET(PROTOBUF_DIR "c:\\dev_64\\Protobuf" CACHE PATH "The Protobuf directory Path")
SET(OPENSSL_DIR "c:\\dev_64\\OpenSSL" CACHE PATH "The OpenSSL Directory Path"
endif()

Answer 2

For Windows the following syntax is apt. CMAKE_CL_64 defines the x86_64 compiler specifically.
if(MSVC)
if(CMAKE_CL_64)
SET(BOOST_DIR "c:\\dev_64\\Boost" CACHE PATH "The Boost Directory Path")
SET(PROTOBUF_DIR "c:\\dev_64\\Protobuf" CACHE PATH "The Protobuf directory Path")
SET(OPENSSL_DIR "c:\\dev_64\\OpenSSL" CACHE PATH "The OpenSSL Directory Path")
SET(DEPLOY_DIR "c:\\root_64" CACHE PATH "The Deploy Path for the components built" )
else()
SET(BOOST_DIR "c:\\dev_32\\Boost" CACHE PATH "The Boost Directory Path")
SET(PROTOBUF_DIR "c:\\dev_32\\Protobuf" CACHE PATH "The Protobuf directory Path")
SET(OPENSSL_DIR "c:\\dev_32\\OpenSSL" CACHE PATH "The OpenSSL Directory Path")
SET(DEPLOY_DIR "c:\\root_32" CACHE PATH
"The Deploy Path for the components built" )
endif()
endif()