Example of using copy and "generator" with CMake-files

CMakeLists.txt

cmake_minimum_required(VERSION 3.11)
project(LearningCMake)

set(Hmm "${CMAKE_CURRENT_BINARY_DIR}/hmm.cpp")
set(Foo "${CMAKE_CURRENT_BINARY_DIR}/foo.cpp")
set(Bar "${CMAKE_CURRENT_BINARY_DIR}/bar.cpp")

add_executable(LearningCMake ${Hmm} "${Foo}" "${Bar}")

add_custom_command(OUTPUT ${Hmm}
        COMMAND cp hmm.xml ${Hmm}
        WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
        DEPENDS hmm.xml)

configure_file(foo.txt "${Foo}" COPYONLY)
configure_file(bar.txt "${Bar}" COPYONLY)