Enumerate console parameters (argv) in CMake

Question

I want to parse/process passed console parameters in CMake, so that if I run this in console:

cmake -DCMAKE_BUILD_TYPE=Release -DSOME_FLAG=1 ..

I want to obtain the -DCMAKE_BUILD_TYPE=Release and -DSOME_FLAG=1 from this inside CMake script (and every other parameter passed) and save them somewhere.

The reason I want it is to pass all parameters through custom CMake script (which calls execute_process(cmake <something>) after) e.g.

cmake -DCMAKE_BUILD_TYPE=Release -P myscript.cmake

Answer 1

There is CMAKE_ARGC variable which contains amount of variables passed to CMake (divided by whitespaces), and CMAKE_ARGV0, CMAKE_ARGV1, ... which contains actual values.

It's common for languages for C++ that first (zero) variable holds the command you called (cmake in this situation), so we will need everything except CMAKE_ARGV0. Let's make a simple loop then:

set(PASSED_PARAMETERS "") # it will contain all params string
set(ARG_NUM 1) # current index, starting with 1 (0 ignored)

# you can subtract something from that if you want to ignore some last variables
# using "${CMAKE_ARGC}-1" for example 
math(EXPR ARGC_COUNT "${CMAKE_ARGC}") 

while(ARG_NUM LESS ARGC_COUNT)
    # making current arg named "CMAKE_ARGV" + "CURRENT_INDEX"
    # in CMake like in Bash it's easy
    set(CURRENT_ARG ${CMAKE_ARGV${ARG_NUM}}) 

    message(STATUS "Doing whatever with ${CURRENT_ARG}")  

    # adding current param to the list
    set(PASSED_PARAMETERS ${PASSED_PARAMETERS} ${CURRENT_ARG})        

    math(EXPR ARG_NUM "${ARG_NUM}+1") # incrementing current index
endwhile()

(Answering my own question, didn't find anything like that in SO, maybe it'll help someone)