Passing the argument to CMAKE via command prompt

Question

I have a makefile for my project and also I am passing some argument and based on that argument i am seting some flag. I am able to do this . but now I want to do the same using cmake. I have created cmakelist.txt but I don't know how to pass the argument and check for the argument value in cmakelist.txt.

Sample of my makefile:

ifeq "$(FAB)" "po"       //setting some flags else       //setting some iother flag endif 

What is the way to take the argument from command prompt and set flags based on that?

Answer 1

In the CMakeLists.txt file, create a cache variable, as documented here:

SET(FAB "po" CACHE STRING "Some user-specified option") 

Source: http://cmake.org/cmake/help/v2.8.8/cmake.html#command:set

Then, either use the GUI (ccmake or cmake-gui) to set the cache variable, or specify the value of the variable on the cmake command line:

cmake -DFAB:STRING=po 

Source: http://cmake.org/cmake/help/v2.8.8/cmake.html#opt:-Dvar:typevalue

Modify your cache variable to a boolean if, in fact, your option is boolean.

Answer 2

CMake 3.13 on Ubuntu 16.04

This approach is more flexible because it doesn't constraint MY_VARIABLE to a type:

$ cat CMakeLists.txt  message("MY_VARIABLE=${MY_VARIABLE}") if( MY_VARIABLE )      message("MY_VARIABLE evaluates to True") endif()  $ mkdir build && cd build  $ cmake .. MY_VARIABLE= -- Configuring done -- Generating done -- Build files have been written to: /path/to/build  $ cmake .. -DMY_VARIABLE=True MY_VARIABLE=True MY_VARIABLE evaluates to True -- Configuring done -- Generating done -- Build files have been written to: /path/to/build  $ cmake .. -DMY_VARIABLE=False MY_VARIABLE=False -- Configuring done -- Generating done -- Build files have been written to: /path/to/build  $ cmake .. -DMY_VARIABLE=1 MY_VARIABLE=1 MY_VARIABLE evaluates to True -- Configuring done -- Generating done -- Build files have been written to: /path/to/build  $ cmake .. -DMY_VARIABLE=0 MY_VARIABLE=0 -- Configuring done -- Generating done -- Build files have been written to: /path/to/build