The situation already involves a cache variable, though: `option(abc "cmt" ON)` is just syntactic sugar for `set(abc ON CACHE BOOL "cmt")`.
Petr On 20 May 2016 at 13:03, Jakob van Bethlehem <jsvanbethle...@gmail.com> wrote: > You don't have to create a cache variable for this. Put yourself in the > position of CMake; > * While scanning the CMakeLists.txt of Foo CMake encounters the set(OPT1 > ON FORCE) command, which tells CMake to create a *variable* called OPT1 > with value ON > * Then CMake is asked to include Bar > * While scanning Bar, CMake encounters the option() command, so it will > create an option called OPT1 > * end then.... nothing, CMake finished scanning > > Only the second time around, when CMake encounters the set(OPT1..) > command, it will have gained knowledge of the presence of the OPT1 option, > and hence it will realize it needs to change that option instead of > creating a variable with that name. > > So to me, your output is exactly as expected. I suspect if you include Bar > before setting the option, you will get the behaviour you expected. This, > to me, makes perfect sense, as Bar is a dependency of Foo, and hence needs > to be setup before you start setting up Foo. You wouldn't compile Foo > before compiling Bar, so why would that be different for the configuration > step. > > Sincerely, > Jakob > > On Fri, May 20, 2016 at 11:24 AM, Doug Cuthbertson < > doug.cuthbert...@gmail.com> wrote: > >> >> CMake (version 3.5.2) surprised me with how it's passing values to >> sub-projects, so I was wondering if this is expected behavior. Here's an >> example of what I mean. Let's say I have a project Foo in a directory of >> the same name. It contains a third-party library called Bar which has a >> CMakeLists.txt file that looks like: >> >> cmake_minimum_required(VERSION 2.8.12) >> >> option(OPT1 >> "Set to OFF|ON (default is OFF) to control build of Bar library" >> OFF) >> >> if(OPT1) >> message("Bar: OPT1 is on") >> else(OPT1) >> message("Bar: OPT1 is off") >> endif(OPT1) >> >> I then create CMakeLists.txt for Foo that sets OPT1 to ON and includes >> Bar: >> >> cmake_minimum_required(VERSION 2.8.12) >> >> set(OPT1 ON FORCE) >> if(OPT1) >> message("Foo: OPT1 is on") >> else(OPT1) >> message("Foo: OPT1 is off") >> endif(OPT1) >> add_subdirectory(Bar) >> >> The first time I run cmake the message output is: >> >> Foo: OPT1 is on >> Bar: OPT1 is off >> >> If I run cmake again, I get: >> >> Foo: OPT1 is on >> Bar: OPT1 is on >> >> If this is expected behavior, is there any way I can ensure Bar receives >> the value of OPT1 the first time? It makes a huge difference when the >> option controls, for example, whether a static or dynamic library will be >> built. >> >> Thanks, >> Doug >> >> -- >> >> Powered by www.kitware.com >> >> Please keep messages on-topic and check the CMake FAQ at: >> http://www.cmake.org/Wiki/CMake_FAQ >> >> Kitware offers various services to support the CMake community. For more >> information on each offering, please visit: >> >> CMake Support: http://cmake.org/cmake/help/support.html >> CMake Consulting: http://cmake.org/cmake/help/consulting.html >> CMake Training Courses: http://cmake.org/cmake/help/training.html >> >> Visit other Kitware open-source projects at >> http://www.kitware.com/opensource/opensource.html >> >> Follow this link to subscribe/unsubscribe: >> http://public.kitware.com/mailman/listinfo/cmake >> > > > -- > > Powered by www.kitware.com > > Please keep messages on-topic and check the CMake FAQ at: > http://www.cmake.org/Wiki/CMake_FAQ > > Kitware offers various services to support the CMake community. For more > information on each offering, please visit: > > CMake Support: http://cmake.org/cmake/help/support.html > CMake Consulting: http://cmake.org/cmake/help/consulting.html > CMake Training Courses: http://cmake.org/cmake/help/training.html > > Visit other Kitware open-source projects at > http://www.kitware.com/opensource/opensource.html > > Follow this link to subscribe/unsubscribe: > http://public.kitware.com/mailman/listinfo/cmake >
-- Powered by www.kitware.com Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Kitware offers various services to support the CMake community. For more information on each offering, please visit: CMake Support: http://cmake.org/cmake/help/support.html CMake Consulting: http://cmake.org/cmake/help/consulting.html CMake Training Courses: http://cmake.org/cmake/help/training.html Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Follow this link to subscribe/unsubscribe: http://public.kitware.com/mailman/listinfo/cmake