Hi all,
thanks to you all for your replies!
Concluding from your replies, it seems that the following approach for
each external dependency implements a good(?) solution:
find_package(JPEG) # without "REQUIRED"
if (NOT JPEG_FOUND)
# Optionally, under Linux only:
# Stop with custom error message that explains how to install libjpeg.
# Or ask if alternatively the shipped library should be used.
# This complements the installation instructions in the user docs.
... # TODO!
# Proceed with the shipped copy of libjpeg:
# Always under Windows and possibly under Linux as outlined above.
# Always in source code form, compiling here; not pre-made binaries.
# (This approach is my personal preference over the other options
# that have been suggested.)
add_subdirectory(../ExtLibs/libjpeg ../ExtLibs/libjpeg)
... # see below
endif()
# How does this work in case `NOT JPEG_FOUND` above?
target_link_libraries(main_program ${JPEG_LIBRARIES})
That is, follow-up question: near the "..." above, we have got a target
"libjpeg", but how do I get the variables JPEG_INCLUDES, JPEG_LIBRARIES
etc. that `find_package(JPEG)` normally provides so that the last line
with the `target_link_libraries()` works?
I guess that defining them in `../ExtLibs/libjpeg/CMakeLists.txt` is wrong.
It seems to me that the 2017 talks by Mathieu Roperts and Daniel Pfeifer
(starting at slide 53, see especially slide 64 at
https://www.slideshare.net/DanielPfeifer1/effective-cmake) suggest that
this is how the modern, modular CMake is supposed to work?
Best regards,
Carsten
--
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
