On 10/1/2018 1:07 PM, Robert Ramey via Boost wrote:
Background ==========
My personal knowledge of build systems is somewhat limited.
a) I don't really understand CMake all that well. I have made CMakeLists.txt files for both the serialization library and the safe numerics libraries as an aid to build and maintain IDE and make files used in running tests and posting results to CDash.
b) I don't really understand our current system, Boost Build, very well either. I've made jam files for building and running tests for the serialization and safe numerics libraries.
c) I recently reviewed C++Now 2017: Daniel Pfeifer's excellent video from C++Now 2017 “Effective CMake" - https://www.youtube.com/watch?v=bsXLMQ6WgIk . I recommend it highly.
Despite my lack of knowledge in this area, or perhaps because of it, I've volunteered to direct the effort to evolve Boost so that users of Boost can avail themselves of the benefits of CMake. This effort will be organized as follows:
a) A discussion on the boost developers mailing list with the goal of reaching a consensus as to what benefits CMake can and should provide to users and developers of Boost. This effort will commence with the posting of this notice. I hope that this discussion can be more or less resolved within 30 days.
b) I will then synthesize from the above discussion a call for proposals which lists the requirements and requirements.
c) Those proposing CMake for boost will have approximately 90 days to prepare their proposals. Their proposal are expected to look similar to a boost library proposal. That is they are expected to have some (CMake) code, along with tests, documentation including tutorials and reference. This is only an expectation. It's conceivable that such a proposal might only contain conventions and and samples of what boost library should contain to fulfill the requirements. As with boost libraries, submissions are not required to totally complete. But they have to be sufficiently complete to convince reviewers the the submission fulfills the stated requirements and can be finished in good time.
d) After the 90 day period, submissions will be reviewed simultaneously. Note that this is at a variance from normal boost procedure of reviewing submissions one at a time. Since we expect to receive a number of submissions and only one can be accepted, the normal boost protocol can't really function. Target date for this review is 1 February 2019.
e) After the review period the review manager will prepare a report which includes the decision of which submission will be accepted into the official boost distribution. Currently, I, Robert Ramey, expect to be review manager. However, it's possible that this by the time the review is undertaken, this coveted position could be assigned to some more worthy candidate.
Scope, Requirements and Features ================================
We presume that submissions will fulfill the applicable requirements of any boost submission. In addition we would like to see the following addressed.
Library Build ------------- “Effective CMake" - https://www.youtube.com/watch?v=bsXLMQ6WgIk Recommends that all libraries - including header only libraries have a CMakeList.txt file. What should this include for Boost Libraries?
Library Test ------------ Should facilities for "testing" be only done by developers? or should users who acquire library packages also be able to test libraries. Should CMake testing results posting be used - CDASH? Should we just skip the issue of Library Testing and continue to depend on Boost Build.
Library Packaging ----------------- Is the library packaging facility provide by CMake - CPACK - useful to boost. Should boost libraries be updated to support it?
Dependencies ------------ If the above is implemented, can we depend upon CMake to handle library dependencies? Or does some special functionality Do circular dependencies constitute a problem?
Modularity ---------- Currently boost is organized as a tightly integrated group of libraries. This organization manifests itself in a number of ways. We have a Boost "super project" in github. Boost libraries are "sub projects" of this super project. This known structure is exploited by and depended upon by boost tools. Should CMake support continue this policy/design. We distribute boost as "super project". Should we continue to do this or distribute libraries on a library by library basis. Does CMake/CPACK etc. make this "simple"?
Documentation/testing --------------------- What support should be require for uses of Boost CMake implementation. Documentation, examples, templates for helping library developers. How should the CMake design/implementation be tested?
Other considerations -------------------- add your requirement/features here.
Useful Resources =============== “Effective CMake" - https://www.youtube.com/watch?v=bsXLMQ6WgIk https://gist.github.com/mbinna/c61dbb39bca0e4fb7d1f73b0d66a4fd1 https://github.com/purpleKarrot/Boost.CMake https://www.youtube.com/watch?v=eC9-iRN2b04
Please try to keep this discussion on this list.
I know that there has been a lot going on on slack. But having it in two places makes it harder for me to review and summarize. Also slack doesn't conveniently maintain comment hierarchy. So please try to keep this discussion on this list.
I strongly suggest that the goal of using CMake with Boost begin with making Boost libraries, whether header-only or built, available to CMake projects. This also means that we have a way of testing whether or not such a solution actually works for any given Boost library. My own preference for testing whether or not such a solution would work or not would be to use our current b2/Boost Build test jamfiles, but if this is too difficult to do we still need some way to test the solution for each library so each library maintainer can see whether or not the solution we choose works for his library. This should be our first goal and all other goals should be tabled until and when we can have a solution where this works flawlessly and there is a general agreement that whatever proposal is chosen to implement this is best. Only when the above is fully accomplished should Boost then look into the goal of using CMake internally, perhaps for test, docs, building libraries, or what-not. We need to work this way because every solution is bound to end with comments that it does X but does not do Y or it does X and Y but does not do Z, and we all know where these endless arguments end: that we end up doing nothing because we start by trying to do too much and we can never reach agreement.
Robert Ramey