No boost

[davidsummers]

This addresses the first part of issue #1287 by removing the boost formatting and program_options dependencies.

This is just a quick hack. I'm sure there are better ways to do it but this works.

Please review and let me know if other ways to do it are required to have this accepted into the range-v3 project.

[davidsummers]

This is still a work in progress.

I've accomplished part 1 of Issue #1287 and I'm working on trying to replace the BOOT date with the date library date::sys_days.

If anyone has any ideas on how to do that I would really appreciate knowing how to accomplish the second goal.

So far I've tried two approaches and neither one work. (See the issue for the details).

[davidsummers]

With the last commit, I now have a working calendar example program without the requirement for BOOST.

Please consider merging this into the master branch and what changes to this code would be required to accomplish that.

This was just a quick hack and I'm sure there are probably better ways to do it but this works.

[davidsummers]

How do I figure out how to fix the failed checks?

I think at one point everything showed as working.

I assume changes since then now cause the checks to fail?

How to fix?

[ericniebler]

I don't want to drop a full date/time library into the examples/ directory. I would love to see this example use @HowardHinnant's date library, or standard facilities when available. I'm not sure what the options are for downloading it and/or taking a dependency on it.

I would be perfectly OK with dropping the dependency on a library for command line argument parsing.

[JohelEGP]

CMake's file(DOWNLOAD) can do the job here.

[ericniebler]

I have also had success with ExternalProject_Add (include(ExternalProject)) before.

[JohelEGP]

FetchContent would be preferable to ExternalProject, but it was added in CMake 3.11. Since only a header is needed, file(DOWNLOAD) is saner than the dance needed to please ExternalProject usage.