Nate Lust The revised code on meas_base is better, thanks. There are still a couple of issues which I think need attention: you should eliminate the duplicate `typedefs` and take another crack at the comment in the `fail()` function.

Beyond that, there are a lot of minor spacing and formatting issues. I feel almost bad about pulling you up on these trivial issues, but they do need fixing. I wonder if there are linters that could help you track down these issues in C++ code automatically – might be worth investigating. (There are certainly code formatters, like clang-format, but you want something that'll point out mistakes rather than attempt to reformat the whole file.)

By the way, I'm assuming DM-4201 was a response to my request for a tech debt tickets covering this work? It's a start, but could you make it much more explicit about what actually needs doing, please.

Nate Lust Three tiny whitespace tweaks on your latest meas_base iteration – almost perfect. I suggest you just take care of them when squashing history. I am happy for you to merge, but equally willing to take a look at your cleaned up history first if you like.

This work has been completed and merged to master in: meas_base, pipe_tasks, and obs_subaru.

Thanks Nate Lust. As a final step, could you please write a brief (no more than a couple of sentences) summary of the new functionality you have enabled in the LSST stack and add it to https://confluence.lsstcorp.org/display/DM/Data+Release+Production+WIP+W16+release+notes ? Thanks!