That is fair. From an users perspective, I can imagine thinking "I already said config.doFringe=False. Why do I also have to say getFringeData=False?" I'm thinking that your initial commit that passed the whole ccdExposure may be better than getFringeData without a default (especially if it makes your edits to the obs_ packages cleaner). I guess it comes down to the lesser of two evils: require the users to pass an exposure just to get some data from the butler or ask the users to decide whether to read in the fringe data.

Hopefully, New Butler will allow us to write a def checkFilters(self, sensorRef). Seems like it should be possible if the butler can already find the flats/fringes of the correct filter based only on the dataId.

Alright, branch u/hfc-3/DM-4266 in ip_isr and tickets/DM-4266 in obs_lsstSim have the latest corrections. No other obs_* packages call readIsrData.

The current solution is that the raw exposure is passed to readIsrData, and there is no default. Hopefully the comment of the argument is clear that it won't encourage misuse.

For now FringeTask.readFringes still returns a Struct including fringes, I am still thinking to refactor so that it returns fringes only, probably in a future ticket. It was discussed a little bit in HipChat (Nov 12, Science Pipelines room) and my notes from there:

• It is very important to be entirely deterministic
• The seed should be different for every exposure (fringe exposure?)
• Would be even better if the fringe regions and fringe measurements are persisted

OK to merge after it passes Jenkins or buildbot test. Remember that the builds don't run all the obs_ packages, so check by hand that obs_cfht unit tests pass.

Unrelated note: I see lots of draft branches for this ticket. The project encourages rebasing if you're working alone on a branch. I know I'll edit my commits many many times between creating the branch and merging.

Passed Jenkins: https://ci.lsst.codes/job/stack-os-matrix/label=centos-6/5672//console

Tests of obs_lsstSim and ip_isr are included in the Jenkins build.
Also ran and passed obs_cfht and obs_decam tests manually. Do not have the correct testdata_subaru to run obs_subaru tests.

Changes are merged to master.

 python/lsst/obs/lsstSim/lsstSimIsrTask.py | 2 +-

 tests/testLsstSimIsrTask.py               | 2 +-

 2 files changed, 2 insertions(+), 2 deletions(-)

 python/lsst/ip/isr/isrTask.py | 24 +++++++++++++++---------

 1 file changed, 15 insertions(+), 9 deletions(-)