I've started a branch (export_module), but adding a post here describing the high-level strategy stuff for feedback.

Basically, the Export modules live in the space of "similar enough that there's a lot of duplication, dissimilar enough that it's often hard to figure out why in Spreadsheets you get X but in Databases you get Y". This is not a great situation.

We've been talking about doing a merge and cleanup for at least as long as I've been in the group, so let's make CP5 the version where we get it done.

Vision:

• Deprecate EtD and EtS
• Create new "ExportData" module
  • The actual-actual work of writing to X output format will get extracted out to new exporter/format.py files per format, probably in the utilities directory - this keeps things semi-organized, and makes it easy to add or deprecate individual formats as we like.
  • The ExportData module handles all the settings choices about what we're saving and where
    • Unless actually technically IMPOSSIBLE to implement for a particular backend, most options now become generic across output formats. No more "you can pick your measurements when writing to a spreadsheet but not a database" or "you can have a checkbox export the Object relationships info in a database but not in a spreadsheet"
• CPA Properties/Workspace stuff go to new "CreateCellProfilerAnalystFiles" module
• We will try as we're doing this to resolve/address the 20+ open issues for the Export modules

Anticipated challenges:

• Probably at least some of the things that are output-format-specific are so for a reason. We'll find out which as we go, presumably.
• Upgrade path - this is going to be definitely not-trivial in terms of upgrading existing pipelines with regards to both merging data exports AND handling properties file creation if it already existed
• We will probably want to institute some sort of checker that when CreateCellProfilerAnalystFiles is in the pipeline, that it has ExportData and with a compatible format - unclear to me without digging into the internals more if this is birds or national parks