RFC: restrict table._column_mixin to CPython's limited API - #18227

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@neutrinoceros - now that #18236 is merged, could you rebase and remove the exceptions for astropy/table? (and similarly for the WCS PR)

@astrofrog - I have no opinion on the code itself (defer to @mhvk on that), but can you some minimal profiling to confirm that performance is not impacted?

Benchmarks already ran successfully. Do you want something more fine grained ?

For the record, here are the benchmarks we are running:

https://github.com/astropy/astropy-benchmarks/blob/main/benchmarks/table.py

which benchmark(s) is/are the most relevant to look at here? (as @neutrinoceros you can see the results in the CI job for benchmarks)

I see the benchmarks ran. I downloaded the artifacts but the JSON files there are not immediately useful. Are there tools that help to analyze the data? Looking at the table tests, the closest test to getting a single item from a column is:

    def time_item_get_colfirst(self):
        self.table["b"][300]

However, this includes getting the column self.table["b"]. I guess that will be constant time, but still somewhat dilutes the impact of a change in the underlying getitem time.

In any case, I am satisified that the code does not impact item-get performance with this:

c = Column([1.5, 2.5])
%timeit c[1]

There was no appreciable difference between main and this branch, so all good!

rebased to refresh CI (some required jobs were not triggered).
It looks like we could merge this one as soon as it gets a formal approval ?

The Check PR change log job failed to get started. Not sure how to fix that.

There was some Ubuntu server hiccup too. I just rebased it so everything would rerun.

Is this good to merge if CI green? Thanks, all!

Benchmark failure unrelated (astropy/astropy-benchmarks#137) but also means we cannot test that in PR right now.

....time_large_gauss_combined_2d_SLSQPLSQFitter failed