Draft for now, since I want to discuss the approach a bit (I have two).

Basically, this changes it so that we use a clear function for each DType rather than the current "specialized" PyArray_Decref, which cannot be extended to non-objects.

We already have functions to clear buffers internally in the casting machinery, so this wires them in. There are two very unrelated questions:

• Should we even bother keeping PyArray_Decref() in case someone wants to decref without also clearing? I would still prefer deprecating it, I think. But maybe we should first expose the new API... Unless we can just rename the symbol.

• I have two different approaches to do this:

  1. This one uses the ArrayMethod which is very simple because it fits with our casting setup. But we don't need resolve_dtypes and need to pass a lot of indirections (there is 1 array to operate, so we only need 1 stride, data pointer, etc.)
  2. We could create a new specialized function. This requires duplicating a bit of the casting setup (for support of structured dtypes) and means a bit more new API. OTOH, such API might be useful for re-use for a TRAVERSE slot, which I presume we need eventually.
     (For some Python implementations, I believe you must have a traverse).