Make TopologySeafloorGrid the class, and SeafloorGrid its deprecated alias

[jcannon-gplates]

TopologySeafloorGrid (added in 129f018, the commit that created grids/) subclassed SeafloorGrid only to give it a generate() named like IsochronSeafloorGrid's. So grids/oceans.py was the topology gridder under another name, and topology_seafloor_grid.py held a single forwarding method.

• TopologySeafloorGrid is now the class. The implementation moves from grids/oceans.py into grids/topology_seafloor_grid.py, with generate() included and unchanged. grids/oceans.py is deleted.
• There is no shared base class. The two gridders share no code, and their generate() methods take different arguments, so a base class would only document a coincidence. Each has its own generate().
• SeafloorGrid has been public since GPlately 1.x, so it stays as a deprecated alias. It is the same class as TopologySeafloorGrid, so isinstance checks work with either name. A module-level __getattr__ (PEP 562) raises the DeprecationWarning whenever the name is looked up, including when unpickling an object pickled under the old name. It isn't in __all__, so from gplately import * doesn't warn. Its old module paths still work, both as imports and as attributes:
  • from gplately.oceans import SeafloorGrid;
  • from gplately.grids.oceans import SeafloorGrid, which 2.1.0rc0 had.
• The netCDF metadata_source attribute stays "GPlately.SeafloorGrid", so output files are unchanged.
• Updated to TopologySeafloorGrid: the CLI, the tests, the docs (use_cases.rst, examples.rst), Notebooks/README.md and CLAUDE.md. api.rst drops gplately.SeafloorGrid, whose page would only duplicate TopologySeafloorGrid's. The 2.1.0 release notes gain a bullet covering both gridders.

Interaction with #413: #413 modifies grids/oceans.py. The merge base also has a topology_seafloor_grid.py, so git sees a delete and a rewrite here rather than a rename. Merging this into #413 will therefore be a modify/delete conflict on oceans.py, to be resolved by porting #413's changes into the renamed file. I'll do that when I next merge master into #413.

Testing

On Windows, Python 3.13:

• tests-dir/pytestcases: 246 passed and 12 skipped. The skips are the raster tests that the default test level leaves out.
• A new test checks that SeafloorGrid is TopologySeafloorGrid, warns on every lookup (directly, by import, and through both old module paths, as imports and as attributes), and that the current name doesn't warn.
• Also checked by hand: isinstance holds both ways, inspect.signature(SeafloorGrid) shows the real parameters, and pickles naming gplately.oceans.SeafloorGrid or gplately.grids.oceans.SeafloorGrid load as TopologySeafloorGrid.
• The Sphinx docs, built from scratch for master and this branch: no warnings in either. The TopologySeafloorGrid page now renders the class docstring's links and three images; they were Markdown, left over from the pdoc docs, and rendered as literal text. The use_cases.rst example also had two lines indented one space too far, which made it fail with IndentationError when copied. That's fixed, and it calls generate().
• The CLI config topology-seafloor-gridding-1.toml, run through this branch, wrote all 18 grids, the same as before.

🤖 Generated with Claude Code

https://claude.ai/code/session_012j73LisSSEedpvtr4odRCG

[jcannon-gplates]

Hi @michaelchin, this reworks part of the grids/ layout from 129f018: TopologySeafloorGrid becomes the class itself (moved from oceans.py), rather than a SeafloorGrid subclass that adds generate(). SeafloorGrid stays as a deprecated alias, so existing code keeps working. Could you check it fits what you intended for the two gridders? (There's no shared base class, since they share no code.)

If you're happy then I'll merge it.

Note: Michael approved this via email (2nd Oct).