Callables returned from a callable to be tracked

[mofojed]

For some methods, such as ui.table.context_menu, we want to provide menu action items from a callable. Meaning we need a way to notify the client of these callables, and then have the client call back when they're out of scope so they are cleaned up properly.

e.g. With a context menu call:

def _on_context_menu(cell_index: CellIndex, row_data: RowData) -> ContextMenuAction:
  # This method `print_hello_world` is getting returned to the client as a result of the call to get menu items when the context menu is triggered on the client
  def print_hello_world():
    print("Hello World")

  return ContextMenuAction(title="Hello World", action=print_hello_world)

# The method `_on_context_menu` gets called when the context menu is triggered on the client
ui_table.context_menu(items=_on_context_menu)

So it should work for the context_menu, but be done in a generic way such that any callable that returns other objects/callables as part of the result, should retain those objects/callables until the client has instructed they can be deleted/cleaned up.

[mattrunyon]

I think we could use a FinalizationRegistry on the JS side here if we don't care about the cleanup always being immediate. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/FinalizationRegistry

Basically a cleanup function when any registered object is garbage collected. We could also add a util to explicitly cleanup and remove the object from the FinalizationRegistry.