The idea is automatic coercion of arguments through gi exposed methods could support plugable from-python methods. This would allow the removal of explicit coercion in overrides that look like this:

    def get_cell_area(self, path, column=None):
        if not isinstance(path, Gtk.TreePath):
            path = TreePath(path)
        return super(TreeView, self).get_cell_area(path, column)


I propose a simple API using a decorator which could be something like the following:


class TreeIter(Gtk.TreeIter):
    @gi.register_coerce_from(tuple)
    @classmethod
    def from_tuple(cls, value):
        return ...

TreePath = override(TreePath)


An added benefit here is we also get an explicit "from_tuple" class method which can work as you would expect and can replace complex initializers with type checking in certain cases.
How this works internally can be left as an implementation detail but the proposed API should already provide enough information to make this happen.