def test_ownership_diagram(self):
info = Info()
system = DeleteListenerSystem(info.record_deletion)
builder = DiagramBuilder()
# `system` is now owned by `builder`.
builder.AddSystem(system)
# `system` is now owned by `diagram`.
diagram = builder.Build()
# Delete the builder. Should still be alive.
del builder
self.assertFalse(info.deleted)
# Delete the diagram. Should be dead.
del diagram
# Using `py::keep_alive`, `system` will keep `builder` alive after
# `.AddSystem` is called, and `builder` will keep `diagram` alive after
# `.Build` is called.
# Transitively, `system` will keep `builder` alive (as its old owner)
# and `diagram` (as its new owner, which is kept alive by `builder`).
self.assertFalse(info.deleted)
self.assertTrue(system is not None)
del system
# Upon removing this reference, everything should have been cleared up.
# However, since we work around #14355 by inducing a keep_alive cycle,
# it will not be deleted.
self.assertFalse(info.deleted)
def test_ownership_multiple_containers(self):
info = Info()
system = DeleteListenerSystem(info.record_deletion)
builder_1 = DiagramBuilder()
builder_2 = DiagramBuilder()
builder_1.AddSystem(system)
# This is tested in our fork of `pybind11`, but echoed here for when
# we decide to switch to use `shared_ptr`.
with self.assertRaises(RuntimeError):
# This should throw an error from `pybind11`, since two containers
# are trying to own a unique_ptr-held object.
builder_2.AddSystem(system)
def test_ownership_simulator(self):
info = Info()
system = DeleteListenerSystem(info.record_deletion)
simulator = Simulator(system)
self.assertFalse(info.deleted)
del simulator
# Simulator does not own the system.
self.assertFalse(info.deleted)
self.assertTrue(system is not None)
# Now ensure that having a system be alive will keep
# the system alive (using `py::keep_alive`).
simulator = Simulator(system)
del system
self.assertFalse(info.deleted)
del simulator
self.assertTrue(info.deleted)
def test_basic(self):
info = Info()
system = DeleteListenerSystem(info.record_deletion)
self.assertFalse(info.deleted)
del system
self.assertTrue(info.deleted)
