What's New in 1.0

1.0 is the first stable release. The API introduced in 0.10 is now covered by Semantic Versioning: no breaking changes until 2.0, and anything removed is deprecated for at least one minor release first.

Coming from 0.9.x? Start with Upgrading from 0.9.x. For the current release, see What's New in 1.1.

Replacing a dependency across the graph

Scope.provide() makes one instance stand in for a dependency everywhere in the graph — the supported way to use test doubles:

service = UserService()
scope_of(service).provide(Database, FakeDatabase())

async with service:
    assert service.repository.database is service.database     # both the fake

The provided unit runs its own hooks and enters the dependencies its own class declares.

Assigning to a dependency attribute now raises AttributeError pointing to provide(). In 0.10 it silently replaced that one attribute while the rest of the graph, and the lifecycle, kept the original.

Starting again

stop() undoes start, so the same graph can start again. @init is not rerun:

async with service:     # init, start, stop
    ...
async with service:     # start, stop
    ...

In 0.10 the second start() returned without running anything.

Retrying a failure

A failed or cancelled advance no longer leaves a record, so calling it again runs it again. In 0.10 every later call re-raised the first exception. Relatedly, start() after a failed init() now raises LifecycleError instead of proceeding.

Upgrading from 0.10

0.10	1.0
service.database = FakeDatabase()	scope_of(service).provide(Database, FakeDatabase()) before the lifecycle begins
for unit in scope.entered["start"]	for unit in scope.entered["start"].values() — keyed by type
Build a new root to restart	Call start() again on the same root