How to migrate from 0.16¶

Release 0.17 moves to bluesky 1.16, which renames the method a device uses to report new readings, and builds sessions out of a registry on diwire instead of an in-n-out store. This page gives the changes your code may need. The changelog lists everything else the release changed.

An axis reports readings through subscribe_reading¶

The positioner follows an Axis by calling its subscribe_reading method, the name bluesky 1.16 gives it, instead of subscribe. An axis built on ophyd-async, such as a StandardMovable or a signal, has both methods and needs no change. An axis you wrote by hand with only subscribe is no longer an Axis, so the positioner leaves it out. Rename the method:

# 0.16
class MyAxis(StandardReadable):
    def subscribe(self, function: Callback[float]) -> None:
        self.position.subscribe_reading(function)


# now
class MyAxis(StandardReadable):
    def subscribe_reading(self, function: Callback[float]) -> None:
        self.position.subscribe_reading(function)

A frontend overrides make_registry¶

A session now builds its components out of a Registry, and the method a frontend overrides to share it with an application of its own returns one. Rename the method and return the registry the session makes:

# 0.16
class MyFrontend(Session):
    def make_store(self) -> Store:
        return self.app.injection_store


# now
class MyFrontend(Session):
    def make_registry(self) -> Registry:
        registry = super().make_registry()
        self.app.registry = registry
        return registry

in-n-out comes with the Qt extras¶

redsun no longer installs in-n-out on its own. The pyqt and pyside extras still bring it, because app-model needs it. Code that imports in_n_out in a session without either extra adds it to its own dependencies:

uv add in-n-out

One value per type¶

A type the session holds a value for can be shared by one owner only. A component that shares a value under a type the session already provides, such as SessionConfig, or under the class of a component declared once, now stops the build with RegistrationError, which names both owners. Share the value under a type of the component's own:

# 0.16
class MyController:
    @provides
    def config(self) -> SessionConfig: ...


# now
MyConfig = NewType("MyConfig", SessionConfig)


class MyController:
    @provides
    def config(self) -> MyConfig: ...

A parameter asks for the exact type¶

A component receives a value only under the type it was registered with. A parameter typed with a subclass of a shared type, or with a union A | B, no longer receives the value of the base class or of one member, so a required parameter like that stops the build with "which nothing in the session provides". Ask for the type the value is shared under. A union with a default, such as A | B | None = None, keeps its default.

# 0.16: received the Stage shared by another component
class MyView:
    def setup(self, stage: MyStage) -> None: ...


# now
class MyView:
    def setup(self, stage: Stage) -> None: ...