prefect.utilities.dispatch

Provides methods for performing dynamic dispatch for actions on base type to one of its subtypes.

Example:

@register_base_type
class Base:
    @classmethod
    def __dispatch_key__(cls):
        return cls.__name__.lower()


class Foo(Base):
    ...

key = get_dispatch_key(Foo)  # 'foo'
lookup_type(Base, key) # Foo

Functions

get_registry_for_type ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/dispatch.py#L33" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

get_registry_for_type(cls: T) -> Optional[dict[str, T]]

Get the first matching registry for a class or any of its base classes.

If not found, None is returned.

get_dispatch_key ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/dispatch.py#L57" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

get_dispatch_key(cls_or_instance: Any, allow_missing: bool = False) -> Optional[str]

Retrieve the unique dispatch key for a class type or instance.

This key is defined at the __dispatch_key__ attribute. If it is a callable, it will be resolved.

If allow_missing is False, an exception will be raised if the attribute is not defined or the key is null. If True, None will be returned in these cases.

register_base_type ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/dispatch.py#L114" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

register_base_type(cls: T) -> T

Register a base type allowing child types to be registered for dispatch with register_type.

The base class may or may not define a __dispatch_key__ to allow lookups of the base type.

register_type ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/dispatch.py#L140" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

register_type(cls: T) -> T

Register a type for lookup with dispatch.

The type or one of its parents must define a unique __dispatch_key__.

One of the classes base types must be registered using register_base_type.

lookup_type ^{<a href="https://github.com/PrefectHQ/prefect/blob/main/src/prefect/utilities/dispatch.py#L197" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

lookup_type(cls: T, dispatch_key: str) -> T

Look up a dispatch key in the type registry for the given class.