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# dispatch
# `prefect.utilities.dispatch`
Provides methods for performing dynamic dispatch for actions on base type to one of its
subtypes.
Example:
```python theme={null}
@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`
```python theme={null}
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`
```python theme={null}
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`
```python theme={null}
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`
```python theme={null}
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`
```python theme={null}
lookup_type(cls: T, dispatch_key: str) -> T
```
Look up a dispatch key in the type registry for the given class.
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