Parameters

The container can also hold configuration parameters to configure services. This feature allows self-contained service declarations by adding @service and annotations to indicate what to inject.

Warning

Parameters are for application configuration only. They should not be used to pass values around or as a global session object.

Use parameters for app configuration like environment name, database URL, mailer URL, etc.

Inject by name

To inject a parameter by name, annotate the type with Inject(param="param_name").

@service
class GithubClient:
    def __init__(self, api_key: Annotated[str, Inject(param="gh_api_key")]) -> None:
        ...

Parameter expressions

You can interpolate parameters using a special syntax to retrieve and concatenate multiple parameter values.

Note: The result is a string, so non-string parameters will be converted using str().

def target(logs_dir: Annotated[str, Inject(expr="${cache_dir}/${env}/logs")]) -> None:
    ...

🏭 Class-based configuration

Wireup's parameter configuration is optional. You can use typed classes for configuration, supported via factories.

Register your settings as a service and inject them into factories like regular dependencies.

See Use Without Annotations for more info.