CustomFunction

The CustomFunction trait is an optional trait for supporting user-level custom functions. Through the CustomFunction trait, you can retrieve custom functions stored in the storage system. You can choose to implement the CustomFunction trait alone or together with the CustomFunctionMut trait.

In some cases, you might want to provide storage-specific functions pre-built and separately available for each storage system. In such cases, you can implement the CustomFunction trait and create additional functions stored in advance when using it. To achieve this, the CustomFunction and CustomFunctionMut traits are provided separately for implementation.

There are two methods available:

1. fetch_function: This method retrieves a custom function from the storage system using the provided function name.

2. fetch_all_functions: This method retrieves all custom functions stored in the storage system.

#[async_trait(?Send)]
pub trait CustomFunction {
    async fn fetch_function(&self, _func_name: &str) -> Result<Option<&StructCustomFunction>>;

    async fn fetch_all_functions(&self) -> Result<Vec<&StructCustomFunction>>;
}