Struct sai::System

pub struct System<T> where
    T: ComponentRegistry,  {
    pub entrypoint: Option<TypeId>,
    // some fields omitted
}

A system is a collection of components + the ability to control the lifecycle of components in a way meeting the dependency requirement of components, e.g. start/stop them.

// Assume a RootRegistry is defined here
use sai::{System, Component, component_registry};

#[derive(Component)]
struct Foo {
}

component_registry!(RootRegistry, [Foo]);

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut system : System<RootRegistry> = System::new();
    println!("System starting up...");
    system.start().await;
    println!("System started.");

    // Waiting for Ctrl-c
    // signal::ctrl_c().await?;

    println!("System shutting down...");
    system.stop().await;
    println!("System shutted down.");
    Ok(())
}

Fields

entrypoint: Option<TypeId>

If this is set, then the system will only start components that can be reached by this entrypoint.

Implementations

impl<T> System<T> where
    T: ComponentRegistry, 

pub fn new() -> Self

Create a new system with a Component Registry

Example

use sai::{component_registry, System};
component_registry!(RootRegistry, [ component1, component2 ]);

let system: System<RootRegistry> = System::new();

pub fn with_entrypoint(entrypoint: TypeId) -> Self

Similar to System::new() but allow you to specified an entrypoint for the system. If an entrypoint is specified, it will become the topology root of component tree.

pub async fn start(&mut self)

Create & start all components in the registry in a topological order. The topological order is automatically derived by system from analysing #[injected] macro attributes in component definitons.

The entrypoints will be automatically detected unless specifically specified.

following the example above:

system.start().await;

pub async fn stop(&mut self)

Stop and drop all components in a topological order in reverse to startup. A typical example used with tokio signal:

use tokio::signal;

...

// Waiting for Ctrl-c
signal::ctrl_c().await?;
println!("System shutting down...");
system.stop().await;
println!("System shutted down.");