Struct App 

pub struct App { /* private fields */ }

Main application struct that manages the game loop and plugin lifecycle

The App coordinates:

• Plugin registration and initialization
• System scheduling (startup and per-frame)
• Main loop execution
• Resource cleanup on shutdown

Example

use kon::prelude::*;

fn main() {
    Kon::new()
        .add_plugin(DefaultPlugins)
        .add_startup_system(setup)
        .add_system(update)
        .run();

Implementations

impl App

pub fn new() -> App

Creates a new App instance

Initializes logging and installs custom panic handler

pub fn add_plugin<P>(&mut self, plugin: P) -> &mut App

where P: Plugin,

Adds a plugin to the application

Plugins extend engine functionality. Common examples:

• EcsPlugin - Registers the World
• WindowPlugin - Creates the game window
• DefaultPlugins - Bundle of core plugins

Returns

Self reference for method chaining

pub fn add_startup_system<F>(&mut self, system: F) -> &mut App

where F: FnMut(&mut Context) + 'static,

Adds a startup system that runs once at application start

Returns

Self reference for method chaining

pub fn add_system<F>(&mut self, system: F) -> &mut App

where F: FnMut(&mut Context) + 'static,

Adds a system that runs every frame

Returns

Self reference for method chaining

pub fn register<R>(&mut self, resource: R) -> &mut App

where R: Any + Send + Sync + 'static,

Registers a global resource accessible from all systems

Resources are stored in Context and accessible via ctx.global::<T>().

Returns

Self reference for method chaining

pub fn context(&self) -> &Context

Returns an immutable reference to the engine context

pub fn context_mut(&mut self) -> &mut Context

Returns a mutable reference to the engine context

pub fn run(&mut self)

Runs the application main loop

Lifecycle

1. Initialize all plugins (call ready())
2. Execute startup systems once
3. Run main loop until ctx.quit() is called:
   • Update frame timing
   • Execute all systems in order
   • Clear events (prevents stale data next frame)
4. Cleanup plugins on exit

Trait Implementations

impl Default for App

fn default() -> App

Returns the “default value” for a type.