Struct App 

pub struct App { /* private fields */ }

A world and the headless loop that runs it.

run drives the world until a system stops it or its last system finishes; run_for is the bounded form, for a test or a tool that wants a known number of ticks. Both start the world if the caller has not.

In dev builds the loop holds itself to a steady state of no allocation per tick, which is asserted rather than assumed. See run.

Implementations

impl App

pub fn from_world(world: World) -> Self

An app that runs world with no systems over it: what a caller gets when the host contributes no system table.

pub fn with_systems(world: World, table: &'static SystemTable) -> Self

An app that runs world under table, which is what gives it systems.

pub fn world(&self) -> &World

Borrow the world being run.

pub fn ticks(&self) -> u64

Ticks stepped so far.

pub fn start(&mut self) -> Result<(), CnResult>

Build the world’s systems and run their init. Runs once: a second call is InvalidState rather than a second init over the running world.

pub fn run(&mut self) -> Result<StepResult, CnResult>

Step until a system stops the world or the last one finishes, returning which of the two ended the run.

Under debug_assertions the loop asserts its own steady state: past a warmup, a settled world’s tick allocates nothing, and a stretch of ticks that all allocate is a cost that would recur every frame for the life of the app, so the run panics naming the tick that allocated least. The counters behind that are process-wide, so the check stands down where it cannot trust them: where no binary installed the tracking allocator, and where another thread is allocating alongside the loop.

pub fn run_for(&mut self, ticks: u64) -> Result<StepResult, CnResult>

Step at most ticks times, returning what the last tick reported: Continue when the full count ran, Stop or Done when the world ended the run early. The bounded form of run.

Trait Implementations

impl Debug for App

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.