Struct In

pub struct In<T>(pub T);

A SystemInput type which denotes that a System receives an input value of type T from its caller.

Systems may take an optional input which they require to be passed to them when they are being run. For FunctionSystems the input may be marked with this In type, but only the first param of a function may be tagged as an input. This also means a system can only have one or zero input parameters.

See SystemInput to learn more about system inputs in general.

Examples

Here is a simple example of a system that takes a usize and returns the square of it.

fn square(In(input): In<usize>) -> usize {
    input * input
}

let mut world = World::new();
let mut square_system = IntoSystem::into_system(square);
square_system.initialize(&mut world);

assert_eq!(square_system.run(12, &mut world).unwrap(), 144);

Tuple Fields

0: T

Trait Implementations

impl<T: Debug> Debug for In<T>

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

Formats the value using the given formatter.

impl<T> Deref for In<T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<T> DerefMut for In<T>

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<T: 'static> SystemInput for In<T>

type Param<'i> = In<T>

The wrapper input type that is defined as the first argument to FunctionSystems.

type Inner<'i> = T

The inner input type that is passed to functions that run systems, such as System::run.

fn wrap(this: Self::Inner<'_>) -> Self::Param<'_>

Converts a SystemInput::Inner into a SystemInput::Param.