Trait ReadonlySupplier 

pub trait ReadonlySupplier<T> {
    // Required method
    fn get(&self) -> T;

    // Provided methods
    fn into_box(self) -> BoxReadonlySupplier<T>
       where Self: Sized + 'static,
             T: 'static { ... }
    fn into_rc(self) -> RcReadonlySupplier<T>
       where Self: Sized + 'static,
             T: 'static { ... }
    fn into_arc(self) -> ArcReadonlySupplier<T>
       where Self: Sized + Send + Sync + 'static,
             T: Send + 'static { ... }
    fn into_fn(self) -> impl FnMut() -> T
       where Self: Sized { ... }
    fn to_box(&self) -> BoxReadonlySupplier<T>
       where Self: Clone + 'static,
             T: 'static { ... }
    fn to_rc(&self) -> RcReadonlySupplier<T>
       where Self: Clone + 'static,
             T: 'static { ... }
    fn to_arc(&self) -> ArcReadonlySupplier<T>
       where Self: Clone + Send + Sync + 'static,
             T: Send + 'static { ... }
    fn to_fn(&self) -> impl FnMut() -> T
       where Self: Clone { ... }
}

Read-only supplier trait: generates values without modifying state.

The core abstraction for stateless value generation. Unlike Supplier<T>, it uses &self instead of &mut self, enabling usage in read-only contexts and lock-free concurrent access.

Key Characteristics

• No input parameters: Pure value generation
• Read-only access: Uses &self, doesn’t modify state
• Returns ownership: Returns T (not &T) to avoid lifetime issues
• Lock-free concurrency: Arc implementation doesn’t need Mutex

Automatically Implemented for Closures

All Fn() -> T closures automatically implement this trait, enabling seamless integration with both raw closures and wrapped supplier types.

Examples

Using with Generic Functions

use prism3_function::{ReadonlySupplier, BoxReadonlySupplier};

fn call_twice<S: ReadonlySupplier<i32>>(supplier: &S)
    -> (i32, i32)
{
    (supplier.get(), supplier.get())
}

let s = BoxReadonlySupplier::new(|| 42);
assert_eq!(call_twice(&s), (42, 42));

let closure = || 100;
assert_eq!(call_twice(&closure), (100, 100));

Stateless Factory

use prism3_function::ReadonlySupplier;

struct User {
    name: String,
}

impl User {
    fn new() -> Self {
        User {
            name: String::from("Default"),
        }
    }
}

let factory = || User::new();
let user1 = factory.get();
let user2 = factory.get();
// Each call creates a new User instance

Author

Haixing Hu

Required Methods

fn get(&self) -> T

Generates and returns a value.

Executes the underlying function and returns the generated value. Uses &self because the supplier doesn’t modify its own state.

Returns

The generated value of type T

Examples

use prism3_function::{ReadonlySupplier, BoxReadonlySupplier};

let supplier = BoxReadonlySupplier::new(|| 42);
assert_eq!(supplier.get(), 42);
assert_eq!(supplier.get(), 42);

Provided Methods

fn into_box(self) -> BoxReadonlySupplier<T>

where Self: Sized + 'static, T: 'static,

Converts to BoxReadonlySupplier.

This method has a default implementation that wraps the supplier in a BoxReadonlySupplier. Custom implementations can override this method for optimization purposes.

Returns

A new BoxReadonlySupplier<T> instance

Examples

use prism3_function::ReadonlySupplier;

let closure = || 42;
let boxed = closure.into_box();
assert_eq!(boxed.get(), 42);

fn into_rc(self) -> RcReadonlySupplier<T>

where Self: Sized + 'static, T: 'static,

Converts to RcReadonlySupplier.

This method has a default implementation that wraps the supplier in an RcReadonlySupplier. Custom implementations can override this method for optimization purposes.

Returns

A new RcReadonlySupplier<T> instance

Examples

use prism3_function::ReadonlySupplier;

let closure = || 42;
let rc = closure.into_rc();
assert_eq!(rc.get(), 42);

fn into_arc(self) -> ArcReadonlySupplier<T>

where Self: Sized + Send + Sync + 'static, T: Send + 'static,

Converts to ArcReadonlySupplier.

This method has a default implementation that wraps the supplier in an ArcReadonlySupplier. Custom implementations can override this method for optimization purposes.

Returns

A new ArcReadonlySupplier<T> instance

Examples

use prism3_function::ReadonlySupplier;

let closure = || 42;
let arc = closure.into_arc();
assert_eq!(arc.get(), 42);

fn into_fn(self) -> impl FnMut() -> T

where Self: Sized,

Converts to a closure implementing FnMut() -> T.

This method has a default implementation that wraps the supplier in a closure. Custom implementations can override this method for optimization purposes.

Returns

A closure implementing FnMut() -> T

Examples

use prism3_function::ReadonlySupplier;

let closure = || 42;
let mut fn_mut = closure.into_fn();
assert_eq!(fn_mut(), 42);
assert_eq!(fn_mut(), 42);

fn to_box(&self) -> BoxReadonlySupplier<T>

where Self: Clone + 'static, T: 'static,

Converts to BoxReadonlySupplier by cloning.

This method clones the supplier and wraps it in a BoxReadonlySupplier. Requires Self: Clone. Custom implementations can override this method for optimization.

Returns

A new BoxReadonlySupplier<T> instance

Examples

use prism3_function::ReadonlySupplier;

let closure = || 42;
let boxed = closure.to_box();
assert_eq!(boxed.get(), 42);

fn to_rc(&self) -> RcReadonlySupplier<T>

where Self: Clone + 'static, T: 'static,

Converts to RcReadonlySupplier by cloning.

This method clones the supplier and wraps it in an RcReadonlySupplier. Requires Self: Clone. Custom implementations can override this method for optimization.

Returns

A new RcReadonlySupplier<T> instance

Examples

use prism3_function::ReadonlySupplier;

let closure = || 42;
let rc = closure.to_rc();
assert_eq!(rc.get(), 42);

fn to_arc(&self) -> ArcReadonlySupplier<T>

where Self: Clone + Send + Sync + 'static, T: Send + 'static,

Converts to ArcReadonlySupplier by cloning.

This method clones the supplier and wraps it in an ArcReadonlySupplier. Requires Self: Clone + Send + Sync. Custom implementations can override this method for optimization.

Returns

A new ArcReadonlySupplier<T> instance

Examples

use prism3_function::ReadonlySupplier;

let closure = || 42;
let arc = closure.to_arc();
assert_eq!(arc.get(), 42);

fn to_fn(&self) -> impl FnMut() -> T

where Self: Clone,

Converts to a closure by cloning.

This method clones the supplier and wraps it in a closure implementing FnMut() -> T. Requires Self: Clone. Custom implementations can override this method for optimization.

Returns

A closure implementing FnMut() -> T

Examples

use prism3_function::ReadonlySupplier;

let closure = || 42;
let mut fn_mut = closure.to_fn();
assert_eq!(fn_mut(), 42);
assert_eq!(fn_mut(), 42);

Implementors

impl<T> ReadonlySupplier<T> for ArcReadonlySupplier<T>

impl<T> ReadonlySupplier<T> for BoxReadonlySupplier<T>

impl<T> ReadonlySupplier<T> for RcReadonlySupplier<T>

impl<T, F> ReadonlySupplier<T> for F

where F: Fn() -> T,