Module supplier_once 

SupplierOnce Types

Provides one-time supplier implementations that generate and return values without taking any input parameters, consuming themselves in the process.

Overview

A SupplierOnce is a functional abstraction similar to Supplier, but can only be called once. The get() method consumes self, ensuring the supplier cannot be reused.

Key Characteristics

• Single use: Can only call get() once
• Consumes self: The method takes ownership of self
• Holds FnOnce: Can capture and move non-cloneable values
• Type-system guaranteed: Prevents multiple calls at compile time

Use Cases

1. Lazy initialization: Delay expensive computation until needed
2. One-time resource consumption: Generate value by consuming a resource
3. Move-only closures: Hold closures that capture moved values

Examples

Lazy Initialization

use prism3_function::{BoxSupplierOnce, SupplierOnce};

let once = BoxSupplierOnce::new(|| {
    println!("Expensive initialization");
    42
});

let value = once.get(); // Only initializes once
assert_eq!(value, 42);

Moving Captured Values

use prism3_function::{BoxSupplierOnce, SupplierOnce};

let resource = String::from("data");
let once = BoxSupplierOnce::new(move || resource);

let value = once.get();
assert_eq!(value, "data");

Author

Haixing Hu

Structs

BoxSupplierOnce

Box-based one-time supplier.

Traits

SupplierOnce

One-time supplier trait: generates a value consuming self.