1 unstable release
0.1.0 | Sep 12, 2024 |
---|
#9 in #fn
7KB
80 lines
dyn-fn-once
Dynamically-typed self-consuming closures in Rust.
lib.rs
:
Provides dynamically-typed self-consuming closures, [DynFnOnce] and [DynFnOnceSend].
E.g.
use std::fmt::Write;
use dyn_fn_once::DynFnOnce;
/// Creates a closure which either multiplies or adds two numbers, and stores the result
/// in `target`, returning the given string with the result appended.
fn create_binary_operation<'capture>(
target: &'capture mut u32,
mut units: String,
mul: bool
) -> DynFnOnce<'capture, (u32, u32), String> {
if mul {
let statically_typed_closure = move |a, b| {
let product = a * b;
units.write_fmt(format_args!(" = {product}")).unwrap();
*target = product;
units
};
// N.B. the closure takes multiple arguments, so we have to turn them
// into a single tuple-typed argument
DynFnOnce::from(|(a, b)| statically_typed_closure(a, b))
} else {
let statically_typed_closure = move |a, b| {
let sum = a + b;
units.write_fmt(format_args!(" = {sum}")).unwrap();
*target = sum;
units
};
// N.B. the closure takes multiple arguments, so we have to turn them
// into a single tuple-typed argument
DynFnOnce::from(|(a, b)| statically_typed_closure(a, b))
}
}
let mut target: u32 = 0;
assert_eq!(
create_binary_operation(&mut target, String::from("Hertz"), true).call((3, 4)),
String::from("Hertz = 12")
);
assert_eq!(target, 12);
assert_eq!(
create_binary_operation(&mut target, String::from("Watts"), false).call((3, 4)),
String::from("Watts = 7")
);
assert_eq!(target, 7);