Deferred

Rust crate to help perform deferred execution of code logic.

Idea

This crate can be used specifically for operations where you need to execute different parts of logic at unspecified time but you cannot use futures or any other asynchronous operations.

Usage

Record in Cargo.toml:

[dependencies]
deferred = "1.1"

Your crate module:

#[macro_use]
extern crate deferred;

use deferred::*;

fn foo(v: i32) -> Deferred<i32> {
    deferred!(v, [
        |c| state!(c.state() + 1),
        |c| foo2(c.state()).into(),
        |c| state!(c.state() + 2)
    ])
}

fn foo2(v: i32) -> Deferred<i32> {
    deferred!(v, [
      |c| state!(c.state() * 2),
      |c| state!(c.state() * 3)
    ])
}

{
  let d = foo(1);
  assert!(d.can_resume());
  assert_eq!(d.state(), Some(&1));

  let d = d.resume().unwrap();
  assert!(d.can_resume());
  assert_eq!(d.state(), Some(&2));

  let d = d.resume().unwrap();
  assert!(d.can_resume());
  assert_eq!(d.state(), Some(&4));

  let d = d.resume().unwrap();
  assert!(d.can_resume());
  assert_eq!(d.state(), Some(&12));

  let d = d.resume().unwrap();
  assert!(!d.can_resume());
  assert_eq!(d.state(), Some(&14));
}
// IS EQUIVALENT TO:
{
  let d = foo(1);
  assert_eq!(d.consume(), 14);
}