Crate defer_heavy

A versatile and easy to use defer statement for Rust. Similar to Go’s or Zig’s defer.

This crate is compatible uses no_std. The default features use alloc To disable alloc set default-features to false in cargo.toml.

This crates provides 6 macros for different use cases of deferment:

1. defer! simple deferment. Will execute when current scope ends.

2. defer_move! same as defer! but moves local variables into the closure.

3. defer_guard! Returns a guard that causes execution when its scope ends.

   • Execution can be canceled or preempted.

4. defer_move_guard! Same as defer_guard! but moves local variables into the closure.

5. defer_arc! Returns a reference counted guard than can be shared with other threads.

   • Execution can be canceled or preempted.
   • Closure must be Send
   • Target must support Arc & AtomicBool.
   • Target must support alloc
   • can be disabled with default-features=false in Cargo.toml

6. defer_move_arc! Same as defer_arc! but moves local variables into the closure.

   • All used local variables must be Send.

Usage

Add the dependency in your Cargo.toml:

[dependencies]
defer-heavy = "0.1.0"

Order of execution

Rust guarantees that the order in which the closures are dropped (and therefore executed) are in reverse order of creation. This means the last defer! in the scope executes first.

Macros

defer

Executes a block of code when the surrounding scope ends.

defer_arc

Executes a block of code when the surrounding scope ends.

defer_guard

Executes a block of code when the surrounding scope ends.

defer_move

Executes a block of code when the surrounding scope ends. This macro moves all captured variables.

defer_move_arc

Executes a block of code when the surrounding scope ends.

defer_move_guard

Executes a block of code when the surrounding scope ends.