Crate retained

retained

Documentation

Keep local variables between repeated function calls using simple macro.

This crate is no_std.

Usage

use retained::retained;

#[retained(DrawState)]
fn draw() {
    #[retained]
    let ref mut check_box: CheckBox = CheckBox::new(/* checked */ false);
    check_box.draw();
}

fn draw_loop() {
    let mut state = DrawState::new();

    loop {
        draw(&mut state);
    }
}

Without retained, Checkbox’s states would be reset on every draw call. By using retained, local variable check_box is kept inside DrawState struct. And draw function gets additional &mut DrawState argument.

Examples

See examples for simple example and egui demo ported using retained.

License

This crate is licensed under MIT OR Apache-2.0

Attribute Macros

retained

Create external storage for tagged local variables and bind to original let statement.