src/error/abort_unwind.md

# `abort` and `unwind`

The previous section illustrates the error handling mechanism `panic`.  Different code paths can be conditionally compiled based on the panic setting. The current values available are `unwind` and `abort`.

Building on the prior lemonade example, we explicitly use the panic strategy to exercise different lines of code.

```rust,editable,mdbook-runnable
fn drink(beverage: &str) {
    // You shouldn't drink too much sugary beverages.
    if beverage == "lemonade" {
        if cfg!(panic = "abort") {
            println!("This is not your party. Run!!!!");
        } else {
            println!("Spit it out!!!!");
        }
    } else {
        println!("Some refreshing {} is all I need.", beverage);
    }
}

fn main() {
    drink("water");
    drink("lemonade");
}
```

Here is another example focusing on rewriting `drink()` and explicitly use the `unwind` keyword.

```rust,editable
#[cfg(panic = "unwind")]
fn ah() {
    println!("Spit it out!!!!");
}

#[cfg(not(panic = "unwind"))]
fn ah() {
    println!("This is not your party. Run!!!!");
}

fn drink(beverage: &str) {
    if beverage == "lemonade" {
        ah();
    } else {
        println!("Some refreshing {} is all I need.", beverage);
    }
}

fn main() {
    drink("water");
    drink("lemonade");
}
```

The panic strategy can be set from the command line by using `abort` or `unwind`.

```console
rustc  lemonade.rs -C panic=abort
```