Rust, catch_unwind

Method catch_unwind can be used to handle unwinding panics.

When panic happened , program will terminate.

fn main() {
    panic!("hello");
    println!("world")
}   

Code above , will never reach println! macro. So it will not print world.

We can use catch_unwind method to catch panic and handle it and not terminate program.

use std::panic::catch_unwind;

fn main() {
    let result = catch_unwind(|| {
        panic!("hello")
    });
    match result {
        Ok(_) => println!("no panic!"),
        Err(e) => println!("panic with error: {:?}", e)
    }
    println!("world")
}   

catch_unwind method take a closure as argument, in this closure body, let’s call panic macro to make it panic. catch_unwind method return a result, so we store it to a variable result.

Let’s use match expression to handle that result. First arm’s pattern is Ok, we just print “no panic”. Second arm’s pattern is cause of panic , and let’s print that in the Err.

Last we call println “world”

When we run this code , it will print : hello , then cause of panic ,then world.