Panic Hooks
Demonstrates the setting up panic hooks
git clone https://github.com/ratatui-org/ratatui.git --branch latestcd ratatuicargo run --example=panic --features=crossterm
//! # [Ratatui] Panic Hook example//!//! The latest version of this example is available in the [examples] folder in the repository.//!//! Please note that the examples are designed to be run against the `main` branch of the Github//! repository. This means that you may not be able to compile with the latest release version on//! crates.io, or the one that you have installed locally.//!//! See the [examples readme] for more information on finding examples that match the version of the//! library you are using.//!//! [Ratatui]: https://github.com/ratatui-org/ratatui//! [examples]: https://github.com/ratatui-org/ratatui/blob/main/examples//! [examples readme]: https://github.com/ratatui-org/ratatui/blob/main/examples/README.md
//! How to use a panic hook to reset the terminal before printing the panic to//! the terminal.//!//! When exiting normally or when handling `Result::Err`, we can reset the//! terminal manually at the end of `main` just before we print the error.//!//! Because a panic interrupts the normal control flow, manually resetting the//! terminal at the end of `main` won't do us any good. Instead, we need to//! make sure to set up a panic hook that first resets the terminal before//! handling the panic. This both reuses the standard panic hook to ensure a//! consistent panic handling UX and properly resets the terminal to not//! distort the output.//!//! That's why this example is set up to show both situations, with and without//! the chained panic hook, to see the difference.
use std::{error::Error, io};
use ratatui::{ crossterm::{ event::{self, Event, KeyCode}, execute, terminal::{disable_raw_mode, enable_raw_mode, EnterAlternateScreen, LeaveAlternateScreen}, }, prelude::*, widgets::{Block, Paragraph},};
type Result<T> = std::result::Result<T, Box<dyn Error>>;
#[derive(Default)]struct App { hook_enabled: bool,}
impl App { fn chain_hook(&mut self) { let original_hook = std::panic::take_hook();
std::panic::set_hook(Box::new(move |panic| { reset_terminal().unwrap(); original_hook(panic); }));
self.hook_enabled = true; }}
fn main() -> Result<()> { let mut terminal = init_terminal()?;
let mut app = App::default(); let res = run_tui(&mut terminal, &mut app);
reset_terminal()?;
if let Err(err) = res { println!("{err:?}"); }
Ok(())}
/// Initializes the terminal.fn init_terminal() -> Result<Terminal<CrosstermBackend<io::Stdout>>> { execute!(io::stdout(), EnterAlternateScreen)?; enable_raw_mode()?;
let backend = CrosstermBackend::new(io::stdout());
let mut terminal = Terminal::new(backend)?; terminal.hide_cursor()?;
Ok(terminal)}
/// Resets the terminal.fn reset_terminal() -> Result<()> { disable_raw_mode()?; execute!(io::stdout(), LeaveAlternateScreen)?;
Ok(())}
/// Runs the TUI loop.fn run_tui<B: Backend>(terminal: &mut Terminal<B>, app: &mut App) -> io::Result<()> { loop { terminal.draw(|f| ui(f, app))?;
if let Event::Key(key) = event::read()? { match key.code { KeyCode::Char('p') => { panic!("intentional demo panic"); }
KeyCode::Char('e') => { app.chain_hook(); }
_ => { return Ok(()); } } } }}
/// Render the TUI.fn ui(f: &mut Frame, app: &App) { let text = vec![ if app.hook_enabled { Line::from("HOOK IS CURRENTLY **ENABLED**") } else { Line::from("HOOK IS CURRENTLY **DISABLED**") }, Line::from(""), Line::from("press `p` to panic"), Line::from("press `e` to enable the terminal-resetting panic hook"), Line::from("press any other key to quit without panic"), Line::from(""), Line::from("when you panic without the chained hook,"), Line::from("you will likely have to reset your terminal afterwards"), Line::from("with the `reset` command"), Line::from(""), Line::from("with the chained panic hook enabled,"), Line::from("you should see the panic report as you would without ratatui"), Line::from(""), Line::from("try first without the panic handler to see the difference"), ];
let paragraph = Paragraph::new(text) .block(Block::bordered().title("Panic Handler Demo")) .centered();
f.render_widget(paragraph, f.size());}