Misunderstanding Jump from 1.4->1.5+

[Muddledde]

First, thank you for taking the time to create this guide (and reading this). :-)

It was my understanding from the beginning that the guide would guide one towards creating a simple Command Line App, but after 1.4 there doesn't appear to be much cohesion. I assume I am missing something here, but 1.5 (and further) changes main.rs in a way that it doesn't appear to function around the same logic built/defined before 1.4.

1.3

#![allow(unused)]

use clap::Parser;

/// Search for a pattern in a file and display the lines that contain it.
#[derive(Parser)]
struct Cli {
    /// The pattern to look for
    pattern: String,
    /// The path to the file to read
    path: std::path::PathBuf,
}

fn main() {
    let args = Cli::parse();
    let content = std::fs::read_to_string(&args.path).expect("could not read file");

    for line in content.lines() {
        if line.contains(&args.pattern) {
            println!("{}", line);
        }
    }
}

1.4

use anyhow::{Context, Result};

fn main() -> Result<()> {
    let path = "test.txt";
    let content = std::fs::read_to_string(path)
        .with_context(|| format!("could not read file `{}`", path))?;
    println!("file content: {}", content);
    Ok(())
}

1.5 gives an example of a bunch of nice tools to add (such as logging and progress bars), but as mentioned earlier, there is no cohesion with the early development; no addition to the previously constructed chapters.

Printer Performance

#![allow(unused)]
fn main() {
use std::io::{self, Write};

let stdout = io::stdout(); // get the global stdout entity
let mut handle = stdout.lock(); // acquire a lock on it
writeln!(handle, "foo: {}", 42); // add `?` if you care about errors here
}

Progress Bar

fn main() {
    let pb = indicatif::ProgressBar::new(100);
    for i in 0..100 {
        do_hard_work();
        pb.println(format!("[+] finished #{}", i));
        pb.inc(1);
    }
    pb.finish_with_message("done");
}

Logging

use log::{info, warn};

fn main() {
    env_logger::init();
    info!("starting up");
    warn!("oops, nothing implemented!");
}

[epage]

Good call.

We also should be highlighting that prinln will panic on broken pipes

[axjms1]

Just came here to chime in and agree with @Muddledde. I love the idea of this shorter intro to cli programs, but it does seem to need a bit of updating. How can I help?

[stomar]

A smaller "jump already happens with 1.4, the error handling code is not really integrated into the earlier grss example. Rather, the example used in the error chapter is essentially independent from the code developed earlier (admittedly with some similarities).

[stomar]

An implementation of grss with improved error handling has been added at the end of chapter 1.4 (#233), but still the code is not developed incrementally into the given form.