Misunderstanding Jump from 1.4->1.5+

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!");
}

Read the linked tutorial chapters 1.3, 1.4, and 1.5, comparing how main.rs and the command-line example evolve between them. Determine the intended progression and update the tutorial so the later output, logging, and progress-bar material connects coherently to the earlier application; the chapters should form a clear continuous guide when done.