From 512712e28a0f1cd0b554a060b89bf351121c5da9 Mon Sep 17 00:00:00 2001
From: Marcus Stollsteimer <sto.mar@web.de>
Date: Sun, 5 Nov 2023 18:36:33 +0100
Subject: [PATCH] Add `grss` implementation to errors chapter

At the end of the chapter, provide a running code example
that applies the nicer error reporting to the `grrs` tool.
---
 Cargo.toml                  |  4 ++++
 src/tutorial/errors-impl.rs | 26 ++++++++++++++++++++++++++
 src/tutorial/errors.md      |  9 +++++++++
 3 files changed, 39 insertions(+)
 create mode 100644 src/tutorial/errors-impl.rs

diff --git a/Cargo.toml b/Cargo.toml
index dd480a8..5d0a9e4 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -28,6 +28,10 @@ path = "src/tutorial/errors-custom.rs"
 name = "errors-exit"
 path = "src/tutorial/errors-exit.rs"
 
+[[bin]]
+name = "errors-impl"
+path = "src/tutorial/errors-impl.rs"
+
 [[bin]]
 name = "output-progressbar"
 path = "src/tutorial/output-progressbar.rs"
diff --git a/src/tutorial/errors-impl.rs b/src/tutorial/errors-impl.rs
new file mode 100644
index 0000000..e9954b6
--- /dev/null
+++ b/src/tutorial/errors-impl.rs
@@ -0,0 +1,26 @@
+use anyhow::{Context, Result};
+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() -> Result<()> {
+    let args = Cli::parse();
+
+    let content = std::fs::read_to_string(&args.path)
+        .with_context(|| format!("could not read file `{}`", args.path.display()))?;
+
+    for line in content.lines() {
+        if line.contains(&args.pattern) {
+            println!("{}", line);
+        }
+    }
+
+    Ok(())
+}
diff --git a/src/tutorial/errors.md b/src/tutorial/errors.md
index 6992615..84cf0da 100644
--- a/src/tutorial/errors.md
+++ b/src/tutorial/errors.md
@@ -233,3 +233,12 @@ Error: could not read file `test.txt`
 Caused by:
     No such file or directory (os error 2)
 ```
+
+## Wrapping up
+
+The complete code for our `grrs` tool with improved error reporting
+will look like this:
+
+```rust,ignore
+{{#include errors-impl.rs}}
+```