wrapping up

Cargo.lock

@@ -52,6 +52,12 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "anyhow"
+version = "1.0.97"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dcfed56ad506cb2c684a14971b8861fdc3baaaae314b9e5f9bb532cbe3ba7a4f"
+
 [[package]]
 name = "clap"
 version = "4.5.35"
@@ -102,6 +108,7 @@ checksum = "5b63caa9aa9397e2d9480a9b13673856c78d8ac123288526c37d7839f2a86990"
 name = "grrs"
 version = "0.1.0"
 dependencies = [
+ "anyhow",
  "clap",
 ]
 

Cargo.toml

@@ -4,4 +4,5 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
+anyhow = "1.0"
 clap = { version = "4.0", features = ["derive"] }

src/main.rs

@@ -1,3 +1,4 @@
+use anyhow::{Context, Result};
 use clap::Parser;
 
 #[derive(Parser)]
@@ -6,13 +7,17 @@ struct Cli {
     path: std::path::PathBuf,
 }
 
-#[derive(Debug)]
-struct CustomError(String);
+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);
+        }
+    }
 
-fn main() -> Result<(), CustomError> {
-    let path = "test.txt";
-    let content = std::fs::read_to_string(path)
-        .map_err(|err| CustomError(format!("Error reading `{}`: {}", path, err)))?;
-    println!("file content: {}", content);
     Ok(())
 }