feat: error propagation shortcut

Signed-off-by: Fredrik Klingenberg <[email protected]>

projects/panic/src/main.rs

@@ -1,9 +1,28 @@
 use std::fs::File;
+use std::io::{self, ErrorKind};
+use std::io::Read;
 
 fn main() {
     let greeting_file_result = File::open("hello.txt");
     let _greeting_file = match greeting_file_result {
         Ok(file) => file,
-        Err(error) => panic!("Problem opening the file: {:?}", error),
+        Err(error) => match error.kind() {
+            ErrorKind::NotFound => match File::create("hello.txt") {
+                Ok(fc) => fc,
+                Err(e) => {
+                    panic!("Problem creating the file: {:?}", e)
+                },
+            },
+            other_error => {
+                panic!("Problem opening the file: {:?}", other_error)
+            }
+        },
     };
 }
+
+fn read_username_from_file() -> Result<String, io::Error> {
+    let mut username_file = File::open("hello.txt")?;
+    let mut username = String::new();
+    username_file.read_to_string(&mut username)?;
+    Ok(username)
+}