Handle errors

3 files changed, 110 insertions, 0 deletions

diff --git a/errors/.gitignore b/errors/.gitignore
new file mode 100644
index 0000000..e629269
--- /dev/null
+++ b/errors/.gitignore
@@ -0,0 +1,18 @@
+
+# Created by https://www.toptal.com/developers/gitignore/api/rust
+# Edit at https://www.toptal.com/developers/gitignore?templates=rust
+
+### Rust ###
+# Generated by Cargo
+# will have compiled files and executables
+/target/
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here https://doc.rust-lang.org/cargo/guide/cargo-toml-vs-cargo-lock.html
+Cargo.lock
+
+# These are backup files generated by rustfmt
+**/*.rs.bk
+
+# End of https://www.toptal.com/developers/gitignore/api/rust
+
diff --git a/errors/Cargo.toml b/errors/Cargo.toml
new file mode 100644
index 0000000..b7a199b
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+++ b/errors/Cargo.toml
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+[package]
+name = "errors"
+version = "0.1.0"
+authors = ["Jordan Gong <jordan.gong@protonmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
diff --git a/errors/src/main.rs b/errors/src/main.rs
new file mode 100644
index 0000000..e98e987
--- /dev/null
+++ b/errors/src/main.rs
@@ -0,0 +1,83 @@
+use std::fs::File;
+use std::io::ErrorKind;
+
+fn main() {
+    // panic!("crash and burn");
+
+    // let f = File::open("hello.txt");
+
+    // let f = match f {
+    //     Ok(file) => file,
+    //     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 file: {:?}", other_error)
+    //         }
+    //     },
+    // };
+
+    // Rustacean style
+    // let f = File::open("hello.txt").unwrap_or_else(|error| {
+    //     if error.kind() == ErrorKind::NotFound {
+    //         File::create("hello.txt").unwrap_or_else(|error| {
+    //             panic!("Problem creating the file: {:?}", error);
+    //         })
+    //     } else {
+    //         panic!("Problem opening file: {:?}", error);
+    //     }
+    // });
+
+    // Shortcut
+    // let f = File::open("hello.txt").unwrap();
+
+    // let f = File::open("hello.txt").expect("Failed to open hello.txt");
+
+    // Propagating
+    use std::io;
+    use std::io::Read;
+
+    // fn read_username_from_file() -> Result<String, io::Error> {
+    //     let f = File::open("hello.txt");
+
+    //     let mut f = match f {
+    //         Ok(file) => file,
+    //         Err(e) => return Err(e),
+    //     };
+
+    //     let mut s = String::new();
+
+    //     match f.read_to_string(&mut s) {
+    //         Ok(_) => Ok(s),
+    //         Err(e) => Err(e),
+    //     }
+    // }
+
+    // Propagating shortcut
+    // fn read_username_from_file() -> Result<String, io::Error> {
+    //     let mut f = File::open("hello.txt")?;
+    //     let mut s = String::new();
+    //     f.read_to_string(&mut s)?;
+    //     Ok(s)
+    // }
+
+    // Chaining
+    // fn read_username_from_file() -> Result<String, io::Error> {
+    //     let mut s = String::new();
+
+    //     File::open("hello.txt")?.read_to_string(&mut s)?;
+
+    //     Ok(s)
+    // }
+
+    // Using `fs::read_to_string`
+    use std::fs;
+    fn read_username_from_file() -> Result<String, io::Error> {
+        fs::read_to_string("hello.txt")
+    }
+
+    let r = read_username_from_file();
+    println!("{:?}", r);
+}