ch8: add misc error examples

ch8/misc/io-error.rs

@@ -0,0 +1,7 @@
+use std::fs::File;
+
+fn main() -> Result<(), std::io::Error> {
+    let _f = File::open("invisible.txt")?;
+
+    Ok(())
+}

ch8/misc/mac-addresses.rs

@@ -0,0 +1,43 @@
+use std::fmt;
+use std::fmt::Display;
+
+#[derive(Debug)]
+struct MacAddress([u8; 6]);
+
+impl Display for MacAddress {
+  fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+    let octet = self.0;
+    write!(
+      f,
+      "{:02x}:{:02x}:{:02x}:{:02x}:{:02x}:{:02x}",
+      octet[0], octet[1], octet[2], octet[3], octet[4], octet[5]
+    )
+  }
+}
+
+impl MacAddress {
+  fn is_local(&self) -> bool {
+    (self.0[0] & 0b_0000_0010) == 0
+  }
+
+  fn is_universal(&self) -> bool {
+    !self.is_local()
+  }
+
+  fn is_unicast(&self) -> bool {
+    (self.0[0] & 0b_0000_0001) == 0
+  }
+
+  fn is_multicast(&self) -> bool {
+    !self.is_unicast()
+  }
+}
+
+fn main() -> Result<(), std::io::Error> {
+  let mac = MacAddress([0x6, 0, 0, 0, 0, 0]);
+  println!("mac: {}", mac);
+  println!("mac: {:?}", mac);
+  println!("universal?: {:?}", mac.is_universal());
+
+  Ok(())
+}

ch8/misc/multierror.rs

@@ -0,0 +1,11 @@
+use std::fs::File;
+use std::net::Ipv6Addr;
+
+fn main() -> Result<(), std::io::Error> {
+  let _f = File::open("invisible.txt")?;
+
+  let _localhost = "::1"
+    .parse::<Ipv6Addr>()?;
+
+  Ok(())
+}

ch8/misc/traiterror.rs

@@ -0,0 +1,10 @@
+use std::fs::File;
+use std::error::Error;
+use std::net::Ipv6Addr;
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let _f = File::open("invisible.txt")?;
+    let _localhost = "::1".parse::<Ipv6Addr>()?;
+
+    Ok(())
+}

ch8/misc/wraperror.rs

@@ -0,0 +1,24 @@
+use std::io;
+use std::fmt;
+use std::net;
+use std::fs::File;
+use std::net::Ipv6Addr;
+
+#[derive(Debug)]
+enum UpstreamError{
+  IO(io::Error),
+  Parsing(net::AddrParseError),
+}
+
+impl fmt::Display for UpstreamError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:?}", self) // <1> Implement Display in terms of Debug
+    }
+}
+
+fn main() -> Result<(), UpstreamError> {
+    let _f = File::open("invisible.txt").map_err(UpstreamError::IO)?;
+    let _localhost = "::1".parse::<Ipv6Addr>().map_err(UpstreamError::Parsing)?;
+
+    Ok(())
+}

ch8/misc/wraperror2.rs

@@ -0,0 +1,36 @@
+use std::io;
+use std::fmt;
+use std::net;
+use std::fs::File;
+use std::net::Ipv6Addr;
+
+#[derive(Debug)]
+enum UpstreamError{
+  IO(io::Error),
+  Parsing(net::AddrParseError),
+}
+
+impl fmt::Display for UpstreamError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{:?}", self) // <1> Implement Display in terms of Debug
+    }
+}
+
+impl From<io::Error> for UpstreamError {
+    fn from(error: io::Error) -> Self {
+        UpstreamError::IO(error)
+    }
+}
+
+impl From<net::AddrParseError> for UpstreamError {
+    fn from(error: net::AddrParseError) -> Self {
+        UpstreamError::Parsing(error)
+    }
+}
+
+fn main() -> Result<(), UpstreamError> {
+    let _f = File::open("invisible.txt").map_err(UpstreamError::IO)?;
+    let _localhost = "::1".parse::<Ipv6Addr>().map_err(UpstreamError::Parsing)?;
+
+    Ok(())
+}