Merge pull request #23 from shnmorimoto/2_4_3

added 2_4_3

Author: yuk1ty

chapter2/Cargo.toml

@@ -1,8 +1,8 @@
 [package]
-name = "chapter2"
-version = "0.1.0"
 authors = ["yytyd <[email protected]>"]
 edition = "2018"
+name = "chapter2"
+version = "0.1.0"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
@@ -16,6 +16,10 @@ path = "src/2_4_1/main.rs"
 name = "2_4_2"
 path = "src/2_4_2/main.rs"
 
+[[bin]]
+name = "2_4_3"
+path = "src/2_4_3/main.rs"
+
 [[bin]]
 name = "client_2_4_4"
 path = "src/2_4_4/client.rs"

chapter2/src/2_4_3/main.rs

@@ -0,0 +1,29 @@
+use std::io::Write;
+use std::str;
+
+#[derive(Debug)]
+enum BufferError {
+    IOError(std::io::Error),
+    StrError(str::Utf8Error),
+}
+
+impl From<std::io::Error> for BufferError {
+    fn from(error: std::io::Error) -> Self {
+        BufferError::IOError(error)
+    }
+}
+
+impl From<str::Utf8Error> for BufferError {
+    fn from(error: str::Utf8Error) -> Self {
+        BufferError::StrError(error)
+    }
+}
+
+fn main() -> Result<(), BufferError> {
+    let mut buffer: Vec<u8> = Vec::new();
+    buffer.write(b"bytes.Buffer example1\n")?;
+    println!("{}", str::from_utf8(&buffer)?);
+    buffer.write(b"bytes.Buffer example2\n")?;
+    println!("{}", str::from_utf8(&buffer)?);
+    Ok(())
+}