Started Rust in Action MEAP.

1 files changed, 55 insertions, 0 deletions

diff --git a/meap/meap-code/ch3/ch3-not-quite-file-3.rs b/meap/meap-code/ch3/ch3-not-quite-file-3.rs
new file mode 100644
index 0000000..a88d112
--- /dev/null
+++ b/meap/meap-code/ch3/ch3-not-quite-file-3.rs
@@ -0,0 +1,55 @@
+#![allow(unused_variables)]

+

+#[derive(Debug)]

+struct File {

+  name: String,

+  data: Vec<u8>,

+}

+

+impl File {

+  fn new(name: &str) -> File {

+    File {                     

+      name: String::from(name),  

+      data: Vec::new(),        

+    }

+  }

+

+  fn new_with_data(name: &str, data: &Vec<u8>) -> File { // <1> This method has snuck in to deal with cases where we want to simulate cases where a file has pre-existing data

+    let mut f = File::new(name);

+    f.data = data.clone();

+    f

+  }

+

+  fn read(self: &File, save_to: &mut Vec<u8>) -> usize { // <2> The `f` argument has been replaced with `self` 

+    let mut tmp = self.data.clone();

+    let read_length = tmp.len();

+    save_to.reserve(read_length);

+    save_to.append(&mut tmp);

+    read_length

+  }

+}

+

+fn open(f: &mut File) -> bool { // <3> These two can remain as-in until we've looked at error handling 

+  true 

+}

+

+fn close(f: &mut File) -> bool { // <3>

+  true

+}

+

+fn main() {

+  let f3_data: Vec<u8> = vec![114, 117, 115, 116, 33]; // <4> An explicit type needs to be provided, as `vec!` can't infer the necessary type through the function boundary

+  let mut f3 = File::new_with_data("2.txt", &f3_data); 

+

+  let mut buffer: Vec<u8> = vec![];

+

+  open(&mut f3);

+  let f3_length = f3.read(&mut buffer); // <5> Here is the the change in the calling code 

+  close(&mut f3);

+  

+  let text = String::from_utf8_lossy(&buffer);

+

+  println!("{:?}", f3);

+  println!("{} is {} bytes long", &f3.name, f3_length);

+  println!("{}", text);

+}
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