From 67cdcc2e12118becb823e20a40cc2687f2b8425a Mon Sep 17 00:00:00 2001
From: Adam Carpenter <53hornet@gmail.com>
Date: Wed, 27 Mar 2019 15:32:37 -0400
Subject: Started Rust in Action MEAP.

---
 meap/meap-code/ch3/ch3-not-quite-file-3.rs | 55 ++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 meap/meap-code/ch3/ch3-not-quite-file-3.rs

(limited to 'meap/meap-code/ch3/ch3-not-quite-file-3.rs')

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);
+}
\ No newline at end of file
-- 
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