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-rwxr-xr-xmeap/meap-code/ch3/ch3-not-quite-file-3.rs55
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 100755
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