static variable with BufWriter in Rust

I would like to get a global variable with BufWriter.

This code is executed without errors, but writing to the file is not carried out:

lazy_static! {
    static ref WRITER: Mutex<BufWriter<File>> = {
        let file = File::create("test.bin").unwrap();
        BufWriter::new(file).into()
    }
}
WRITER.lock().unwrap().write_all(&vec![1, 2, 3, 4]).unwrap();

>Solution :

Two things come into play:

• A BufWriter absorbes writes in memory before handing them to the operating system until either
  • Its buffer is full
  • It has flush called
  • It gets Dropped
• lazy_static items are never Dropped

So, to make your code work, you must do something like

let mut writer = WRITER.lock().unwrap();
writer.write_all(&vec![1, 2, 3, 4]).unwrap();
writer.flush().unwrap();

Playground (with one minor syntax error fixed)

Alternatively:

• You construct the BufWriter in your main function and hand a reference to it through all method calls.
• A bit dirty, but you could use dtor.