use std::sync::{Arc, Mutex};

struct MyStruct
{
    pub field1: Option<Vec<String>>
}

impl MyStruct
{
    pub fn new() -> Self
    {
        Self
        {
            field1: None,
        }
    }

    pub fn new_arc_mutex() -> Arc<Mutex<Self>>
    {
        Arc::new(Mutex::new(Self::new()))
    }
}

fn main()
{
    let ms = MyStruct::new_arc_mutex();

    let mut ms = ms.lock().unwrap();
    ms.field1 = Some(vec!());

    let mut v = ms.field1.as_mut();
    match v {
        Some(val) => val.push("Hello World!".to_owned()),
        None => {}
    }

}