Created
June 27, 2019 13:44
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#[derive(Clone, Copy)] | |
pub struct MyStruct<'a> { | |
name: &'a str, | |
} | |
impl<'a> MyStruct<'a> { | |
fn new() -> Self { | |
MyStruct { name: "Before" } | |
} | |
fn read(&self) { | |
print!("Value is {}\n", self.name); | |
} | |
fn write(&mut self) { | |
self.name = "After"; | |
print!("Value is now {}\n", self.name); | |
} | |
} | |
fn error_fn() { | |
let mut ms = MyStruct::new(); | |
let reader = &ms; | |
reader.read(); | |
// let mut _writer = &mut ms; // Error: cannot borrow `ms` as mutable because it is also borrowed as immutable | |
} | |
fn good_fn() { | |
let mut ms = MyStruct::new(); | |
{ | |
let reader = &ms; | |
reader.read(); | |
} | |
{ | |
let mut _writer = &mut ms; | |
_writer.write(); | |
} | |
{ | |
let reader = &ms; | |
reader.read(); | |
} | |
} | |
fn cell_fn() { | |
let mut c = std::cell::Cell::new(MyStruct::new()); | |
c.get().read(); | |
c.get_mut().write(); | |
c.get().read(); | |
c.get_mut().write(); | |
} | |
fn main() { | |
error_fn(); | |
cell_fn(); | |
} |
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