Struct std::cell::RefMut
[−]
[src]
pub struct RefMut<'b, T> where T: 'b + ?Sized {
// some fields omitted
}
A wrapper type for a mutably borrowed value from a RefCell<T>
.
See the module-level documentation for more.
Methods
impl<'b, T> RefMut<'b, T> where T: ?Sized
fn map<U, F>(orig: RefMut<'b, T>, f: F) -> RefMut<'b, U> where F: FnOnce(&mut T) -> &mut U, U: ?Sized
: recently added
Make a new RefMut
`RefMut` for a component of the borrowed data, e.g. an enum
variant.
The RefCell
`RefCell` is already mutably borrowed, so this cannot fail.
This is an associated function that needs to be used as
RefMut::map(...)
. A method would interfere with methods of the same
name on the contents of a RefCell
`RefCellused through
Deref`.
Example
#![feature(cell_extras)] fn main() { use std::cell::{RefCell, RefMut}; let c = RefCell::new((5, 'b')); { let b1: RefMut<(u32, char)> = c.borrow_mut(); let mut b2: RefMut<u32> = RefMut::map(b1, |t| &mut t.0); assert_eq!(*b2, 5); *b2 = 42; } assert_eq!(*c.borrow(), (42, 'b')); }use std::cell::{RefCell, RefMut}; let c = RefCell::new((5, 'b')); { let b1: RefMut<(u32, char)> = c.borrow_mut(); let mut b2: RefMut<u32> = RefMut::map(b1, |t| &mut t.0); assert_eq!(*b2, 5); *b2 = 42; } assert_eq!(*c.borrow(), (42, 'b'));
fn filter_map<U, F>(orig: RefMut<'b, T>, f: F) -> Option<RefMut<'b, U>> where U: ?Sized, F: FnOnce(&mut T) -> Option<&mut U>
: recently added
Make a new RefMut
`RefMut` for a optional component of the borrowed data, e.g.
an enum variant.
The RefCell
`RefCell` is already mutably borrowed, so this cannot fail.
This is an associated function that needs to be used as
RefMut::filter_map(...)
. A method would interfere with methods of the
same name on the contents of a RefCell
`RefCellused through
Deref`.
Example
#![feature(cell_extras)] fn main() { use std::cell::{RefCell, RefMut}; let c = RefCell::new(Ok(5)); { let b1: RefMut<Result<u32, ()>> = c.borrow_mut(); let mut b2: RefMut<u32> = RefMut::filter_map(b1, |o| { o.as_mut().ok() }).unwrap(); assert_eq!(*b2, 5); *b2 = 42; } assert_eq!(*c.borrow(), Ok(42)); }use std::cell::{RefCell, RefMut}; let c = RefCell::new(Ok(5)); { let b1: RefMut<Result<u32, ()>> = c.borrow_mut(); let mut b2: RefMut<u32> = RefMut::filter_map(b1, |o| { o.as_mut().ok() }).unwrap(); assert_eq!(*b2, 5); *b2 = 42; } assert_eq!(*c.borrow(), Ok(42));