Struct std::cell::RefMut
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[src]
pub struct RefMut<'b, T> where T: 'b + ?Sized {
// some fields omitted
}1.0.0A 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 U: ?Sized, F: FnOnce(&mut T) -> &mut U1.8.0
Make a new RefMut for a component of the borrowed data, e.g. an enum
variant.
The 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 used through Deref.
Example
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>
: can be built on RefMut::map: https://crates.io/crates/ref_filter_map
Make a new RefMut for an optional component of the borrowed data, e.g.
an enum variant.
The 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 used 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));