pub struct RefMut<'b, T> where
T: 'b + 'b + ?Sized, { /* fields omitted */ }
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
.
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'));
pub fn map_split<U, V, F>( orig: RefMut<'b, T>, f: F ) -> (RefMut<'b, U>, RefMut<'b, V>) where F: FnOnce(&mut T) -> (&mut U, &mut V), U: ?Sized, V: ?Sized, | [src] |
🔬 This is a nightly-only experimental API. (refcell_map_split
)
Split a RefMut
into multiple RefMut
s for different components of the
borrowed data.
The underlying RefCell
will remain mutably borrowed until both
returned RefMut
s go out of scope.
The RefCell
is already mutably borrowed, so this cannot fail.
This is an associated function that needs to be used as
RefMut::map_split(...)
. A method would interfere with methods of the
same name on the contents of a RefCell
used through Deref
.
#![feature(refcell_map_split)]
use std::cell::{RefCell, RefMut};
let cell = RefCell::new([1, 2, 3, 4]);
let borrow = cell.borrow_mut();
let (mut begin, mut end) = RefMut::map_split(borrow, |slice| slice.split_at_mut(2));
assert_eq!(*begin, [1, 2]);
assert_eq!(*end, [3, 4]);
begin.copy_from_slice(&[4, 3]);
end.copy_from_slice(&[2, 1]);
Formats the value using the given formatter. Read more
Formats the value using the given formatter. Read more
Mutably dereferences the value.
type Target = T
The resulting type after dereferencing.
Converts the given value to a String
. Read more
type Error = !
🔬 This is a nightly-only experimental API. (try_from
)
The type returned in the event of a conversion error.
🔬 This is a nightly-only experimental API. (try_from
)
Immutably borrows from an owned value. Read more
🔬 This is a nightly-only experimental API. (get_type_id
)
this method will likely be replaced by an associated static
type Error = <U as TryFrom<T>>::Error
🔬 This is a nightly-only experimental API. (try_from
)
The type returned in the event of a conversion error.
🔬 This is a nightly-only experimental API. (try_from
)
Mutably borrows from an owned value. Read more