Trait enso_prelude::IndexMut 1.0.0[−][src]
pub trait IndexMut<Idx>: Index<Idx> where
Idx: ?Sized, { fn index_mut(&mut self, index: Idx) -> &mut Self::Output; }
Expand description
Used for indexing operations (container[index]
) in mutable contexts.
container[index]
is actually syntactic sugar for
*container.index_mut(index)
, but only when used as a mutable value. If
an immutable value is requested, the Index
trait is used instead. This
allows nice things such as v[index] = value
.
Examples
A very simple implementation of a Balance
struct that has two sides, where
each can be indexed mutably and immutably.
use std::ops::{Index, IndexMut}; #[derive(Debug)] enum Side { Left, Right, } #[derive(Debug, PartialEq)] enum Weight { Kilogram(f32), Pound(f32), } struct Balance { pub left: Weight, pub right: Weight, } impl Index<Side> for Balance { type Output = Weight; fn index(&self, index: Side) -> &Self::Output { println!("Accessing {:?}-side of balance immutably", index); match index { Side::Left => &self.left, Side::Right => &self.right, } } } impl IndexMut<Side> for Balance { fn index_mut(&mut self, index: Side) -> &mut Self::Output { println!("Accessing {:?}-side of balance mutably", index); match index { Side::Left => &mut self.left, Side::Right => &mut self.right, } } } let mut balance = Balance { right: Weight::Kilogram(2.5), left: Weight::Pound(1.5), }; // In this case, `balance[Side::Right]` is sugar for // `*balance.index(Side::Right)`, since we are only *reading* // `balance[Side::Right]`, not writing it. assert_eq!(balance[Side::Right], Weight::Kilogram(2.5)); // However, in this case `balance[Side::Left]` is sugar for // `*balance.index_mut(Side::Left)`, since we are writing // `balance[Side::Left]`. balance[Side::Left] = Weight::Kilogram(3.0);
Required methods
Implementations on Foreign Types
impl<I> IndexMut<I> for str where
I: SliceIndex<str>,
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impl<I> IndexMut<I> for str where
I: SliceIndex<str>,
[src]pub fn index_mut(&mut self, index: I) -> &mut <I as SliceIndex<str>>::Output
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impl IndexMut<RangeInclusive<usize>> for String
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impl IndexMut<RangeInclusive<usize>> for String
[src]pub fn index_mut(&mut self, index: RangeInclusive<usize>) -> &mut str
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impl IndexMut<RangeToInclusive<usize>> for String
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impl IndexMut<RangeToInclusive<usize>> for String
[src]pub fn index_mut(&mut self, index: RangeToInclusive<usize>) -> &mut str
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impl<'a, K, V, S> IndexMut<&'a <K as WeakElement>::Strong> for PtrWeakKeyHashMap<K, V, S> where
S: BuildHasher,
K: WeakElement,
<K as WeakElement>::Strong: Deref,
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impl<'a, K, V, S> IndexMut<&'a <K as WeakElement>::Strong> for PtrWeakKeyHashMap<K, V, S> where
S: BuildHasher,
K: WeakElement,
<K as WeakElement>::Strong: Deref,
[src]pub fn index_mut(
&mut self,
index: &'a <K as WeakElement>::Strong
) -> &mut <PtrWeakKeyHashMap<K, V, S> as Index<&'a <K as WeakElement>::Strong>>::Output
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&mut self,
index: &'a <K as WeakElement>::Strong
) -> &mut <PtrWeakKeyHashMap<K, V, S> as Index<&'a <K as WeakElement>::Strong>>::Output
impl<T, R, C, S> IndexMut<(usize, usize)> for Matrix<T, R, C, S> where
C: Dim,
T: Scalar,
R: Dim,
S: StorageMut<T, R, C>,
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impl<T, R, C, S> IndexMut<(usize, usize)> for Matrix<T, R, C, S> where
C: Dim,
T: Scalar,
R: Dim,
S: StorageMut<T, R, C>,
[src]impl<T, R, C, S> IndexMut<usize> for Matrix<T, R, C, S> where
C: Dim,
T: Scalar,
R: Dim,
S: StorageMut<T, R, C>,
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impl<T, R, C, S> IndexMut<usize> for Matrix<T, R, C, S> where
C: Dim,
T: Scalar,
R: Dim,
S: StorageMut<T, R, C>,
[src]impl<T> IndexMut<usize> for DualQuaternion<T> where
T: SimdRealField,
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impl<T> IndexMut<usize> for DualQuaternion<T> where
T: SimdRealField,
[src]impl<T, const D: usize> IndexMut<(usize, usize)> for Transform<T, TGeneral, D> where
T: RealField,
Const<D>: DimNameAdd<Const<1_usize>>,
DefaultAllocator: Allocator<T, <Const<D> as DimNameAdd<Const<1_usize>>>::Output, <Const<D> as DimNameAdd<Const<1_usize>>>::Output>,
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impl<T, const D: usize> IndexMut<(usize, usize)> for Transform<T, TGeneral, D> where
T: RealField,
Const<D>: DimNameAdd<Const<1_usize>>,
DefaultAllocator: Allocator<T, <Const<D> as DimNameAdd<Const<1_usize>>>::Output, <Const<D> as DimNameAdd<Const<1_usize>>>::Output>,
[src]impl<T> IndexMut<usize> for Quaternion<T> where
T: Scalar,
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impl<T> IndexMut<usize> for Quaternion<T> where
T: Scalar,
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