pub struct BorrowBag<V> { /* private fields */ }
Expand description

BorrowBag allows the storage of any value using add(T), and returns a Handle which can be used to borrow the value back later. As the BorrowBag is add-only, Handle values remain valid for the lifetime of the BorrowBag.

After being added, the Handle can be passed to borrow(Handle), which will return a reference to the value.

Example

use borrow_bag::BorrowBag;

#[derive(PartialEq, Debug)]
struct X;

#[derive(PartialEq, Debug)]
struct Y;

#[derive(PartialEq, Debug)]
struct Z;

let bag = BorrowBag::new();
let (bag, x_handle) = bag.add(X);
let (bag, y_handle) = bag.add(Y);
let (bag, z_handle) = bag.add(Z);

let x: &X = bag.borrow(x_handle);
assert_eq!(x, &X);
let y: &Y = bag.borrow(y_handle);
assert_eq!(y, &Y);
let z: &Z = bag.borrow(z_handle);
assert_eq!(z, &Z);

// Can borrow multiple times using the same handle
let x: &X = bag.borrow(x_handle);
assert_eq!(x, &X);

Implementations

Creates a new, empty BorrowBag.

Adds a value to the bag, and returns a tuple containing:

  1. The new bag containing the added element; and
  2. A Handle which can be used to retrieve the added element.

The trait bound is used to constrain and define the BorrowBag implementation, but is not intended to provide any restrictions on the value being added.

let bag = BorrowBag::new();
// Consumes the empty `bag`, and produces a new `bag` containing the value. The `handle`
// can be used to borrow the value back later.
let (bag, handle) = bag.add(15u8);

Borrows a value previously added to the bag.

let i: &u8 = bag.borrow(handle);
assert_eq!(*i, 15);

Trait Implementations

Returns the “default value” for a type. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.