Enum Managed

pub enum Managed<'a, T: 'a + ?Sized> {
    Borrowed(&'a mut T),
    Owned(Box<T>),
}

A managed object.

This enum can be used to represent exclusive access to objects. In Rust, exclusive access to an object is obtained by either owning the object, or owning a mutable pointer to the object; hence, “managed”.

The purpose of this enum is providing good ergonomics with std present while making it possible to avoid having a heap at all (which of course means that std is not present). To achieve this, the variants other than Borrow are only available when the corresponding feature is opted in.

A function that requires a managed object should be generic over an Into<Managed<'a, T>> argument; then, it will be possible to pass either a Box<T>, Vec<T>, or a &'a mut T without any conversion at the call site.

Note that a Vec<T> converted into an Into<Managed<'a, [T]>> gets transformed into a boxed slice, and can no longer be resized. See also ManagedSlice, which does not have this drawback.

Variants

Borrowed(&'a mut T)

Borrowed variant.

Owned(Box<T>)

Owned variant, only available with the std or alloc feature enabled.

Trait Implementations

impl<'a, T> Debug for Managed<'a, T>

where T: Debug + 'a + ?Sized,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'a, T: 'a + ?Sized> Deref for Managed<'a, T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<'a, T: 'a + ?Sized> DerefMut for Managed<'a, T>

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<'a, T: 'a + ?Sized> From<&'a mut T> for Managed<'a, T>

fn from(value: &'a mut T) -> Self

Converts to this type from the input type.

impl<'a, T: ?Sized + 'a> From<Box<T>> for Managed<'a, T>

fn from(value: Box<T>) -> Self

Converts to this type from the input type.

impl<'a, T: 'a> From<Vec<T>> for Managed<'a, [T]>

fn from(value: Vec<T>) -> Self

Converts to this type from the input type.