Struct maybe_dangling::MaybeDangling

pub struct MaybeDangling<T> { /* private fields */ }

Like crate::ManuallyDrop but for having drop glue. This wrapper is 0-cost.

In other words, a MaybeDangling<T> is just like T, but for having been stripped of aliasing/dereferenceable-ity properties.

Its usage should be quite rare and advanced: if you are intending to keep hold of a potentially dangling / exhausted value, chances are you won’t want implicit/automatic drop glue of it without having previously checked for lack of exhaustion ⚠️.

That is, it is strongly advisable to be using crate::ManuallyDrop<T> instead!

Opting into #[may_dangle] and the dropck_eyepatch

Ironically, for this drop glue to be as smooth as it should be, the unstable #[may_dangle] feature is needed.

But by virtue of being unstable, it cannot be offered by this crate on stable Rust.

For the adventurous nightly users, you can enable the nightly-dropck_eyepatch Cargo feature to opt into the usage of the eponymous rustc feature so as to get the Drop impl amended accordingly.

Implementations

impl<T> MaybeDangling<T>

pub const fn new(value: T) -> MaybeDangling<T>

pub fn into_inner(slot: MaybeDangling<T>) -> T

Extracts the value from the MaybeDangling container.

See ::core::mem::ManuallyDrop::into_inner() for more info.

Trait Implementations

impl<T: Clone> Clone for MaybeDangling<T>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for MaybeDangling<T>

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

See ::core::mem::ManuallyDrop::fmt() for more info. See ::core::mem::ManuallyDrop::fmt() for more info.

impl<T: Default> Default for MaybeDangling<T>

fn default() -> Self

Returns the “default value” for a type.

impl<T> Deref for MaybeDangling<T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<T> DerefMut for MaybeDangling<T>

fn deref_mut(&mut self) -> &mut T

Mutably dereferences the value.

impl<T> Drop for MaybeDangling<T>

fn drop(&mut self)

Executes the destructor for this type.

impl<T: Hash> Hash for MaybeDangling<T>

fn hash<__H: Hasher>(&self, state: &mut __H)

See ::core::mem::ManuallyDrop::hash() for more info. See ::core::mem::ManuallyDrop::hash() for more info.

fn hash_slice<H>(data: &[Self], state: &mut H)where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<T: Ord> Ord for MaybeDangling<T>

fn cmp(&self, other: &Self) -> Ordering

See ::core::mem::ManuallyDrop::cmp() for more info. See ::core::mem::ManuallyDrop::cmp() for more info.

fn max(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Selfwhere Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Selfwhere Self: Sized + PartialOrd<Self>,

Restrict a value to a certain interval.

impl<T: PartialEq> PartialEq<MaybeDangling<T>> for MaybeDangling<T>

fn eq(&self, other: &Self) -> bool

See ::core::mem::ManuallyDrop::eq() for more info. See ::core::mem::ManuallyDrop::eq() for more info.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T: PartialOrd> PartialOrd<MaybeDangling<T>> for MaybeDangling<T>

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

See ::core::mem::ManuallyDrop::partial_cmp() for more info. See ::core::mem::ManuallyDrop::partial_cmp() for more info.

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<T: Eq> Eq for MaybeDangling<T>