Struct std::mem::ManuallyDrop 1.20.0[−][src]
#[lang = "manually_drop"]pub struct ManuallyDrop<T> { /* fields omitted */ }
A wrapper to inhibit compiler from automatically calling T’s destructor.
This wrapper is 0-cost.
Examples
This wrapper helps with explicitly documenting the drop order dependencies between fields of the type:
use std::mem::ManuallyDrop; struct Peach; struct Banana; struct Melon; struct FruitBox { // Immediately clear there’s something non-trivial going on with these fields. peach: ManuallyDrop<Peach>, melon: Melon, // Field that’s independent of the other two. banana: ManuallyDrop<Banana>, } impl Drop for FruitBox { fn drop(&mut self) { unsafe { // Explicit ordering in which field destructors are run specified in the intuitive // location – the destructor of the structure containing the fields. // Moreover, one can now reorder fields within the struct however much they want. ManuallyDrop::drop(&mut self.peach); ManuallyDrop::drop(&mut self.banana); } // After destructor for `FruitBox` runs (this function), the destructor for Melon gets // invoked in the usual manner, as it is not wrapped in `ManuallyDrop`. } }Run
Methods
impl<T> ManuallyDrop<T>[src]
impl<T> ManuallyDrop<T>pub const fn new(value: T) -> ManuallyDrop<T>[src]
pub const fn new(value: T) -> ManuallyDrop<T>Wrap a value to be manually dropped.
Examples
use std::mem::ManuallyDrop; ManuallyDrop::new(Box::new(()));Run
pub fn into_inner(slot: ManuallyDrop<T>) -> T[src]
pub fn into_inner(slot: ManuallyDrop<T>) -> TExtract the value from the ManuallyDrop container.
Examples
use std::mem::ManuallyDrop; let x = ManuallyDrop::new(Box::new(())); let _: Box<()> = ManuallyDrop::into_inner(x);Run
pub unsafe fn drop(slot: &mut ManuallyDrop<T>)[src]
pub unsafe fn drop(slot: &mut ManuallyDrop<T>)Manually drops the contained value.
Safety
This function runs the destructor of the contained value and thus the wrapped value now represents uninitialized data. It is up to the user of this method to ensure the uninitialized data is not actually used.
Trait Implementations
impl<T> Hash for ManuallyDrop<T> where
T: Hash, [src]
impl<T> Hash for ManuallyDrop<T> where
T: Hash, fn hash<__HT>(&self, state: &mut __HT) where
__HT: Hasher, [src]
fn hash<__HT>(&self, state: &mut __HT) where
__HT: Hasher, Feeds this value into the given [Hasher]. Read more
fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher, 1.3.0[src]
fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher, Feeds a slice of this type into the given [Hasher]. Read more
impl<T> Clone for ManuallyDrop<T> where
T: Clone, [src]
impl<T> Clone for ManuallyDrop<T> where
T: Clone, fn clone(&self) -> ManuallyDrop<T>[src]
fn clone(&self) -> ManuallyDrop<T>Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)1.0.0[src]
fn clone_from(&mut self, source: &Self)Performs copy-assignment from source. Read more
impl<T> Debug for ManuallyDrop<T> where
T: Debug, [src]
impl<T> Debug for ManuallyDrop<T> where
T: Debug, fn fmt(&self, f: &mut Formatter) -> Result<(), Error>[src]
fn fmt(&self, f: &mut Formatter) -> Result<(), Error>Formats the value using the given formatter. Read more
impl<T> PartialOrd<ManuallyDrop<T>> for ManuallyDrop<T> where
T: PartialOrd<T>, [src]
impl<T> PartialOrd<ManuallyDrop<T>> for ManuallyDrop<T> where
T: PartialOrd<T>, fn partial_cmp(&self, other: &ManuallyDrop<T>) -> Option<Ordering>[src]
fn partial_cmp(&self, other: &ManuallyDrop<T>) -> Option<Ordering>This method returns an ordering between self and other values if one exists. Read more
fn lt(&self, other: &ManuallyDrop<T>) -> bool[src]
fn lt(&self, other: &ManuallyDrop<T>) -> boolThis method tests less than (for self and other) and is used by the < operator. Read more
fn le(&self, other: &ManuallyDrop<T>) -> bool[src]
fn le(&self, other: &ManuallyDrop<T>) -> boolThis method tests less than or equal to (for self and other) and is used by the <= operator. Read more
fn gt(&self, other: &ManuallyDrop<T>) -> bool[src]
fn gt(&self, other: &ManuallyDrop<T>) -> boolThis method tests greater than (for self and other) and is used by the > operator. Read more
fn ge(&self, other: &ManuallyDrop<T>) -> bool[src]
fn ge(&self, other: &ManuallyDrop<T>) -> boolThis method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
impl<T> Ord for ManuallyDrop<T> where
T: Ord, [src]
impl<T> Ord for ManuallyDrop<T> where
T: Ord, fn cmp(&self, other: &ManuallyDrop<T>) -> Ordering[src]
fn cmp(&self, other: &ManuallyDrop<T>) -> OrderingThis method returns an Ordering between self and other. Read more
fn max(self, other: Self) -> Self1.21.0[src]
fn max(self, other: Self) -> SelfCompares and returns the maximum of two values. Read more
fn min(self, other: Self) -> Self1.21.0[src]
fn min(self, other: Self) -> SelfCompares and returns the minimum of two values. Read more
impl<T> Eq for ManuallyDrop<T> where
T: Eq, [src]
impl<T> Eq for ManuallyDrop<T> where
T: Eq, impl<T> PartialEq<ManuallyDrop<T>> for ManuallyDrop<T> where
T: PartialEq<T>, [src]
impl<T> PartialEq<ManuallyDrop<T>> for ManuallyDrop<T> where
T: PartialEq<T>, fn eq(&self, other: &ManuallyDrop<T>) -> bool[src]
fn eq(&self, other: &ManuallyDrop<T>) -> boolThis method tests for self and other values to be equal, and is used by ==. Read more
fn ne(&self, other: &ManuallyDrop<T>) -> bool[src]
fn ne(&self, other: &ManuallyDrop<T>) -> boolThis method tests for !=.
impl<T> Copy for ManuallyDrop<T> where
T: Copy, [src]
impl<T> Copy for ManuallyDrop<T> where
T: Copy, impl<T> Default for ManuallyDrop<T> where
T: Default, [src]
impl<T> Default for ManuallyDrop<T> where
T: Default, fn default() -> ManuallyDrop<T>[src]
fn default() -> ManuallyDrop<T>Returns the "default value" for a type. Read more
impl<T> DerefMut for ManuallyDrop<T>[src]
impl<T> DerefMut for ManuallyDrop<T>fn deref_mut(&mut self) -> &mut <ManuallyDrop<T> as Deref>::Target[src]
fn deref_mut(&mut self) -> &mut <ManuallyDrop<T> as Deref>::TargetMutably dereferences the value.
impl<T> Deref for ManuallyDrop<T>[src]
impl<T> Deref for ManuallyDrop<T>Auto Trait Implementations
impl<T> Send for ManuallyDrop<T> where
T: Send,
impl<T> Send for ManuallyDrop<T> where
T: Send, impl<T> Sync for ManuallyDrop<T> where
T: Sync,
impl<T> Sync for ManuallyDrop<T> where
T: Sync,