Struct Guard 

pub struct Guard<T, F>
where
    F: FnOnce(T),
{ /* private fields */ }

Wrap a value and run a closure when dropped.

This is useful for quickly creating desructors inline.

Examples

{
    // Create a new guard around a string that will
    // print its value when dropped.
    let s = String::from("Chashu likes tuna");
    let mut s = Guard::new(s, |s| println!("{s}"));
     
    // Modify the string contained in the guard.
    s.push_str("!!!");
     
    // The guard will be dropped here.
}

Implementations

impl<T, F> Guard<T, F>

where F: FnOnce(T),

pub fn new(inner: T, f: F) -> Self

Create a new instance of Guard.

Example

let value = String::from("Chashu likes tuna");
let guard = Guard::new(value, |s| println!("{s}"));

pub fn into_inner(guard: Self) -> T

Consumes the Guard, returning the wrapped value.

This will not execute the closure. This is implemented as a static method to prevent any potential conflicts with any other methods called into_inner inherited via the Deref and DerefMut impls.

Example

let value = String::from("Nori likes chicken");
let guard = Guard::new(value, |s| println!("{s}"));
assert_eq!(Guard::into_inner(guard), "Nori likes chicken");

Trait Implementations

impl<T: Debug, F> Debug for Guard<T, F>

where F: FnOnce(T) + Debug,

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

Formats the value using the given formatter.

impl<T, F> Deref for Guard<T, F>

where F: FnOnce(T),

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<T, F> DerefMut for Guard<T, F>

where F: FnOnce(T),

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

Mutably dereferences the value.

impl<T, F> Drop for Guard<T, F>

where F: FnOnce(T),

fn drop(&mut self)

Executes the destructor for this type.

impl<T: Hash, F> Hash for Guard<T, F>

where F: FnOnce(T) + Hash,

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

Feeds this value into the given Hasher.

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, F> Ord for Guard<T, F>

where F: FnOnce(T) + Ord,

fn cmp(&self, other: &Guard<T, F>) -> Ordering

This method returns an Ordering between self and other.

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

where Self: Sized,

Compares and returns the maximum of two values.

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

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl<T: PartialEq, F> PartialEq for Guard<T, F>

where F: FnOnce(T) + PartialEq,

fn eq(&self, other: &Guard<T, F>) -> bool

Tests for self and other values to be equal, and is used by ==.

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

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

impl<T: PartialOrd, F> PartialOrd for Guard<T, F>

where F: FnOnce(T) + PartialOrd,

fn partial_cmp(&self, other: &Guard<T, F>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

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

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

Tests greater than (for self and other) and is used by the > operator.

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

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

impl<T: Eq, F> Eq for Guard<T, F>

where F: FnOnce(T) + Eq,

impl<T, F> StructuralPartialEq for Guard<T, F>

where F: FnOnce(T),