devela::_core::cell

Struct RefMut

1.6.0 · Source
pub struct RefMut<'b, T>
where T: 'b + ?Sized,
{ /* private fields */ }
Expand description

A wrapper type for a mutably borrowed value from a RefCell<T>.

See the module-level documentation for more.

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impl<'b, T> RefMut<'b, T>
where T: ?Sized,

1.8.0 · Source

pub fn map<U, F>(orig: RefMut<'b, T>, f: F) -> RefMut<'b, U>
where F: FnOnce(&mut T) -> &mut U, U: ?Sized,

Makes a new RefMut for a component of the borrowed data, e.g., an enum variant.

The RefCell is already mutably borrowed, so this cannot fail.

This is an associated function that needs to be used as RefMut::map(...). A method would interfere with methods of the same name on the contents of a RefCell used through Deref.

§Examples
use std::cell::{RefCell, RefMut};

let c = RefCell::new((5, 'b'));
{
    let b1: RefMut<'_, (u32, char)> = c.borrow_mut();
    let mut b2: RefMut<'_, u32> = RefMut::map(b1, |t| &mut t.0);
    assert_eq!(*b2, 5);
    *b2 = 42;
}
assert_eq!(*c.borrow(), (42, 'b'));
1.63.0 · Source

pub fn filter_map<U, F>( orig: RefMut<'b, T>, f: F, ) -> Result<RefMut<'b, U>, RefMut<'b, T>>
where F: FnOnce(&mut T) -> Option<&mut U>, U: ?Sized,

Makes a new RefMut for an optional component of the borrowed data. The original guard is returned as an Err(..) if the closure returns None.

The RefCell is already mutably borrowed, so this cannot fail.

This is an associated function that needs to be used as RefMut::filter_map(...). A method would interfere with methods of the same name on the contents of a RefCell used through Deref.

§Examples
use std::cell::{RefCell, RefMut};

let c = RefCell::new(vec![1, 2, 3]);

{
    let b1: RefMut<'_, Vec<u32>> = c.borrow_mut();
    let mut b2: Result<RefMut<'_, u32>, _> = RefMut::filter_map(b1, |v| v.get_mut(1));

    if let Ok(mut b2) = b2 {
        *b2 += 2;
    }
}

assert_eq!(*c.borrow(), vec![1, 4, 3]);
1.35.0 · Source

pub fn map_split<U, V, F>( orig: RefMut<'b, T>, f: F, ) -> (RefMut<'b, U>, RefMut<'b, V>)
where F: FnOnce(&mut T) -> (&mut U, &mut V), U: ?Sized, V: ?Sized,

Splits a RefMut into multiple RefMuts for different components of the borrowed data.

The underlying RefCell will remain mutably borrowed until both returned RefMuts go out of scope.

The RefCell is already mutably borrowed, so this cannot fail.

This is an associated function that needs to be used as RefMut::map_split(...). A method would interfere with methods of the same name on the contents of a RefCell used through Deref.

§Examples
use std::cell::{RefCell, RefMut};

let cell = RefCell::new([1, 2, 3, 4]);
let borrow = cell.borrow_mut();
let (mut begin, mut end) = RefMut::map_split(borrow, |slice| slice.split_at_mut(2));
assert_eq!(*begin, [1, 2]);
assert_eq!(*end, [3, 4]);
begin.copy_from_slice(&[4, 3]);
end.copy_from_slice(&[2, 1]);
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pub fn leak(orig: RefMut<'b, T>) -> &'b mut T

🔬This is a nightly-only experimental API. (cell_leak)

Converts into a mutable reference to the underlying data.

The underlying RefCell can not be borrowed from again and will always appear already mutably borrowed, making the returned reference the only to the interior.

This is an associated function that needs to be used as RefMut::leak(...). A method would interfere with methods of the same name on the contents of a RefCell used through Deref.

§Examples
#![feature(cell_leak)]
use std::cell::{RefCell, RefMut};
let cell = RefCell::new(0);

let value = RefMut::leak(cell.borrow_mut());
assert_eq!(*value, 0);
*value = 1;

assert!(cell.try_borrow_mut().is_err());

Trait Implementations§

1.0.0 · Source§

impl<T> Debug for RefMut<'_, T>
where T: Debug + ?Sized,

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

Formats the value using the given formatter. Read more
1.0.0 · Source§

impl<T> Deref for RefMut<'_, T>
where T: ?Sized,

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type Target = T

The resulting type after dereferencing.
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fn deref(&self) -> &T

Dereferences the value.
1.0.0 · Source§

impl<T> DerefMut for RefMut<'_, T>
where T: ?Sized,

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

Mutably dereferences the value.
1.20.0 · Source§

impl<T> Display for RefMut<'_, T>
where T: Display + ?Sized,

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

Formats the value using the given formatter. Read more
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impl<'b, T, U> CoerceUnsized<RefMut<'b, U>> for RefMut<'b, T>
where T: Unsize<U> + ?Sized, U: ?Sized,

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impl<T> DerefPure for RefMut<'_, T>
where T: ?Sized,

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impl<'b, T> PinCoerceUnsized for RefMut<'b, T>
where T: ?Sized,

Auto Trait Implementations§

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impl<'b, T> Freeze for RefMut<'b, T>
where T: ?Sized,

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impl<'b, T> !RefUnwindSafe for RefMut<'b, T>

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impl<'b, T> !Send for RefMut<'b, T>

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impl<'b, T> !Sync for RefMut<'b, T>

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impl<'b, T> Unpin for RefMut<'b, T>
where T: ?Sized,

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impl<'b, T> !UnwindSafe for RefMut<'b, T>

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> ArchivePointee for T

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type ArchivedMetadata = ()

The archived version of the pointer metadata for this type.
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fn pointer_metadata( _: &<T as ArchivePointee>::ArchivedMetadata, ) -> <T as Pointee>::Metadata

Converts some archived metadata to the pointer metadata for itself.
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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

Mutably borrows from an owned value. Read more
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impl<T> ByteSized for T

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const BYTE_ALIGN: usize = _

The alignment of this type in bytes.
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const BYTE_SIZE: usize = _

The size of this type in bytes.
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fn byte_align(&self) -> usize

Returns the alignment of this type in bytes.
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fn byte_size(&self) -> usize

Returns the size of this type in bytes. Read more
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fn ptr_size_ratio(&self) -> [usize; 2]

Returns the size ratio between Ptr::BYTES and BYTE_SIZE. Read more
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impl<T, R> Chain<R> for T
where T: ?Sized,

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fn chain<F>(self, f: F) -> R
where F: FnOnce(Self) -> R, Self: Sized,

Chain a function which takes the parameter by value.
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fn chain_ref<F>(&self, f: F) -> R
where F: FnOnce(&Self) -> R,

Chain a function which takes the parameter by shared reference.
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fn chain_mut<F>(&mut self, f: F) -> R
where F: FnOnce(&mut Self) -> R,

Chain a function which takes the parameter by exclusive reference.
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impl<T> ExtAny for T
where T: Any + ?Sized,

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fn type_id() -> TypeId

Returns the TypeId of Self. Read more
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fn type_of(&self) -> TypeId

Returns the TypeId of self. Read more
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fn type_name(&self) -> &'static str

Returns the type name of self. Read more
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fn type_is<T: 'static>(&self) -> bool

Returns true if Self is of type T. Read more
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fn as_any_ref(&self) -> &dyn Any
where Self: Sized,

Upcasts &self as &dyn Any. Read more
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fn as_any_mut(&mut self) -> &mut dyn Any
where Self: Sized,

Upcasts &mut self as &mut dyn Any. Read more
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fn as_any_box(self: Box<Self>) -> Box<dyn Any>
where Self: Sized,

Upcasts Box<self> as Box<dyn Any>. Read more
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fn downcast_ref<T: 'static>(&self) -> Option<&T>

Available on crate feature unsafe_layout only.
Returns some shared reference to the inner value if it is of type T. Read more
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fn downcast_mut<T: 'static>(&mut self) -> Option<&mut T>

Available on crate feature unsafe_layout only.
Returns some exclusive reference to the inner value if it is of type T. Read more
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impl<T> ExtMem for T
where T: ?Sized,

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const NEEDS_DROP: bool = _

Know whether dropping values of this type matters, in compile-time.
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fn mem_align_of<T>() -> usize

Returns the minimum alignment of the type in bytes. Read more
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fn mem_align_of_val(&self) -> usize

Returns the alignment of the pointed-to value in bytes. Read more
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fn mem_size_of<T>() -> usize

Returns the size of a type in bytes. Read more
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fn mem_size_of_val(&self) -> usize

Returns the size of the pointed-to value in bytes. Read more
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fn mem_copy(&self) -> Self
where Self: Copy,

Bitwise-copies a value. Read more
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fn mem_needs_drop(&self) -> bool

Returns true if dropping values of this type matters. Read more
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fn mem_drop(self)
where Self: Sized,

Drops self by running its destructor. Read more
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fn mem_forget(self)
where Self: Sized,

Forgets about self without running its destructor. Read more
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fn mem_replace(&mut self, other: Self) -> Self
where Self: Sized,

Replaces self with other, returning the previous value of self. Read more
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fn mem_take(&mut self) -> Self
where Self: Default,

Replaces self with its default value, returning the previous value of self. Read more
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fn mem_swap(&mut self, other: &mut Self)
where Self: Sized,

Swaps the value of self and other without deinitializing either one. Read more
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unsafe fn mem_zeroed<T>() -> T

Available on crate feature unsafe_layout only.
Returns the value of type T represented by the all-zero byte-pattern. Read more
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unsafe fn mem_transmute_copy<Src, Dst>(src: &Src) -> Dst

Available on crate feature unsafe_layout only.
Returns the value of type T represented by the all-zero byte-pattern. Read more
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fn mem_as_bytes(&self) -> &[u8]
where Self: Sync + Unpin,

Available on crate feature unsafe_slice only.
View a Sync + Unpin self as &[u8]. Read more
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fn mem_as_bytes_mut(&mut self) -> &mut [u8]
where Self: Sync + Unpin,

Available on crate feature unsafe_slice only.
View a Sync + Unpin self as &mut [u8]. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<S> FromSample<S> for S

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fn from_sample_(s: S) -> S

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impl<T> Hook for T

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fn hook_ref<F>(self, f: F) -> Self
where F: FnOnce(&Self),

Applies a function which takes the parameter by shared reference, and then returns the (possibly) modified owned value. Read more
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fn hook_mut<F>(self, f: F) -> Self
where F: FnOnce(&mut Self),

Applies a function which takes the parameter by exclusive reference, and then returns the (possibly) modified owned value. Read more
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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

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

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impl<T> IntoEither for T

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fn into_either(self, into_left: bool) -> Either<Self, Self>

Converts self into a Left variant of Either<Self, Self> if into_left is true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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fn into_either_with<F>(self, into_left: F) -> Either<Self, Self>
where F: FnOnce(&Self) -> bool,

Converts self into a Left variant of Either<Self, Self> if into_left(&self) returns true. Converts self into a Right variant of Either<Self, Self> otherwise. Read more
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impl<F, T> IntoSample<T> for F
where T: FromSample<F>,

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fn into_sample(self) -> T

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impl<T> LayoutRaw for T

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fn layout_raw(_: <T as Pointee>::Metadata) -> Result<Layout, LayoutError>

Returns the layout of the type.
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impl<T, N1, N2> Niching<NichedOption<T, N1>> for N2
where T: SharedNiching<N1, N2>, N1: Niching<T>, N2: Niching<T>,

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unsafe fn is_niched(niched: *const NichedOption<T, N1>) -> bool

Returns whether the given value has been niched. Read more
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fn resolve_niched(out: Place<NichedOption<T, N1>>)

Writes data to out indicating that a T is niched.
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impl<T> Pointable for T

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const ALIGN: usize

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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impl<T> Pointee for T

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type Metadata = ()

The metadata type for pointers and references to this type.
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impl<P, T> Receiver for P
where P: Deref<Target = T> + ?Sized, T: ?Sized,

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type Target = T

🔬This is a nightly-only experimental API. (arbitrary_self_types)
The target type on which the method may be called.
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impl<T, U> ToSample<U> for T
where U: FromSample<T>,

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fn to_sample_(self) -> U

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impl<T> ToString for T
where T: Display + ?Sized,

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fn to_string(&self) -> String

Converts the given value to a String. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more
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impl<S, T> Duplex<S> for T
where T: FromSample<S> + ToSample<S>,