Type Alias OptionalWriter

pub type OptionalWriter<T> = EitherWriter<T, Sink>;

Available on crate features fmt and std only.

A writer which may or may not be enabled.

This may be used by MakeWriter implementations that wish to conditionally enable or disable the returned writer based on a span or event’s Metadata.

Aliased Type

enum OptionalWriter<T> {
    A(T),
    B(Sink),
}

Variants

A(T)

A writer of type A.

B(Sink)

A writer of type B.

Implementations

impl<T> OptionalWriter<T>

pub fn none() -> Self

Returns a disabled writer.

Any bytes written to the returned writer are discarded.

This is equivalent to returning Option::None.

pub fn some(t: T) -> Self

Returns an enabled writer of type T.

This is equivalent to returning Option::Some.

Trait Implementations

impl<T> From<Option<T>> for OptionalWriter<T>

fn from(opt: Option<T>) -> Self

Converts to this type from the input type.

impl<A: Clone, B: Clone> Clone for EitherWriter<A, B>

fn clone(&self) -> EitherWriter<A, B>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<A: Debug, B: Debug> Debug for EitherWriter<A, B>

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

Formats the value using the given formatter.

impl<A: PartialEq, B: PartialEq> PartialEq for EitherWriter<A, B>

fn eq(&self, other: &EitherWriter<A, B>) -> 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<A, B> Write for EitherWriter<A, B>

where A: Write, B: Write,

fn write(&mut self, buf: &[u8]) -> Result<usize>

Writes a buffer into this writer, returning how many bytes were written.

fn flush(&mut self) -> Result<()>

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize>

Like write, except that it writes from a slice of buffers.

fn write_all(&mut self, buf: &[u8]) -> Result<()>

Attempts to write an entire buffer into this writer.

fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<()>

Writes a formatted string into this writer, returning any error encountered.

fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector #69941)

Determines if this Writer has an efficient write_vectored implementation.

fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

🔬This is a nightly-only experimental API. (write_all_vectored #70436)

Attempts to write multiple buffers into this writer.

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

Creates a “by reference” adapter for this instance of Write.

impl<A: Copy, B: Copy> Copy for EitherWriter<A, B>

impl<A: Eq, B: Eq> Eq for EitherWriter<A, B>

impl<A, B> StructuralPartialEq for EitherWriter<A, B>