Struct BoxMakeWriter

pub struct BoxMakeWriter { /* private fields */ }

Available on crate features fmt and std only.

A writer that erases the specific io::Write and MakeWriter types being used.

This is useful in cases where the concrete type of the writer cannot be known until runtime.

Examples

A function that returns a Subscriber that will write to either stdout or stderr:

fn dynamic_writer(use_stderr: bool) -> impl Subscriber {
    let writer = if use_stderr {
        BoxMakeWriter::new(std::io::stderr)
    } else {
        BoxMakeWriter::new(std::io::stdout)
    };

    tracing_subscriber::fmt().with_writer(writer).finish()
}

Implementations

impl BoxMakeWriter

pub fn new<M>(make_writer: M) -> Self

where M: for<'a> MakeWriter<'a> + Send + Sync + 'static,

Constructs a BoxMakeWriter wrapping a type implementing MakeWriter.

Trait Implementations

impl Debug for BoxMakeWriter

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

Formats the value using the given formatter.

impl<'a> MakeWriter<'a> for BoxMakeWriter

type Writer = Box<dyn Write + 'a>

The concrete io::Write implementation returned by make_writer.

fn make_writer(&'a self) -> Self::Writer

Returns an instance of Writer.

fn make_writer_for(&'a self, meta: &Metadata<'_>) -> Self::Writer

Returns a Writer for writing data from the span or event described by the provided Metadata.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 32 bytes