Struct tracing_subscriber::fmt::writer::BoxMakeWriter

pub struct BoxMakeWriter { /* fields omitted */ }

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: MakeWriter + Send + Sync + 'static,
    M::Writer: Write + '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 MakeWriter for BoxMakeWriter

type Writer = Box<dyn Write>

The concrete io::Write implementation returned by make_writer.

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

Returns an instance of Writer.

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

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