Struct Metadata

pub struct Metadata<'a> {
    pub(crate) level: Level,
    pub(crate) target: &'a str,
}

Metadata about a log message.

Use

Metadata structs are created when users of the library use logging macros.

They are consumed by implementations of the Log trait in the enabled method.

Records use Metadata to determine the log message’s severity and target.

Users should use the log_enabled! macro in their code to avoid constructing expensive log messages.

Examples

use log::{Record, Level, Metadata};

struct MyLogger;

impl log::Log for MyLogger {
    fn enabled(&self, metadata: &Metadata) -> bool {
        metadata.level() <= Level::Info
    }

    fn log(&self, record: &Record) {
        if self.enabled(record.metadata()) {
            println!("{} - {}", record.level(), record.args());
        }
    }
    fn flush(&self) {}
}

Fields

level: Level

target: &'a str

Implementations

impl<'a> Metadata<'a>

pub fn builder() -> MetadataBuilder<'a>

Returns a new builder.

pub fn level(&self) -> Level

The verbosity level of the message.

pub fn target(&self) -> &'a str

The name of the target of the directive.

Trait Implementations

impl<'a> Clone for Metadata<'a>

fn clone(&self) -> Metadata<'a>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'a> Debug for Metadata<'a>

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

Formats the value using the given formatter.

impl<'a> Hash for Metadata<'a>

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

where __H: Hasher,

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<'a> Ord for Metadata<'a>

fn cmp(&self, other: &Metadata<'a>) -> 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<'a> PartialEq for Metadata<'a>

fn eq(&self, other: &Metadata<'a>) -> 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> PartialOrd for Metadata<'a>

fn partial_cmp(&self, other: &Metadata<'a>) -> 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<'a> Eq for Metadata<'a>

impl<'a> StructuralPartialEq for Metadata<'a>