Struct Logger

pub struct Logger {
    writer: Writer,
    filter: Filter,
    format: Box<dyn Fn(&mut Formatter, &Record<'_>) -> Result<()> + Sync + Send>,
}

The env logger.

This struct implements the Log trait from the log crate, which allows it to act as a logger.

The init(), try_init(), Builder::init() and Builder::try_init() methods will each construct a Logger and immediately initialize it as the default global logger.

If you’d instead need access to the constructed Logger, you can use the associated Builder and install it with the log crate directly.

Fields

writer: Writer

filter: Filter

format: Box<dyn Fn(&mut Formatter, &Record<'_>) -> Result<()> + Sync + Send>

Implementations

impl Logger

pub fn from_env<'a, E>(env: E) -> Self

where E: Into<Env<'a>>,

Creates the logger from the environment.

The variables used to read configuration from can be tweaked before passing in.

Examples

Create a logger reading the log filter from an environment variable called MY_LOG:

use env_logger::Logger;

let logger = Logger::from_env("MY_LOG");

Create a logger using the MY_LOG variable for filtering and MY_LOG_STYLE for whether or not to write styles:

use env_logger::{Logger, Env};

let env = Env::new().filter_or("MY_LOG", "info").write_style_or("MY_LOG_STYLE", "always");

let logger = Logger::from_env(env);

pub fn from_default_env() -> Self

Creates the logger from the environment using default variable names.

This method is a convenient way to call from_env(Env::default()) without having to use the Env type explicitly. The logger will use the default environment variables.

Examples

Creates a logger using the default environment variables:

use env_logger::Logger;

let logger = Logger::from_default_env();

pub fn filter(&self) -> LevelFilter

Returns the maximum LevelFilter that this env logger instance is configured to output.

pub fn matches(&self, record: &Record<'_>) -> bool

Checks if this record matches the configured filter.

Trait Implementations

impl Debug for Logger

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

Formats the value using the given formatter.

impl Log for Logger

fn enabled(&self, metadata: &Metadata<'_>) -> bool

Determines if a log message with the specified metadata would be logged.

fn log(&self, record: &Record<'_>)

Logs the Record.

fn flush(&self)

Flushes any buffered records.