Struct SimpleLogger

pub struct SimpleLogger {
    pub(crate) default_level: LevelFilter,
    pub(crate) module_levels: Vec<(String, LevelFilter)>,
    pub(crate) timestamps: Timestamps,
    pub(crate) timestamps_format: Option<&'static [FormatItem<'static>]>,
    pub(crate) colors: bool,
}

Implements Log and a set of simple builder methods for configuration.

Use the various “builder” methods on this struct to configure the logger, then call init to configure the log crate.

Fields

default_level: LevelFilter

The default logging level

module_levels: Vec<(String, LevelFilter)>

The specific logging level for each module

This is used to override the default value for some specific modules.

This must be sorted from most-specific to least-specific, so that enabled can scan the vector for the first match to give us the desired log level for a module.

timestamps: Timestamps

Control how timestamps are displayed.

This field is only available if the timestamps feature is enabled.

timestamps_format: Option<&'static [FormatItem<'static>]>

colors: bool

Whether to use color output or not.

This field is only available if the color feature is enabled.

Implementations

impl SimpleLogger

pub fn new() -> SimpleLogger

Initializes the global logger with a SimpleLogger instance with default log level set to Level::Trace.

use simple_logger::SimpleLogger;
SimpleLogger::new().env().init().unwrap();
log::warn!("This is an example message.");

pub fn from_env() -> SimpleLogger

👎Deprecated since 1.12.0: Use env instead. Will be removed in version 2.0.0.

Initializes the global logger with log level read from RUST_LOG environment variable value. Deprecated in favor of env().

You may use the various builder-style methods on this type to configure the logger, and you must call init in order to start logging messages.

use simple_logger::SimpleLogger;
SimpleLogger::from_env().init().unwrap();
log::warn!("This is an example message.");

pub fn env(self) -> SimpleLogger

Enables the user to choose log level by setting RUST_LOG=<level> environment variable. This will use the default level set by with_level if RUST_LOG is not set or can’t be parsed as a standard log level.

This must be called after with_level. If called before with_level, it will have no effect.

pub fn with_level(self, level: LevelFilter) -> SimpleLogger

Set the ‘default’ log level.

You can override the default level for specific modules and their sub-modules using with_module_level

This must be called before env. If called after env, it will override the value loaded from the environment.

pub fn with_module_level(self, target: &str, level: LevelFilter) -> SimpleLogger

Override the log level for some specific modules.

This sets the log level of a specific module and all its sub-modules. When both the level for a parent module as well as a child module are set, the more specific value is taken. If the log level for the same module is specified twice, the resulting log level is implementation defined.

Examples

Silence an overly verbose crate:

use simple_logger::SimpleLogger;
use log::LevelFilter;

SimpleLogger::new().with_module_level("chatty_dependency", LevelFilter::Warn).init().unwrap();

Disable logging for all dependencies:

use simple_logger::SimpleLogger;
use log::LevelFilter;

SimpleLogger::new()
    .with_level(LevelFilter::Off)
    .with_module_level("my_crate", LevelFilter::Info)
    .init()
    .unwrap();

pub fn with_target_levels( self, target_levels: HashMap<String, LevelFilter>, ) -> SimpleLogger

👎Deprecated since 1.11.0: Use with_module_level instead. Will be removed in version 2.0.0.

Override the log level for specific targets.

pub fn with_timestamps(self, timestamps: bool) -> SimpleLogger

👎Deprecated since 1.16.0: Use [with_local_timestamps] or [with_utc_timestamps] instead. Will be removed in version 2.0.0.

Control whether timestamps are printed or not.

Timestamps will be displayed in the local timezone.

This method is only available if the timestamps feature is enabled.

pub fn with_timestamp_format( self, format: &'static [FormatItem<'static>], ) -> SimpleLogger

Control the format used for timestamps.

Without this, a default format is used depending on the timestamps type.

The syntax for the format_description macro can be found in the time crate book.

simple_logger::SimpleLogger::new()
 .with_level(log::LevelFilter::Debug)
 .env()
 .with_timestamp_format(time::macros::format_description!("[year]-[month]-[day] [hour]:[minute]:[second]"))
 .init()
 .unwrap();

pub fn without_timestamps(self) -> SimpleLogger

Don’t display any timestamps.

This method is only available if the timestamps feature is enabled.

pub fn with_local_timestamps(self) -> SimpleLogger

Display timestamps using the local timezone.

This method is only available if the timestamps feature is enabled.

pub fn with_utc_timestamps(self) -> SimpleLogger

Display timestamps using UTC.

This method is only available if the timestamps feature is enabled.

pub fn with_utc_offset(self, offset: UtcOffset) -> SimpleLogger

Display timestamps using a static UTC offset.

This method is only available if the timestamps feature is enabled.

pub fn with_colors(self, colors: bool) -> SimpleLogger

Control whether messages are colored or not.

This method is only available if the colored feature is enabled.

pub fn max_level(&self) -> LevelFilter

Configure the logger

pub fn init(self) -> Result<(), SetLoggerError>

‘Init’ the actual logger and instantiate it, this method MUST be called in order for the logger to be effective.

Trait Implementations

impl Default for SimpleLogger

fn default() -> Self

See this

impl Log for SimpleLogger

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.