class Logger(T)

Overview

The Logger class provides a simple but sophisticated logging utility that you can use to output messages.

The messages have associated levels, such as INFO or ERROR that indicate their importance. You can then give the Logger a level, and only messages at that level of higher will be printed.

For instance, in a production system, you may have your Logger set to INFO or even WARN. When you are developing the system, however, you probably want to know about the program’s internal state, and would set the Logger to DEBUG.

Example

require "logger"

log = Logger.new(STDOUT)
log.level = Logger::WARN

log.debug("Created logger")
log.info("Program started")
log.warn("Nothing to do!")

begin
  File.each_line(path) do |line|
    unless line =~ /^(\\w+) = (.*)$/
      log.error("Line in wrong format: #{line}")
    end
  end
rescue err
  log.fatal("Caught exception; exiting")
  log.fatal(err)
end

Superclass hierarchy

Defined in:

Constant Summary

• DEBUG = Severity::DEBUG
• ERROR = Severity::ERROR
• FATAL = Severity::FATAL
• INFO = Severity::INFO
• UNKNOWN = Severity::UNKNOWN
• WARN = Severity::WARN

Class Method Summary

• .new(io : T)

Instance Method Summary

• #<<(message)
• #close
• #debug(progname = nil, &block)
• #debug(message, progname = nil)
• #debug?
• #error(progname = nil, &block)
• #error(message, progname = nil)
• #error?
• #fatal(message, progname = nil)
• #fatal(progname = nil, &block)
• #fatal?
• #format(severity, datetime, progname, message, io)
• #formatter
• #formatter=(formatter)
• #info(message, progname = nil)
• #info(progname = nil, &block)
• #info?
• #level
• #level=(level)
• #log(severity, message, progname = nil)
• #log(severity, progname = nil, &block)
• #progname
• #progname=(progname)
• #unknown(progname = nil, &block)
• #unknown(message, progname = nil)
• #unknown?
• #warn(message, progname = nil)
• #warn(progname = nil, &block)
• #warn?

Macro Summary

• log_level(name)

Class Method Detail

Instance Method Detail

Macro Detail