logger

Provides the legacy Logger functionality.

Installation

1. Add the dependency to your shard.yml:

   dependencies:
     logger:
       github: crystal-lang/logger.cr

2. Run shards install

Usage

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 or 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

# or
log = Logger.new(STDOUT, level: Logger::WARN)

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

begin
  File.each_line("/foo/bar.log") 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

If logging to multiple locations is required, an IO::MultiWriter can be used.

file = File.new("production.log", "a")
writer = IO::MultiWriter.new(file, STDOUT)

log = Logger.new(writer)
log.level = Logger::DEBUG
log.debug("Created logger")

Contributing

1. Fork it (https://github.com/crystal-lang/logger.cr/fork)
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request