Method: Logger#formatter

Defined in:

lib/logger.rb

#formatter ⇒ Object

Sets or retrieves the logger entry formatter proc.

When formatter is nil, the logger uses Logger::Formatter.

When formatter is a proc, a new entry is formatted by the proc, which is called with four arguments:

• severity: The severity of the entry.

• time: A Time object representing the entry’s timestamp.

• progname: The program name for the entry.

• msg: The message for the entry (string or string-convertible object).

The proc should return a string containing the formatted entry.

This custom formatter uses String#dump to escape the message string:

logger = Logger.new($stdout, progname: 'mung')
original_formatter = logger.formatter || Logger::Formatter.new
logger.formatter = proc { |severity, time, progname, msg|
  original_formatter.call(severity, time, progname, msg.dump)
}
logger.add(Logger::INFO, "hello \n ''")
logger.add(Logger::INFO, "\f\x00\xff\\\"")

Output:

I, [2022-05-13T13:16:29.637488 #8492]  INFO -- mung: "hello \n ''"
I, [2022-05-13T13:16:29.637610 #8492]  INFO -- mung: "\f\x00\xFF\\\""

# File 'lib/logger.rb', line 473

def formatter
  @formatter
end