class Logger
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
.
If logging to multiple locations is required, an IO::MultiWriter
can be
used.
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
Defined in:
logger.crConstant Summary
-
DEBUG =
Severity::DEBUG
-
ERROR =
Severity::ERROR
-
FATAL =
Severity::FATAL
-
INFO =
Severity::INFO
-
UNKNOWN =
Severity::UNKNOWN
-
WARN =
Severity::WARN
Constructors
-
.new(io : IO?, level = Severity::INFO, formatter = DEFAULT_FORMATTER, progname = "")
Creates a new logger that will log to the given io.
Instance Method Summary
-
#close
Calls the close method on the object passed to
initialize
. -
#debug(progname = nil, &block)
Logs the message as returned from the given block if the logger's current severity is lower or equal to
DEBUG
. -
#debug(message, progname = nil)
Logs message if the logger's current severity is lower or equal to
DEBUG
. -
#debug?
Returns
true
if the logger's current severity is lower or equal toDEBUG
. -
#error(progname = nil, &block)
Logs the message as returned from the given block if the logger's current severity is lower or equal to
ERROR
. -
#error(message, progname = nil)
Logs message if the logger's current severity is lower or equal to
ERROR
. -
#error?
Returns
true
if the logger's current severity is lower or equal toERROR
. -
#fatal(progname = nil, &block)
Logs the message as returned from the given block if the logger's current severity is lower or equal to
FATAL
. -
#fatal(message, progname = nil)
Logs message if the logger's current severity is lower or equal to
FATAL
. -
#fatal?
Returns
true
if the logger's current severity is lower or equal toFATAL
. - #formatter : Logger::Severity, Time, String, String, IO -> Nil
- #formatter=(formatter)
-
#info(message, progname = nil)
Logs message if the logger's current severity is lower or equal to
INFO
. -
#info(progname = nil, &block)
Logs the message as returned from the given block if the logger's current severity is lower or equal to
INFO
. -
#info?
Returns
true
if the logger's current severity is lower or equal toINFO
. - #level : Severity
- #level=(level : Severity)
-
#log(severity, message, progname = nil)
Logs message if severity is higher or equal with the logger's current severity.
-
#log(severity, progname = nil, &block)
Logs the message as returned from the given block if severity is higher or equal with the loggers current severity.
- #progname : String
- #progname=(progname : String)
-
#unknown(message, progname = nil)
Logs message if the logger's current severity is lower or equal to
UNKNOWN
. -
#unknown(progname = nil, &block)
Logs the message as returned from the given block if the logger's current severity is lower or equal to
UNKNOWN
. -
#unknown?
Returns
true
if the logger's current severity is lower or equal toUNKNOWN
. -
#warn(progname = nil, &block)
Logs the message as returned from the given block if the logger's current severity is lower or equal to
WARN
. -
#warn(message, progname = nil)
Logs message if the logger's current severity is lower or equal to
WARN
. -
#warn?
Returns
true
if the logger's current severity is lower or equal toWARN
.
Instance methods inherited from class Reference
==(other : self)==(other : JSON::Any)
==(other : YAML::Any)
==(other) ==, dup dup, hash(hasher) hash, inspect(io : IO) : Nil inspect, object_id : UInt64 object_id, pretty_print(pp) : Nil pretty_print, same?(other : Reference)
same?(other : Nil) same?, to_s(io : IO) : Nil to_s
Constructor methods inherited from class Reference
new
new
Instance methods inherited from class Object
!=(other)
!=,
!~(other)
!~,
==(other)
==,
===(other : JSON::Any)===(other : YAML::Any)
===(other) ===, =~(other) =~, class class, dup dup, hash(hasher)
hash hash, inspect(io : IO)
inspect inspect, itself itself, not_nil! not_nil!, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, tap(&block) tap, to_json(io : IO)
to_json to_json, to_pretty_json(indent : String = " ")
to_pretty_json(io : IO, indent : String = " ") to_pretty_json, to_s
to_s(io : IO) to_s, to_yaml(io : IO)
to_yaml to_yaml, try(&block) try, unsafe_as(type : T.class) forall T unsafe_as
Constructor methods inherited from class Object
from_json(string_or_io, root : String) : selffrom_json(string_or_io) : self from_json, from_yaml(string_or_io : String | IO) : self from_yaml
Constructor Detail
Creates a new logger that will log to the given io.
If io is nil
then all log calls will be silently ignored.
Instance Method Detail
Logs the message as returned from the given block if the logger's current severity
is lower or equal to DEBUG
. The block is not run if the severity is higher.
progname overrides a default progname set in this logger.
Logs message if the logger's current severity is lower or equal to DEBUG
.
progname overrides a default progname set in this logger.
Logs the message as returned from the given block if the logger's current severity
is lower or equal to ERROR
. The block is not run if the severity is higher.
progname overrides a default progname set in this logger.
Logs message if the logger's current severity is lower or equal to ERROR
.
progname overrides a default progname set in this logger.
Logs the message as returned from the given block if the logger's current severity
is lower or equal to FATAL
. The block is not run if the severity is higher.
progname overrides a default progname set in this logger.
Logs message if the logger's current severity is lower or equal to FATAL
.
progname overrides a default progname set in this logger.
Customizable Proc
(with a reasonable default)
which the Logger
uses to format and print its entries.
Use this setter to provide a custom formatter.
The Logger
will invoke it with the following arguments:
- severity: a
Logger::Severity
- datetime:
Time
, the entry's timestamp - progname:
String
, the program name, if set when the logger was built - message:
String
, the body of a message - io:
IO
, the Logger's stream, to which you must write the final output
Example:
require "logger"
logger = Logger.new(STDOUT)
logger.progname = "YodaBot"
logger.formatter = Logger::Formatter.new do |severity, datetime, progname, message, io|
label = severity.unknown? ? "ANY" : severity.to_s
io << label[0] << ", [" << datetime << " #" << Process.pid << "] "
io << label.rjust(5) << " -- " << progname << ": " << message
end
logger.warn("Fear leads to anger. Anger leads to hate. Hate leads to suffering.")
# Prints to the console:
# "W, [2017-05-06 18:00:41 -0300 #11927] WARN --
# YodaBot: Fear leads to anger. Anger leads to hate. Hate leads to suffering."
Customizable Proc
(with a reasonable default)
which the Logger
uses to format and print its entries.
Use this setter to provide a custom formatter.
The Logger
will invoke it with the following arguments:
- severity: a
Logger::Severity
- datetime:
Time
, the entry's timestamp - progname:
String
, the program name, if set when the logger was built - message:
String
, the body of a message - io:
IO
, the Logger's stream, to which you must write the final output
Example:
require "logger"
logger = Logger.new(STDOUT)
logger.progname = "YodaBot"
logger.formatter = Logger::Formatter.new do |severity, datetime, progname, message, io|
label = severity.unknown? ? "ANY" : severity.to_s
io << label[0] << ", [" << datetime << " #" << Process.pid << "] "
io << label.rjust(5) << " -- " << progname << ": " << message
end
logger.warn("Fear leads to anger. Anger leads to hate. Hate leads to suffering.")
# Prints to the console:
# "W, [2017-05-06 18:00:41 -0300 #11927] WARN --
# YodaBot: Fear leads to anger. Anger leads to hate. Hate leads to suffering."
Logs message if the logger's current severity is lower or equal to INFO
.
progname overrides a default progname set in this logger.
Logs the message as returned from the given block if the logger's current severity
is lower or equal to INFO
. The block is not run if the severity is higher.
progname overrides a default progname set in this logger.
Logs message if severity is higher or equal with the logger's current severity. progname overrides a default progname set in this logger.
Logs the message as returned from the given block if severity is higher or equal with the loggers current severity. The block is not run if severity is lower. progname overrides a default progname set in this logger.
Logs message if the logger's current severity is lower or equal to UNKNOWN
.
progname overrides a default progname set in this logger.
Logs the message as returned from the given block if the logger's current severity
is lower or equal to UNKNOWN
. The block is not run if the severity is higher.
progname overrides a default progname set in this logger.
Logs the message as returned from the given block if the logger's current severity
is lower or equal to WARN
. The block is not run if the severity is higher.
progname overrides a default progname set in this logger.