The Logger
class is the primary interface to the
Logging
framework. It provides the logging methods that will
be called from user methods, and it generates logging events that are sent
to the appenders (the appenders take care of sending the log events to the
logging destinations -- files, sockets, etc).
Logger
instances are obtained from the Repository
and should not be directly created by users.
Example:
log = Logging.logger['my logger'] log.add_appenders( Logging.appenders.stdout ) # append to STDOUT log.level = :info # log 'info' and above log.info 'starting foo operation' ... log.info 'finishing foo operation' ... log.fatal 'unknown exception', exception
Returns the logger identified by name.
When name is a String
or a Symbol
it
will be used "as is" to retrieve the logger. When name is a
Class
the class name will be used to retrieve the logger. When
name is an object the name of the object's class will be used to
retrieve the logger.
Example:
obj = MyClass.new log1 = Logger.new(obj) log2 = Logger.new(MyClass) log3 = Logger['MyClass'] log1.object_id == log2.object_id # => true log2.object_id == log3.object_id # => true
# File lib/logging/logger.rb, line 151 def initialize( name ) case name when String raise(ArgumentError, "logger must have a name") if name.empty? else raise(ArgumentError, "logger name must be a String") end repo = ::Logging::Repository.instance _setup(name, :parent => repo.parent(name)) end
Returns the root logger.
# File lib/logging/logger.rb, line 36 def root ::Logging::Repository.instance[:root] end
Log the given message without any formatting and without performing any
level checks. The message is logged to all appenders. The message is passed
up the logger tree if this logger's additivity is true
.
# File lib/logging/logger.rb, line 182 def <<( msg ) @appenders.each {|a| a << msg} @parent << msg if @additive end
Compares this logger by name to another logger. The normal return codes for
String
objects apply.
# File lib/logging/logger.rb, line 167 def <=>( other ) case other when self; 0 when ::Logging::RootLogger; 1 when ::Logging::Logger; @name <=> other.name else raise ArgumentError, 'expecting a Logger instance' end end
Log a message if the given severity is high enough. This is the generic logging method. Users will be more inclined to use debug, info, warn, error, and fatal.
Message format: message
can be any object,
but it has to be converted to a String in
order to log it. The Logging.format_as method is
used to determine how objects chould be converted to strings. Generally,
inspect
is used.
A special case is an Exception
object, which will be printed
in detail, including message, class, and backtrace.
If a message is not given, then the return value from the block is used as the message to log. This is useful when creating the actual message is an expensive operation. This allows the logger to check the severity against the configured level before actually constructing the message.
This method returns true
if the message was logged, and
false
is returned if the message was not logged.
# File lib/logging/logger.rb, line 212 def add( lvl, data = nil, progname = nil ) lvl = Integer(lvl) return false if lvl < level data = yield if block_given? log_event(::Logging::LogEvent.new(@name, lvl, data, @trace)) true end
Add the given appenders to the list of appenders, where appenders can be either a single appender or an array of appenders.
# File lib/logging/logger.rb, line 333 def add_appenders( *args ) args.flatten.each do |arg| o = arg.kind_of?(::Logging::Appender) ? arg : ::Logging::Appenders[arg.to_s] raise ArgumentError, "unknown appender #{arg.inspect}" if o.nil? @appenders << o unless @appenders.include?(o) end self end
Sets the additivity of the logger. Acceptable values are true
,
'true', false
, 'false', or nil
. In this case
nil
does not change the additivity
# File lib/logging/logger.rb, line 228 def additive=( val ) @additive = case val when true, 'true'; true when false, 'false'; false when nil; @additive else raise ArgumentError, 'expecting a boolean' end end
Returns the list of appenders.
# File lib/logging/logger.rb, line 312 def appenders @appenders.dup end
Clears the current list of appenders and replaces them with app, where app can be either a single appender or an array of appenders.
# File lib/logging/logger.rb, line 322 def appenders=( args ) @appenders.clear add_appenders(*args) unless args.nil? end
Remove all appenders from this logger.
# File lib/logging/logger.rb, line 369 def clear_appenders( ) @appenders.clear end
Returns a string representation of the logger.
# File lib/logging/logger.rb, line 376 def inspect "<%s:0x%x name=\"%s\">" % [self.class.name, self.object_id, self.name] end
Returns an integer which is the defined log level for this logger.
# File lib/logging/logger.rb, line 256 def level return @level unless @level.nil? @parent.level end
Set the level for this logger. The level can be either a
String
, a Symbol
, or a Fixnum
. An
ArgumentError
is raised if this is not the case.
There are two special levels -- "all" and "off". The former will enable log messages from this logger. The latter will disable all log messages from this logger.
Setting the logger level to nil
will cause the parent's logger
level to be used.
Example:
log.level = :debug log.level = "INFO" log.level = 4 log.level = 'off' log.level = :all
These produce an ArgumentError
log.level = Object log.level = -1 log.level = 1_000_000_000_000
# File lib/logging/logger.rb, line 289 def level=( level ) @level = if level.nil? then level else lvl = case level when String, Symbol; ::Logging::level_num(level) when Fixnum; level else raise ArgumentError, "level must be a String, Symbol, or Integer" end if lvl.nil? or lvl < 0 or lvl > ::Logging::LEVELS.length raise ArgumentError, "unknown level was given '#{level}'" end lvl end define_log_methods(true) self.level end
Remove the given appenders from the list of appenders. The
appenders to remove can be identified either by name using a
String
or by passing the appender instance. appenders
can be a single appender or an array of appenders.
# File lib/logging/logger.rb, line 350 def remove_appenders( *args ) args.flatten.each do |arg| @appenders.delete_if do |a| case arg when String; arg == a.name when ::Logging::Appender; arg.object_id == a.object_id else raise ArgumentError, "#{arg.inspect} is not a 'Logging::Appender'" end end end self end
Sets the tracing of the logger. Acceptable values are true
,
'true', false
, 'false', or nil
. In this case
nil
does not change the tracing.
# File lib/logging/logger.rb, line 243 def trace=( val ) @trace = case val when true, 'true'; true when false, 'false'; false when nil; @trace else raise ArgumentError, 'expecting a boolean' end end
Define the logging methods for this logger based on the configured log level. If the level is nil, then we will ask our parent for it's level and define log levels accordingly. The force flag will skip this check.
Recursively call this method on all our children loggers.
# File lib/logging/logger.rb, line 414 def define_log_methods( force = false ) return if @level and !force ::Logging::Logger.define_log_methods(self) ::Logging::Repository.instance.children(name).each do |c| c.define_log_methods end self end
Send the given event to the appenders for logging, and pass the event up to the parent if additive mode is enabled. The log level has already been checked before this method is called.
# File lib/logging/logger.rb, line 399 def log_event( event ) @appenders.each {|a| a.append(event)} @parent.log_event(event) if @additive end
Set the parent logger for this logger. This method will be invoked by the
Repository
class when a parent or child is added to the
hierarchy.
# File lib/logging/logger.rb, line 390 def parent=( parent ) @parent = parent end