Logger

Module	ejs
Definition	class Logger
Inheritance	Logger Object
Specified	ejscript-2.5
Stability	Prototype.

Logger objects provide a convenient and consistent method to capture and store logging information.

Loggers can direct output to Streams and may be aggregated in a hierarchical manner. The verbosity of logging can be managed and messages can be filtered.

Hierarchies of loggers can be constructed by specifying a parent logger when creating a logger instance. For example, a logger can be created for each class in a package with all such loggers having a single parent. Loggers can send log messages to their parent and inherit their parent's log level. The top level logger for an application is defined by App.log.

Each logger may define a filter function that returns true or false depending on whether a specific message should be logged or not. A matching pattern can alternatively be used to filter messages.

An Application will have a default Logger instance created and stored in App.log at startup. This Logger uses the LogFile class to communicate with the Application's native log file. This is typically initialized by the "--log" command line switch and otherwise defaults to send messages to the standard error console.

Properties

Qualifiers	Property	Type	Description
static const	All	Number	Logging level to output all messages.
static const	Config	Number	Logging level for configuration output.
static const	Error	Number	Logging level for most serious errors. (.
static const	Info	Number	Logging level for informational messages.
static const	Off	Number	Logging level for no logging.
static const	Warn	Number	Logging level for warnings.
get set	filter	Function	Filter function for this logger. The filter function is called with the following signature: with "this" set to the Logger instance. The log parameter is set to the original logger that created the message. function filter(log: Logger, name: String, level: Number, kind: String, msg: String): Boolean.
get set	level	Number	The numeric verbosity setting (0-9) of this logger. Zero is least verbose, nine is the most verbose. Messages with a lower (or equal) verbosity level than the logger's level are emitted. (.
get	location		The logging location parameter specified when constructing or redirecting the logger.
get set	match	RegExp	Matching expression to filter log messages. The match regular expression is used to match against the Logger names.
get set	name	String	The name of this logger.
get set	outStream	Stream	The output stream used by the logger.

Inherited Properties

Logger Class Methods

(No own class methods defined)

Qualifiers	Method

Inherited Methods

Logger Instance Methods

Qualifiers	Method
	Logger(name: String, location, level: Number = 0)
	Logger constructor.
	close(): Void
	Close the logger.
	config(msgs: Array): Void
	Emit a configuration message.
	debug(level: Number, msgs: Array): Void
	Emit a debug message.
	error(msgs: Array): Void
	Emit an error message.
	info(msgs: Array): Void
	Emit an informational message.
	redirect(location, level: Number = null): Void
	Redirect log output.
	warn(msgs: Array): Void
	Emit a warning message.
	write(data: Array): Number
	Write data to the stream.Write messages to the logger stream.

Inherited Methods

Method Detail

Logger(name: String, location, level: Number = 0)

Description: Logger constructor. The Logger constructor can create different types of loggers based on the three (optional) arguments.

Parameters

name: String	Unique name of the logger. Loggers are typically named after the module, class or subsystem they are associated with.
location	Optional output stream or Logger to send messages to. If a parent Logger instance is provided for the output parameter, messages are sent to the parent for rendering.
level: Number	Optional integer verbosity level. Messages with a message level less than or equal to the defined logger level will be emitted. Range is 0 (least verbose) to 9. [default: 0]

Example

var file = File("progress.log", "w")
var log = new Logger("name", file, 5)
log.debug(2, "message")

close(): Void

Description: Close the logger.

config(msgs: Array): Void

Description: Emit a configuration message.

Parameters

msgs: Array

Data to log.

debug(level: Number, msgs: Array): Void

Description: Emit a debug message. The message level will be compared to the logger setting to determine whether it will be output to the devices or not. Also, if the logger has a filter function set that may filter the message out before logging.

Parameters

level: Number	The level of the message.
msgs: Array	The string message to log.

error(msgs: Array): Void

Description: Emit an error message.

Parameters

msgs: Array

Data to log.

info(msgs: Array): Void

Description: Emit an informational message.

Parameters

msgs: Array

Data to log.

redirect(location, level: Number = null): Void

Description: Redirect log output.

Parameters

location	Optional output stream, Logger or location specification to send messages to. If a parent Logger instance is provided, messages are sent to the parent for rendering. A location specification is of the form: file:level.
level: Number	Optional integer verbosity level. Messages with a message level less than or equal to the defined logger level will be emitted. Range is 0 (least verbose) to 9. H. [default: null]

warn(msgs: Array): Void

Description: Emit a warning message.

Parameters

msgs: Array

The data to log.

write(data: Array): Number

Description: Write data to the stream.Write messages to the logger stream. If the stream can accept all the write data, the call returns immediately with the number of bytes written. If writing more data than the stream can absorb in sync mode, the call will block until the data is written. If writing more data than the stream can absorb in async mode, the call will not block and will buffer the data and return immediately. Some streams will require a flush() call to actually send the data. A "writable" event will be issued when the stream can again absorb more data.NOTE: for the Logger class, I/O errors will not throw exceptions.

Parameters

data: Array

Data to write.

Events

readable	Issued when data is written and a consumer can read without blocking.
writable	Issued when the stream becomes empty and it is ready to be written to.

Returns: A count of the bytes actually written.

Throws: IOError: if there is an I/O error.