Documentation

Logger is just a name.

Level also known as severity, a higher Level means a bigger Int.

A LogRecord represents an event being logged.

LogRecords are created every time something is logged. They contain all the information related to the event being logged.

It includes the main message as well as information such as when the record was created, the source line where the logging call was made.

Filters are used to perform arbitrary filtering of LogRecords.

Sinks and Handlers can optionally use Filter to filter records as desired. It allows events which are below a certain point in the sink hierarchy. For example, a filter initialized with A.B will allow events logged by loggers A.B, A.B.C, A.B.C.D, A.B.D etc. but not A.BB, B.A.B etc. If initialized name with the empty string, all events are passed.

List of Filter

Formatters are used to convert a LogRecord to text.

Formatters need to know how a LogRecord is constructed. They are responsible for converting a LogRecord to (usually) a string which can be interpreted by either a human or an external system. The base Formatter allows a formatting string to be specified. If none is supplied, the default value, "%(message)s" is used.

The Formatter can be initialized with a format string which makes use of knowledge of the LogRecord attributes - e.g. the default value mentioned above makes use of a LogRecord's message attribute. Currently, the useful attributes in a LogRecord are described by:

%(logger)s

Name of the logger (logging channel)

%(level)s

Numeric logging level for the message (DEBUG, INFO, WARN, ERROR, FATAL, LEVEL v)

%(pathname)s

Full pathname of the source file where the logging call was issued (if available)

%(filename)s

Filename portion of pathname

%(module)s

Module (name portion of filename)

%(lineno)d

Source line number where the logging call was issued (if available)

%(created)f

Time when the LogRecord was created (picoseconds since '1970-01-01 00:00:00')

%(asctime)s

Textual time when the LogRecord was created

%(msecs)d

Millisecond portion of the creation time

%(message)s

The main message passed to logv debug info ..

A handler type which writes logging records, appropriately formatted, to a stream.

Note that this class does not close the stream when the stream is a terminal device, e.g. stderr and stdout.

Note: FileHandler is an alias of StreamHandler

A GADT represents any Handler instance

Sink represents a single logging channel.

A "logging channel" indicates an area of an application. Exactly how an "area" is defined is up to the application developer. Since an application can have any number of areas, logging channels are identified by a unique string. Application areas can be nested (e.g. an area of "input processing" might include sub-areas "read CSV files", "read XLS files" and "read Gnumeric files"). To cater for this natural nesting, channel names are organized into a namespace hierarchy where levels are separated by periods, much like the Haskell module namespace. So in the instance given above, channel names might be Input for the upper level, and Input.Csv, Input.Xls and Input.Gnu for the sub-levels. There is no arbitrary limit to the depth of nesting.

Note: The namespaces are case sensitive.

There is under normal circumstances just one Manager, which holds the hierarchy of sinks.

A class represents a common trait of filtering LogRecords

A class represents a common trait of formatting LogRecord as String.

A type class that abstracts the characteristics of a Handler