Module logi_layout

Description
Data Types
Function Index
Function Details

Log Message Layout Behaviour.

This module defines the logi_layout behaviour.
Required callback functions: format/4.

Description

Log Message Layout Behaviour

This module defines the standard interface to format log messages issued by logi functions (e.g. logi:info/3, logi:warning/3, etc).

A layout instance may be installed into a channel along with an associated sink.

EXAMPLE

Usage example of a layout instance:

  > error_logger:tty(false). % Suppresses annoying warning outputs for brevity
 
  > Context = logi_context:new(sample_log, info).
  > FormatFun = fun (_, Format, Data) -> lists:flatten(io_lib:format("EXAMPLE: " ++ Format, Data)) end.
  > Layout = logi_builtin_layout_fun:new(FormatFun).
  > logi_layout:format(Context, "Hello ~s", ["World"], Layout).
  "EXAMPLE: Hello World"

A more realistic example:

  > FormatFun = fun (_, Format, Data) -> lists:flatten(io_lib:format("EXAMPLE: " ++ Format ++ "\n", Data)) end.
  > Layout = logi_builtin_layout_fun:new(FormatFun).
  > {ok, _} = logi_channel:install_sink(logi_builtin_sink_io_device:new(foo, [{layout, Layout}]), info).
  > logi:info("hello world").
  EXAMPLE: hello world

Data Types

callback_module()

callback_module() = module()

A module that implements the logi_layout behaviour.

data()

data() = [term()]

A data which is subject to format

This type is an alias of the type of second arguemnt of the io_lib:format/2

extra_data()

extra_data() = term()

The value of the fourth arguemnt of the format/4 callback function.

If the layout() does not have an explicit extra_data(), undefined will be passed instead.

formatted_data()

formatted_data() = term()

Formatted Data

layout()

abstract datatype: layout(_FormattedData)

An instance of logi_layout behaviour implementation module.

layout()

layout() = layout(formatted_data())

An instance of logi_layout behaviour implementation module.

Function Index

format/4	Returns an `iodata()` which represents `Data` formatted by `Layout` in accordance with `Format` and `Context`
get_extra_data/1	Gets the extra data of `Layout`
get_module/1	Gets the module of `Layout`
is_layout/1	Returns `true` if `X` is a layout, `false` otherwise.
new/1	Equivalent to `new(Module, undefined)`.
new/2	Creates a new layout instance.