log

Common usage

local log = require("log")
local info = log.new()

info:print("ok", " ", 1.2)
-- ok 1.2

info:println("ok", 1.2)
-- ok 1.2

info:printf("%s %f", "ok", 1.2)
-- ok 1.2

Set prefix

local log = require("log")
local info = log.new()

info:set_prefix("[INFO] ")
info:printf("%s %f", "ok", 1.2)
-- [INFO] ok 1.2

Set flags

local log = require("log")
local info = log.new()

info:set_prefix("[INFO] ")
info:set_flags({date=true, time=true})
info:printf("%s %f", "ok", 1.2)
-- [INFO] 2019/05/23 22:23:03 ok 1.2

info:set_flags({date=true, time=true, longfile=true})
info:printf("%s %f", "ok", 1.2)
-- [INFO] 2019/05/23 22:23:03 ./a/b/c.lua:17: ok 1.2

Output

local log = require("log")

local info, err = log.new("/path/to/file.log")
info:close() -- don't forget
info:set_output("/path/to/file2.log") -- write to new file
info:close()

-- prefix
local info, err = log.new("/path/to/file.log", "[INFO] ")
info:print("ok")
info:close() -- don't forget

-- flags
local logger_flags = {
    date=true,
    time=true,
    microseconds=true,
    utc=true,
    longfile = true,
}
local info, err = log.new("/path/to/file.log", "[INFO] ", logger_flags)
info:print("ok")
info:close() -- don't forget

-- to stdout/stderr
local info, err = log.new("/path/to/file.log")
info:close() -- don't forget
info:set_output("STDOUT") -- to STDOUT
info:set_output("-") -- to STDOUT
info:set_output("STDERR") -- to STDERR

loglevel - usage similar to slf4j

local log = require 'loglevel'
log.set_default_output('some-file-on-disk') -- defaults to "STDOUT"

-- Logs go to /dev/null
log.DEBUG:print('foobar')
log.DEBUG:printf('foo bar %s', 'baz')

-- Logs go to some-file-on-disk (the default_output setting)
log.set_level('DEBUG') -- defaults to "INFO"
log.DEBUG:print('foobar')
log.DEBUG:printf('foo bar %s', 'baz')

-- Other loggers
log.DEBUG:print('debug')
log.INFO:print('info')
log.WARN:print('warn')
log.ERROR:print('error')

-- Log levels
log.set_level('DEBUG')
log.set_level('INFO')
log.set_level('WARN')
log.set_level('ERROR')