Logging in Lua/Gideros

trostik · June 2012

Hi guys,

Wanted to share a code snippet for logging your project. ( currently used/tested for items that have stage "ref" )

In main.lua add:
stage:addEventListener("logEvent",
function(event)
print(os.date(),"LOG:" , event["log"])
end
)

in any Sprite add:
function sendLog(message)
event = Event.new("logEvent")
event["log"] = message
stage:dispatchEvent(event)
end

and then use like this:
function someFunction()
sendLog("someFunction called")
end

The log will look something like :
Sat Jun 9 21:41:37 2012 LOG: soundButtonHandler
Sat Jun 9 21:41:37 2012 LOG: soundButtonHandler
Sat Jun 9 21:41:38 2012 LOG: howToHandler
Sat Jun 9 21:41:38 2012 LOG: howToClick
Sat Jun 9 21:41:38 2012 LOG: goToStage
Sat Jun 9 21:41:38 2012 LOG: goBackToStage
Sat Jun 9 21:41:39 2012 LOG: startButtonHandler
Sat Jun 9 21:41:39 2012 LOG: startButtonClick

Hope it helps.

trostik · June 2012

Remake here :

Create an object called logger:
logger = Core.class()

function logger:init(t)
print("logger here")
end

function logger:log(message)
print(os.date(),"LOG:" , message)
end

init in main
logger = logger.new()

and then call from everywhere:
logger:log("goBackToStage")

atilim · June 2012

Thank you @trostik. Also one of the advantage of your logger class is that you can disable the logging before releasing your app.

For who doesn't use a logger class, redefining an empty print function as:

function print()
end

can also improve the performance of your app before releasing.

victor_wujitouch · July 2012

I use a slightly different approach so I can disabled logging per file and so I can keep most of the syntax used for calling print(args)

-- <a href="http://www.lua.org/pil/5.2.html" rel="nofollow">http://www.lua.org/pil/5.2.html</a>
function Log:log(enabled, ...)
	if enabled == true then
		print(unpack(arg))
	end
end

Then I define a local variable in each class to enable logging in my calls to log()

-- variable definition
local logEnabled = true

-- example call
Log:log(logEnabled, 'Test', 'Message')

ktc · October 2012

@ victor_wujitouch the unpack is the trick I have been looking for. Other implementations cannot print multiple arguments, unpack(arg) can.. Good job.

paulclinger · October 2012

@ktc, using "arg" has been deprecated: http://www.luafaq.org/#T8.1.1

In the example above you should be able to simply write "if enabled then print(...) end"

ktc · October 2012

@paulclinger thanks. Good to know.

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