property callback ?

yuewah · May 2012

any better approach for the following feature ?

http://blog.anscamobile.com/2012/05/tutorial-property-callbacks/

OZApps · May 2012

Could you reiterate what you are looking for, do you want to replicate this in Gideros or do you want to make this better?

For replication, 99% of the code is Lua code so will work as is.

As for bettering it, in what way would you want to make this better?

atilim · May 2012

And as a personal taste, I don't prefer attaching callback functions to table fields by using __index and __newindex. Mainly because it's really easy to forget (and hard to maintain) the connections between fields and callback functions when there are many.

I find this kind of approach easier to understand and maintain:

function Game:updateHealth(health)
    self.health = health
    -- update UI
    -- check < 0, if so dispatchEvent(Event.new("gameOver"))
    -- do other things
end

OZApps · May 2012

@Atilim, that article is for a framework that does not work with OO. In fact the proxy object is a little flawed, I had a little more elaborate proxy object (and of course no listeners) for the compatibility layer between Gideros and that framework.

It is painful to support every property that can be set using the assignment, in Gideros, it may take a little bit of orientation, but then nearly all the API functions are function and not assignment operators.

In the sense

myImage.x  = 10

and

myImage:setX(10)

and then .isVisible vs :getVisible, .alpha vs getAlpha() that was made to abstract away the setters and getters. Good in the short term, but problematic in the long run for *serious* developers.

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