OOP Help :: Getting started with iPhone dev :: Corona / LUA

Perhaps I need to be more specific. I am choosing to learn LUA first, does anyone have any good tutorials they would like to share for this language?

I normally recommend "Programming in Lua" to learn the language if that helps.

I have been reviewing this link along with some tutorials from tutplus. I actually didn't give the programming guide on Lua's site enough of a chance before moving on, but it is actually very good.

The tutorials at tutplus below are a good flash introduction for new Lua users who are looking to use the Corona SDK for mobile development. I think getting well acquainted with the language itself is important before trying to build anything with any SDK, so I will continue my reading on lua.org.

http://mobile.tutsplus.com/series/build-an-endless-runner-game-from-scratch/

This is a topic I've been currently spending a significant amount of time on and just today found an approach that works well for me. My code up to recently has just been procedural, to get things rolling quickly, but now that my code base has started to expand enough it was time to really organize / refactor and part of that in my case meant switching to proper OOP.

First, for general Lua OOP I evaluated many different options, from the most popular (do it yourself metatable variants) to many object libraries, both obscure, amateur, and somewhat widely used.

My short list came to these two. First is MoonScript, which precompiles ".moon" files into Lua. It is a pretty radical transformation of Lua into something more like a cross between Lua and Ruby/Python. I like the syntax and the OOP aspects; in general MoonScript code is 30% smaller than Lua (which itself is already relatively small compared to languages like C++ and Java). By small, I mean low line count and low word count for the same executable functionality. MoonScript adds many of what I'd consider missing and useful features to Lua such as x += 3 and dozens of others.

If I was using Love2D, I probably would go with MoonScript (and that's what its author mostly uses it for successfully). However, for Corona, I felt debugging was somewhat more challenging. I also didn't want to really learn a language "on top of" Lua so to speak, as when I read other Lua libraries that I'm incorporating, it's like going to a different syntax. That said it is something I am highly tempted by so was a really close second choice.

At least for now, I ended up going with "middleclass" for OOP. https://github.com/k.../README.textile

As to part of your other question, OOP design itself I'd consider somewhat language independent, and I'm not sure where to start there. The most important aspect (imo) is to make aggressive use of subclasses (aka inheritance). In other words, from a game perspective, things like: BattleDroid is a child of Robot. LongSword is a child of Weapon. KeyboardInputDatagram is a child of GameInputDatagram. GameInputDatagram is a child of EncryptedDatagram. This is definitely a paradigm shift but once you start to think in terms of objects being children of each other (instead of objects "containing" each other) it really starts to open doors to much more reusable code. It cleans up your code since you no longer see tons of complex nested if statements and that sort of thing.

A couple notes about OOP and Corona in particular. I lost a lot of time figuring out how to integrate OOP and these two methods, and here are the solutions I was able to get working.

The first is timer.performWithDelay. For this, I'll simply refer you to an article that explains the problem and solution, and an actual example from my code:

http://www.coronalab...s-and-counting/

[source lang="plain"]timer.performWithDelay( 250, function () self.thrust_timer(self) end, 0)

function Thrust:thrust_timer ( )
if self.leftThrustIsPressed == 1 or self.leftThrustQueued == 1 then
-- ...
end[/source]




The second issue that took a lot of time for me to find a solution for ended up having a much simpler solution. That is the imageObject.addEventListener method. Without OOP, it is easy enough to use. But how do you pass in a function as an argument, that in turn can access your object instance? Here's how:

[source lang="plain"]function Thrust:initGameObjects ()
-- ...

self.left_thrust_button.owner = self
self.left_thrust_button:addEventListener("touch", self.left_thrust_button_touch)
end

function Thrust.left_thrust_button_touch ( event )
local self = event.target.owner
self.leftThrustQueued = 1
end[/source]


HTH

Corona Labs has started a new tutorial page to help people get started wtih Lua and Corona SDK.

http://www.coronalabs.com/resources/tutorials/

Alternatively to Corona SDK, you can try Gideros Mobile which is totally free (just a splash if you dont purchase) has an adapted OO style for Lua and very good and helpful cummunity. You can check it at http://www.giderosmobile.com