OOP in gideros

mumuja

According to the guide:

gideros.class function is used to create your own classes through inheritance. You can only inherit from Gideros API's own classes (EventDispathcher, Sprite, etc.) and you cannot inherit from your own classes.

However, I have successfully extend from my own class?
Here is the snippet of code, granted that the base class is still the API class

Parts = gideros.class(Sprite) Parts.position = {x = 0, y = 0} function Parts:init() end -------------------------------------------- Head = gideros.class(Parts)--Parts is something I define myself   function Head:init() end -------------------------------------------- local test = Head.new() print(test.position.x) --prints 0

Either the guide is misleading or this is an unintended feature.

atilim

In fact, it's an unintended feature

At first I think that init functions may not be called correctly, but they're called and with the correct order (first Parts:init, then Head:init)

After doing more tests, I will update the documentation

Thank you,

Rickyngk

Hi,

@atilim: I need this too. So, can I use that way officially ? Did you update documents?
Thank Mumujar!

Thank you,

atilim

Yes we've extended the class system and tested by inheriting multiple times. You can use it officially with the new release.

MikeHart

Nice to know. Thanks!

Rickyngk

If I split the code into 3 files as following:
--------------------------------------------
--File1.lua
--------------------------------------------

Parts = gideros.class(Sprite) Parts.position = {x = 0, y = 0} function Parts:init() end

--------------------------------------------
--File2.lua
--------------------------------------------

Head = gideros.class(Parts)--Parts is something I define myself   function Head:init() end

--------------------------------------------
--File3.lua
--------------------------------------------

local test = Head.new() print(test.position.x) --prints 0

Then, I've got issue:

[string "property.lua"]:138: attempt to index upvalue 'b' (a nil value) stack traceback: [string "property.lua"]:138: in function 'new'

Edit: It's ok if merge file1 and file2

MikeHart

Must be something else. If I take this pure code, I get no errors in 2012.2.

hnim

run with no error in beta8

Rickyngk

Sorry, my mistake,
File 1:

Head = gideros.class(Parts)--Parts is something I define myself   function Head:init() end

File2:

Parts = gideros.class(Sprite) Parts.position = {x = 0, y = 0} function Parts:init() end

MikeHart

What is the difference to your second last posting? Still get no error.

hnim

i got another error event i merge file 1 and file 2 (test.position is always nil)

f3.lua:2: attempt to index field 'position' (a nil value) stack traceback: f3.lua:2: in main chunk

If i place Part definition before Head, everything is ok. I think problem is order when compile code

MikeHart

Of course it would be. if you execute fiel1 before file2, then Parts is undefined. Make sure you set the order correctly in your project settings.

moopf

Hmm, trying out inheritance at the moment. I have this:

RoomWrapper = gideros.class(Sprite)   function RoomWrapper:init() self.props = {}   end   function RoomWrapper:thisIsMyTest() print ("in room wrapper!") end

Room = gideros.class(RoomWrapper)   function Room:init() self:thisIsMyTest(); end

However, I get "attempt to call method thisIsMyTest (a nil value)".

It's been a long day so I'm probably missing something obvious here.

MikeHart

Works fine with me. Make sure you have your files in the correct order.

moopf

Hmm, do you mean in the Project bar on the left? Or is there somewhere else to set the execution order of .lua files?

moopf

Ah, not to worry, just found the 'Code Dependencies' option in the menu when you right click on a Lua file. Hadn't seen that before.

MikeHart

Glad you figured it out.

Caroline

@atilim - I tried to sign up with the bug tracker so that I could write this there, but I never got a confirmation email, so couldn't sign in.

After doing more tests, I will update the documentation

I think this still needs updating on this page:
http://www.giderosmobile.com/documentation/classes_in_gideros.html, as you can inherit from your own classes(?):

Core.class function is used to create your own classes through inheritance. You can only inherit from Gideros API’s own classes (EventDispathcher, Sprite, etc.) and you cannot inherit from your own classes.

For example, you can create your EventDispathcher class like:

MyEventDispathcher = Core.class(EventDispathcher)

Also Dispatcher's spelled wrong.

gorkem

Caroline - just confirmed your email. There's an issue with how bugs.giderosmobile.com sends emails.

atilim

Hi Caroline,

I've changed all "*Dispathcher"s to "*Dispatcher" and updated the documentation.

Thank you

ndoss

There's duplicate Gideros documentation in under the Gideros Academy links and in the Ultimate Guide to Gideros and both and aren't always updated. For example:

* The document about classes under Gideros Academy isn't correct regarding inheritance from user classes.

* The document in the Ultimate Guide to Gideros still has the dispatcher spelled incorrectly (well, it did ... I corrected it).

A suggestion: change pointers in Gideros Academy so that they point into the Ultimate Guide to Gideros (where appropriate) so you don't have to maintain two copies of the same information.

OZApps

@Atilim, am I wrong if I presume that now I can inherit from any class, do not have to inherit from the Sprite class (if the class is non visual)? I guess that would also have some optimisation in terms of memory usage as it would not have all the visual stuff that might not be required. is my understanding right?

atilim

@OZApps exactly

A = Core.class() --> create a base class B = Core.class(A) --> inherit B from A C = Core.class(B) --> inherit C from B

Cyberience

Then could I assume you can not override the init? by making a new init for a second of 3rd level object?
Regards

In fact, it's an unintended feature

At first I think that init functions may not be called correctly, but they're called and with the correct order (first Parts:init, then Head:init)

After doing more tests, I will update the documentation

Thank you,

ar2rsawseen

@Cyberience no you can't, for that purpose you can use postInit method.
postInit is called after init method upon creation.
So you can define in parent class to do something in postInit and then redefine the postInit method in child class.

Here is a reference to the thread about postInit http://www.giderosmobile.com/forum/discussion/2506/is-it-possible-to-call-subclasss-overwrited-function-in-baseclasss-init-function/p1