Quick questions about Gideros&Lua

rrraptor · November 2019

How to properly use second parameter to Core.class()?
I have a hierarchy like: Sprite <- foo <- bar <- abc
I did this:<pre class="CodeBlock">

 foo = Core.class(Sprite)
 
function foo:init(param)
	assert(param ~= nil, "Overide me")
	self.param = param
	print("Output from foo", self.param)
end
 
bar = Core.class(foo)
 
function bar:init(param)
	print("Output from bar", self.param)
end
 
function bar:ok() print("bar ok") end
 
abc = Core.class(bar, function(a) return a end)
 
function bar:init(param)
	print("Output from abc", self.param)
end
 
local a = abc.new("yo")
a:ok()

Ouput:

Output from foo yo
Output from abc yo
bar ok

Why there is no "Output from bar"?

hgy29 · November 2019

I see two definitions for bar:init() but none for abc:init() ...

rrraptor · November 2019

Omg, Im so stupid...
Anyways, any info about 2d args Core.class([base, args]) parameter?

hgy29 · November 2019

the second arg should be a function that will returns the args to pass to the base class when constructing it

rrraptor · November 2019

How TextField's "h" parameter in layout properties works?
I tried different values (big, small, negative), but seems like its competently ignored. Correct me if Im wrong.

hgy29 · November 2019

It is only used if you want to center vertically or bottom align your text

rrraptor · November 2019

~~So it shoud not work with TLF_CENTER? And if so, I need to center it by myself?~~

Code:

Label = Core.class(TextField, function(t) return nil,t.text,"" end)
 
function Label:init(params)
	self:setLayout{
		flags = FontBase.TLF_CENTER|FontBase.TLF_REF_TOP,
		w = params.w, h = params.h or 0
	}
	self.ax = params.ax or 0
	self.ay = params.ay or 0
	self.offsetX = params.offsetX or 0
	self.offsetY = params.offsetY or 0
	self:setPosition(self.offsetX, self.offsetY)
end
 
local w, h = 70, 200
local scale = 2
 
local l = Label.new({text="Sample multiline text", w = w, h = h})
l:setTextColor(0xffffff)
l:setScale(scale)
l:setPosition(100, 100)
stage:addChild(l)
 
local px = Pixel.new(0xff0000, 0.3, w*scale, h*scale)
px:setPosition(l:getPosition())
stage:addChild(px)

Edit: turns out that TLF_CENTER is horizontal center, and I shoud use TLF_VCENTER also, silly me

flags = FontBase.TLF_REF_TOP|FontBase.TLF_VCENTER|FontBase.TLF_CENTER

rrraptor · November 2019

Is it posible to inherit meta methods like __tostring() ?

Lets say I have

GlobalID = 0
 
foo = Core.class()
function foo:init()
	GlobalID += 1
	self.id = GlobalID
end
function foo:__tostring()
	return string.format("Object [%i]", self.id)
end
 
bar = Core.class(foo)
function bar:init() end
 
local a = foo.new()
print(a) -- > give us "Object [1]"
local b = bar.new()
print(b) -- > give us "table: xxxxxxxx"

But I want to print ID for bar object too.

I have one solution, but I dont like it, maybe ther is more elegant way of doing this?

GlobalID = 0
 
foo = Core.class()
function foo:init()
	GlobalID += 1
	self.id = GlobalID
	self:gen()
end
function foo:gen()
	local t = getmetatable(self)
	t.__tostring = function(v) return string.format("Object [%i]", v.id) end
	setmetatable(self, t)
end
 
bar = Core.class(foo)
function bar:init()
	self:gen()
end
 
local a = foo.new()
print(a) -- > "Object [1]"
local b = bar.new()
print(b) -- > "Object [2]"

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