Re: Question: Lua Constructor Mechanism

[Max Ischenko <max@...>]

nelson@helikon.com wrote:

> I was trying to play with Lua's simple constuctor mechanism, by using 
> the example used in the document. Namely,
> 
> window1 = Window{ x = 200, y = 300, foreground = "blue" } 
> 
> which is the syntactic sugar for 
> 
> window1 = Window( { x = 200, y = 300, foreground = "blue" ) } with 
> initailization.
> 
> However, I received following error message:
> ----------------------------------------------------------------------
> > window1 = Window{ x = 200, y=300, foreground = "blue" }  
> error: attempt to call global `Window' (a nil value)
> stack traceback:
>    1:  main of string "window1 = Window{ x = 200, y=300,foregroun..." 
> at line 1

For this to work you should define function Window which takes a table
as argument:

function Window(t)
 ...
end

> I expected it should create a instance of "Window" Class (I think in  
> C++. :) ) which internally creates table and the elements within. Of 
> course, I can explicitly create table as a window object.
> But, I am trying to use Lua to simulate C++ syntax for prototyping 
> Therefore, I intend to try this interesting feature.

Lua for prototyping? 
IMHO Lua is best for embedding/extending, but not for pure prototyping.
I suggest Ruby/Python instead.

> 
> I wonder if there is anything need to be created / initailized before 
> constructing a object/instance using lua's constructor mechanism??
> 
> Thanks in advance!! :)
> And enjoy using Lua!!
> 
> Nelson 
> 
> 
> 

-- 
Best regards, Maxim F. Ischenko.