Re: Lua OOP modules with property support

[luciano de souza <luchyanus@...>]

At my current stage, your code, Andrew,  sounds very enigmatic for me.
I don't know how to use metatables. From what I was able to glean,
it's a very hard subject. But it's also true the bennefits are very
good. There are lots of things to learn. If I put myself the condition
to understand metatable to advance in Lua, the results will delay and
this is very negative for motivation. However, I think you are right.
I understood how to use Classlib, I like Classlib, handling
metatables, I will able to create properties.

Cosmin, I took a look in three files you sent me. As there is a large
quantity of code, I don't know if I will able to decode it. As I know
only a few of Lua, I have short skill in review codes and make
conclusions. For this reason, I have prefered to use only well
documented libraries. Classlib is one of them. the problem is that
there's no native support for properties.

Well, it's time to study, study and verify if this is the moment to
use properties!


2012/6/28, luciano de souza <luchyanus@gmail.com>:
> Hello all,
>
> I wasn't acquainted with OOP strategies in Lua. What I know is that we
> have nice options like Classlib, Loop, LOS... and the raw handling of
> metatables.
>
> Supppose the following structure:
>
> -- [[
> class number
> method GetValue
> property value
> ]] --
>
> Now suppose the following function:
>
> function number:GetValue()
> return math.random(100)
> end
>
> I would like to do something like that:
>
> number = number()
> print(number.value)
>
> The reply could be 80, 35, 44 or any randomic value between 0 and 100.
>
> Using Classlib, LOOP or any other Lua library with OOP support, how
> can I do this?
>
> Could I directly handle the metatables? Certainly, I could do it, but
> regarding my very few experience with metatables, I would prefer to
> use a module with native property support. But is there this module?
>
> Luciano
>
>
> ---------- Forwarded message ----------
> From: luciano de souza <luchyanus@gmail.com>
> Date: Wed, 27 Jun 2012 03:03:44 -0300
> Subject: Defining a property with classlib
> To: Lua mailing list <lua-l@lists.lua.org>
>
> Hello all,
>
> I am trying to implement a property with classlib, but the code does not
> work:
>
> require('classlib')
>
> class.number()
>
> function number:__init()
> local mt = getmetatable(self)
>
> function mt.__index(t, k)
> if k == 'value' then
> return math.random(1000)
> end
> end
> end
>
> number = number()
> print(number.value)
>
> In stead of showing a ramdomic number, classlib raises an error.
>
> This code works:
>
> setmetatable(_G, {__index = function (t, k) return math.random(1000) end})
>
> I would like to to the same but in the class scope. For this reason, I
> tried also:
>
> require('classlib')
>
> class.number()
>
> function number:__init()
> local mt = getmetatable(self)
>
> function mt.__index(t, k)
> if k == 'value' then
> return math.random(1000)
> end
> end
> setmetatable(self, mt)
> end
>
> number = number()
> print(number.value)
>
> How to define a property using classlib?
>
> Luciano
>