RE: Little help with Getters, Setters and Native integration
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- Subject: RE: Little help with Getters, Setters and Native integration
- From: jdarling@...
- Date: 2006年3月31日 08:13:11 -0700
I'm using the code from: http://lua-users.org/wiki/InheritanceTutorial
If I understand properly then I'll want to modify the code quite a bit
to allow for my stuff to work. For example right now they use:
local new_class = {}
local class_mt = { __index = new_class }
newinst = {}
setmetatable( newinst, class_mt )
If I understand properly I'll want to modify thusly:
local new_class = { __index = MyFindGetter, __newindex = MyFindSetter
}
local class_mt = { __index = new_class }
newinst = {}
setmetatable( newinst, class_mt )
function MyFindGetter(self, PropertyName)
if PropertyName=='Width' then
return GetWidth(self.ID)
end
return new_class.__index(self)
end
function MyFindSetter(self, ProeprtyName, Value)
if PropertyName=='Width' then
SetWidth(self.ID, Value)
else
new_class[PropertyName] = Value
end
end
Or am I completely off on this?
- Jeremy
"Help I suffer from the oxymoron Corporate Security."
> -------- Original Message --------
> Subject: Re: Little help with Getters, Setters and Native integration
> From: David Given <dg@cowlark.com>
> Date: Fri, March 31, 2006 8:33 am
> To: Lua list <lua@bazar2.conectiva.com.br>
>
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> jdarling@eonclash.com wrote:
> [...]
> > If I have: GetWidth and SetWidth is their a way to have a table entry of
> > Width that calls GetWidth and SetWidth automatically? I know I have to
> > play with __index, but I can't seem to wrap my brain around it.
>
> __index is called when reading from a non-existent table entry,
> __newindex when writing to one. So you can use a metatable of:
>
> {
> __index = function(t, k)
> if (k == "width") then
> return GetWidth()
> end
> end,
>
> __newindex = function(t, k, v)
> if (k == "width") then
> SetWidth(v)
> end
> end
> }
>
> You have to make sure never to set t.width, though, or these will never
> get called.
>
> - --
> +- David Given --McQ-+
> | dg@cowlark.com | "Those that repeat truisms, are also forced to
> | (dg@tao-group.com) | repeat them." --- Anonymous from Slashdot
> +- www.cowlark.com --+
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