RE: overriding method of a single object and calls its metatable method ?
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- Subject: RE: overriding method of a single object and calls its metatable method ?
- From: "Jerome Vuarand" <jerome.vuarand@...>
- Date: Mon, 5 Mar 2007 18:36:49 -0500
gary ng wrote:
> Given the following construct(as mentioned in PIL)
>
> A={}
>
> function A:new(o)
> local o=o or {}
> setmetatable(o,self)
> self.__index = self
> end
>
> function A:foo()
> print("foo of A")
> end
>
> a=A:new()
>
> how can I easily define a method a.foo which is equivalent to this :
>
> function a.foo()
> a.super.foo()
> print("foo of a")
> end
>
> which has this output :
>
> foo of A
> foo of a
Here is a slightly modified version of your code that do what you want.
I put three alternative solutions. foo is the closest from your original
example. bar is slightly better. baz is the best. IMHO baz is the way to
go.
A={}
function A:new(o)
local o=o or {}
setmetatable(o,self)
self.__index = self
self.super = self --< You can simply define super to point to the
class itself
return o --< You forgot to return the object
end
function A:foo()
print("foo of A")
end
function A:bar()
print("bar of A")
end
function A:baz()
print("baz of A")
end
a = A:new()
function a.foo()
a.super.foo()
print("foo of a")
end
function a.bar(a) --< You should pass a as parameter
a.super.bar()
print("bar of a")
end
function a:baz() --< Even better, use implicit self
self.super.baz() --< Here use self instead of a
print("baz of a")
end
a.foo()
a:bar() --< Method syntax is more suited to methods
a:baz() --< Method syntax is more suited to methods