Re: do some operation on a set of values
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- Subject: Re: do some operation on a set of values
- From: Duncan Cross <duncan.cross@...>
- Date: 2010年12月26日 02:52:44 +0000
On Sun, Dec 26, 2010 at 12:32 AM, Peyman <peiman_3009@yahoo.com> wrote:
>> Learn about metatables and metamethods.
>
> there is no way instead of metatables ?
No.
> there is a simple sample of metatables ?
-- create a new metatable
meta = {}
-- define a function that returns a table after giving it our metatable
function valueset(t)
return setmetatable(t or {}, meta)
end
-- add metamethods to our metatable that change behavior for + and *
function meta.__add(set1, set2)
local result = {}
for i = 1, math.min(#set1, #set2) do
result[i] = set1[i] + set2[i]
end
return valueset(result)
end
function meta.__mul(set1, set2)
local result = {}
for i = 1, math.min(#set1, #set2) do
result[i] = set1[i] * set2[i]
end
return valueset(result)
end
-- test it
a = valueset{1, 2, 3}
b = valueset{5, 6, 7}
c = a + b --> {6, 8, 10}
c = a * b --> {5, 12, 21}
-Duncan