RE: Making a string indexing metamethod
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- Subject: RE: Making a string indexing metamethod
- From: "Jerome Vuarand" <jerome.vuarand@...>
- Date: Wed, 8 Nov 2006 10:38:03 -0500
Reuben Thomas wrote:
> To allow string methods to continue to work, you can't just override
> __index. After some thought, I came up with this:
>
> -- @func __index: Give strings a subscription operator
> -- @param s: string
> -- @param n: index
> -- @returns
> -- @param s_: string.sub (s, n, n)
> local oldmeta = getmetatable("").__index
> getmetatable("").__index =
> function (s, n)
> if type (n) == "number" then
> return sub (s, n, n)
> else
> return oldmeta[n]
> end
> end
>
> What are the downsides?
If oldmeta is a function you have to call it with normal function call
syntax rather than table indexing.
local oldmeta = getmetatable("").__index
getmetatable("").__index =
function (s, n)
if type (n) == "number" then
return sub (s, n, n)
elseif type(oldmeta)=="function" then
return oldmeta(s, n)
else
return oldmeta[n]
end
end