function string.test(s)
print('test')
end
a = 'bar'
string.test(a)
a:test()
All is fine until next example.
function table.test(s)
print('test')
end
b = {1,2,3}
table.test(b)
b:test() -- error
Why do I getting the error?
It was working fine at strings.
Tables do not have a metatable by default like strings do.
Try instead:
function table.test(s)
print('test')
end
b = setmetatable({1,2,3}, {__index=table})
table.test(b)
b:test() -- error
While daurn answers your question nicely, allow be to explain why this is.
In Lua, all datatypes can have a metatable. (Although it's quite different when dealing with numbers,bools,etc. See debug.setmetatable.) This includes the string. By default this is set to index string library with __index, it is when make syntactic sugar like print(s:sub(1,5)) (s being a string) possible.
This is NOT the same with tables. By default tables have NO metatable. You have to manually set it with setmetatable.
And to conclude my answer, enjoy this code snippet
debug.setmetatable(0,{__index=math})
debug.setmetatable(function()end,{__index=coroutine})
debug.setmetatable(coroutine.create(function()end), {__index=coroutine})
local function Tab(tab)
return setmetatable(tab,{__index=table})
end
This basically allows you to use math functions on numbers
local x = 5.7
print(x:floor())
And do similar things with functions and threads, using coroutine functions:
print:create():resume()
Pretty hacky if you ask me
And of course, create tables and use table functions on them:
local x = Tab{1,2,3,4}
x:insert(5)
x:remove(1)
print(x:concat(", "))
I find it hard to imagine anybody who don't like cool tricks like that.
