How do I lock a table? (How more specific can this get!?)

I don't have any piece of code to provide, since this is more of a general question rather.

But, like Roblox's base "string" and "math", how would I lock the table?

I would go for metatables via a __call function, __index and __newindex modification. But, I'd like to do it how Roblox does it.

Since you can't call "pairs()" on metatables, in the sense you can't get the metatable content without doing getmetatable(). I'd assume you could make some modification to pairs() to allow getmetatable() with just name.