Re: Question about __index and classes

[Should Pain <pengzhicheng1986@...>]

于 2011-8-28 6:52, Michael Kirsch 写道:
> There is something I don't understand about the way __index and
> metamethods work. The way I understand, the "." operator looks in the
> table itself and the ":" operator looks directly in the metatable. If
> so, then why is it necessary to say:
>
>      MyClass.__index = MyClass
>
> for you to be able to use ":"?
>
> If ":" looks right in the metatable, then it shouldn't be needed. To
> me it seems like what it would do is let you call metamethods using
> the "." operator, but it doesn't work that way for some reason.

many people have given the right answer,

I would just say one more setence.
although the `colon call' is said to be a syntactic sugar, it is in fact treated not exactly the same way
as the 'dot index' in that the `colon call' evaluate the `prefixexp' only ONCE,
and the lvm has an dedicated opcode (OP_SELF) specially for the `colon call'.