Re: :? syntactical sugar request

[Steve Dekorte <steve@...>]

Luiz Henrique de Figueiredo wrote:
> > That works if you always want that behavior, but I'd like it to only
> > return the nop function in particular cases.
>
> If those "particular cases" depend on the table or index, then you can 
> write
>
>  settagmethod(tag(object),"index", function (t,i) DO SOMETHING HERE end)

I should have been more specific - I'd like to be able to use both types 
of lookups on the same table.

For example:

function ChatApp:draw()
  self:drawOutputText()
  ...
end

function Socket:receive()
  ...
  self._delegate:?socket_received_(self, data)
end


In this example, the Socket's delegate happens to be the ChatApp. I'd 
like the delegate message to be sent if the ChatApp implements the 
socket_received_ method and to be ignored otherwise, but I want the 
drawOutputText to raise an error if it's missing. Same table, different 
lookup behavior.

Steve