At sign ``@'' in key

[Grizzly Bear <6grizzlybear@...>]

Hi,

I'd really want to have the at sign ``@'' in the key of a table, e.g.,

          tab["var@addr"] = 1.

But I haven't been able to do 

          tab.var@addr = 1.

The error message was 

          stdin:1: '=' expected near '@'

I'm using Lua 5.1.5. Any suggestions?

Thanks.

Wei