A metamethod to be called when a variable goes out of scope?

[Marc Balmer <marc@...>]

When a variable is marked as to-be-closed with the <close> tag and it goes out of scope, the __close metamethod is called.

What impact would calling a metamethod have, that is called when a variable goes out of scope and that has said metamethod defined?  Would the check for the presence of such a metamethod already introduce an inacceptable overhead?

I am thinking of something along e.g.  __scope(), to be called when a variable goes out of scope?

Thoughts?

- mb