Re: string.gsub accepting a callable userdata

[Roberto Ierusalimschy <roberto@...>]

> string.gsub is one of the most powerful Lua functions we have, and the
> substitution may be a string, a table, or a function.
> 
> It would be useful if this list could be extended to include callable
> userdata - in most language interop situations I've encountered,
> foreign functions are represented in this way on the Lua side.
> 
> (It would be too confusing to allow callable _tables_ of course)

What about indexable userdata? Given a userdata, should we use __index
or __call?

-- Roberto