The Manual states:
> string.gsub (s, pattern, repl [, n])
>
> Returns a copy of s in which all occurrences of the
> pattern have been replaced by a replacement string
> specified by repl, which may be a string, a table, or a
> function. gsub also returns, as its second value, the
> total number of substitutions made.
<snip>
> If the value returned by the table query or by the
> function call is a string or a number, then it is used as
> the replacement string; otherwise, if it is false or nil,
> then there is no replacement (that is, the original match
> is kept in the string).
So each of the following calls
string.gsub("a", "a", function() end)
string.gsub("a", "a", {})
should return "a", 0
However each of them returns "a", 1
--
Shmuel
