Re: string.gsub (Lua 5.1.1)

[Nick Gammon <nick@...>]

On 04/11/2006, at 8:39 PM, Shmuel Zeigerman wrote:

> 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

Judging by the Lua source, it is actually reporting the match count.  
In a sense, the count is accurate if you count replacing "a" by "a"  
as a replacement. However that does not fit with the quoted statement  
"then there is no replacement".

Probably the manual should be reworded as:

"gsub also returns, as its second value, the total number of matches  
made."

Alternatively, change the behaviour of Lua to actually not count the  
cases where the replacement isn't made. However in that case, do you  
count this example:

string.gsub ("a", "a", "a")

You could argue that replacing "a" by "a" is not really replacing it.  
Before Lua 5.1, if you wrote a replacement function you had to be  
careful to return the original text if you couldn't make a  
replacement, now returning nil does the same job.

- Nick