Re: [ANN] Lua 5.4.0 (alpha) now available

[Andrew Gierth <andrew@...>]

>>>>> "Patrick" == Patrick Donnelly <batrick@batbytes.com> writes:

 >> In 5.4, io.lines explicitly _does_ integrate with the generic for
 >> loop to ensure the file is closed (if it was opened and isn't just
 >> using io.input). What makes you think there is not?

 Patrick> Sorry, I meant that there is no integration with generic for
 Patrick> loop and the toclose variables, i.e. that breaking out of the
 Patrick> for loop will cause the state value to be closed.

But this integration does exist. Why do you think it does not?

The generic for loop in 5.4 takes 4 values, not 3, and the 4th one is
treated as being assigned to a toclose variable. That is to say,

  for foo in a,b,c,d do ... done

will invoke d's __close metamethod when the loop is exited by any means.

io.lines("file") now returns 4 values: readline_func, nil, nil, file
where the readline_func is a closure that returns the next line from the
file, and "file" is the filehandle that was opened, which will be closed
via its __close metamethod.

-- 
Andrew.