Re: Lua 5.2 and continue

[Martin Poelstra <martin@...>]

> <snip>
>
> Inclusion by "popular request" is not the same as inclusion by "me
> too" count threshold.
> 
> I believe that providing good arguments for your position has much
> better potential.

You're right, an example would probably be better, so here goes.

I wrote a packet parser for a home-automation system. The system will
receive quite some (wireless) noise, thus retrying to match a packet
header on the next few bytes must be possible.

In my current implementation, I have 2 nested loops, and have to use the
'break' statement in places where my brain thinks 'continue'. I would
have written the function like the following, which better fits the
flow-of-thoughts in my brain:

-- pseudo-code...
while true do
	-- Read 10 bytes of data.
	-- Last 9 bytes of previous run are re-used first if needed.
	data = socket:read(10, data:sub(2))
	if not data then
		-- Serious error, break the loop
		break
	end

	-- Check packet start code
	if data:byte(1) ~= 0x47 then
		continue
	end

	-- Parse raw bytes into a table with keys
	pkt = convert(data)
	
	-- More packet validation checking
	if not verifyHeader(pkt) then
		continue
	end

	-- We used all data of this packet, don't re-use any of it
	-- in the next run
	data = ""

	-- Do something with the packet
	if pkt.cmd == CMD_EXIT then
		break
	elseif pkt.cmd == CMD_FOO then
		foo()
	end
end

On the other hand, I do appreciate less is more for Lua...

Grtz!
Martin