Re: Buffering object

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Wed, 2 Feb 2011 02:06:24 -0800 (PST)
Message-ID:
<6295b5b6-e306-4907-a248-d173026497a0@y12g2000prf.googlegroups.com>
On Jan 27, 10:04 pm, Andrea Crotti <andrea.crott...@gmail.com> wrote:

I have to design something to approach one of the (I think) classical
problems in network.

I need to send out packets (which are objects), but I need to take care
of possible retransmissions.

Suppose I can retransmit 3 times before giving up, I need to
- store the packet somewhere until I'm sure it reached destination
- setup a timer from the first time I send it
- at every timer increase a counter

But the problem is that the timer could be different for all the
packets, so I need "n" different timers (it's an event driven simulation
model) for n different packets.


Not really. Or it depends on what you mean by "timer".

So well I thought to manage all this externally, in a PacketHandler
class.

This class should in my idea take care of:
- create the object dynamically (using new)
- setup the timers and raise the right events
- clear the memory as soon as possible (that's the most important thing)


I wonder if you aren't mixing issues. I suspect that the
packets should be created elsewhere; the PacketHandler should be
private to the logic which is responsible for sending them.

    [...]

And also to make sure that the return type is correct


Huh? Classes don't have return types.

I thought to use a
template class, and then I need to have a PacketHandler for every Data
type, which is again a bit annoying.


Packets are likely represented by a class hierarchy. All your
"consumer" needs to do is to deal with the public interface,
however. (Alternatively: a Packet is nothing more than an
std::vector<char>, or something along those lines.)

So the questions would be:
1. is that bad to allocate with new something outside PacketHandler and pass
   the pointer inside to be eventually freed?


No. It's a very frequent pattern, and it's directly supported
in the standard with std::auto_ptr.

--
James Kanze

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