Client Quit should notify channel members.

[ahf]

Once a client sends a QUIT-message, it's important that said message should be send to each client, that shares at least one channel with the quitting client, exactly once.

The algorithm for doing this, is going to be something in the line of:

q := QuittingClient
n := ClientSet // Set of client's that has already been notified.

for each channel that q is in:
for each client in channel:
if not n.Contains(client):
client.Quit(q) // Let client know that q QUIT.
n.Insert(client)

[jlouis]

I'd build a notifier-set of clients that should be notified by querying each channel the client is on currently. Of course adding an already present notifier to this set is a no-op. After I have this set, i'll simply post the quit to each one in it.

It is the transpose of your implementation. It may be easier:

 q := QuittingClient
 n := ClientSet

 for each ch q is in:
   n.AddMembers(channel.Members())

 for e in n:
   e.Quit(q)