Re: [Boost-users] Need boost's help with poor design

From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2008-03-26 22:20:52

AMDG

Robert Dailey wrote:
> After investigating this a little more (plus from the answers you 
> provided above) I think I fully understand the problem. My only 
> concern at this point is compile time, as you pointed out. For 100 
> packet types, do you think compile time would be noticeably affected 
> (assuming that all of the boost includes are in a precompiled header 
> file)? How about for 1000 packet types?

1000 packet types is unfeasible because mpl uses the preprocessor
lib to generate the vector specializations--Boost.Preprecessor has
a hard limit of 256 and some preprocessors give out even before that
point.

It turns out that MPL does not actually permit the upper limit
of 50 to be configured.  This a little annoying especially because
all the framework needed is already in place.  I had to use a private
header to generate vector100 for a test (It took 43 seconds to
compile, BTW)

If you have so many types of packets, you are probably better off
using runtime dispatching.

typedef boost::unordered_map<PacketID, boost::function<void(Packet 
const&)> > dispatcher;

and then store references to the individual signals along with the 
downcasting logic
in the boost::function<>s

In Christ,
Steven Watanabe