On Wed, Aug 19, 2009 at 9:21 AM, R. David Murray<rdmurray@bitdance.com> wrote:
On Wed, 19 Aug 2009 at 08:19, Peter Moody wrote:
On Wed, Aug 19, 2009 at 6:47 AM, Tino Wildenhain<tino@wildenhain.de> wrote:
Le Tue, 18 Aug 2009 13:00:06 -0700, Peter Moody a écrit :
o.broadcast
IPv4Address('1.1.1.255')
this is often used but not the only valid broadcast address, in fact, any address between network address and max(address with given netmask) can be defined as broadcast. Maybe biggest or greatest would be better name for the attribute. User is then free to interpret it as broadcast if desired.
The attribute network returned as address object also does not seem right.
by convention, the highest address in a given network is called the broadcast address while the lowest address is called the network address. They're also distinct addresses, as opposed to networks, hence .broadcast/.network/etc returning IPvXAddress objects. calling them .biggest and .smallest would be confusing.
am I misinterpreting what you mean?
Possibly. Tino means exactly what he said: the broadcast address does not _have_ to be the last IP, nor does the last IP _have_ to be a broadcast, though in practice they almost always are (and using the last IP as a host IP almost never works in practice in a heterogeneous network). Check out the 'broadcast' option of the ifconfig command for confirmation that the broadcast address can be any IP in the network. Of course, for that to work all hosts on the network have to agree on what the broadcast is, hence the normal convention that the broadcast is the last IP in the network.
As for the 'network' attribute, if you call it 'network' IMO it should be a network data type, which would make it rather redundant. What you are actually returning is what I have normally heard called either the 'zero' of the network, or the "network number" or "network identifier"; but never just "network" (a network has to have at least an implicit netmask to be meaningful, IMO).
Since you are dealing with networks as a list of addresses, perhaps you should drop the 'network' attribute, make the 'broadcast' attribute settable with a default equal to self[-1], and let the user refer to the zero element to get the zero of the network if they want it.
making the broadcast address settable (with a default to self[-1]) might be reasonable, though it is different from just about every other python implementation I've seen (IPy, ipv4.py, netaddr). I'm not sure I understand your point about the network attribute. what I'm returning with network is the subnet-id/base address of the given network. Again, .network seems to be fairly standard for naming.
--David