[Python-Dev] PEP 3144 review. (original) (raw)

Greg Ewing greg.ewing at canterbury.ac.nz
Thu Sep 17 01:56:25 CEST 2009

R. David Murray wrote:

A network is conventionally represented by an IP address in which the bits corresponding to the one bits in the netmask are set to zero, plus the netmask.

Okay, that's clarified things for me, thanks.

In that case, we shouldn't be talking about a "network address" at all, but just a "network", and it makes sense to have

  1. A class called IPNetwork that contains an IP number and a mask, with the IP number constrained not to have any ones where the mask has zeroes, and

  2. A class called IPAddress which only contains an IP number.

It seems that some people would also like to have

  1. A class called IPAddressWithMask that contains an IP number and a mask, with no constraints,

but I'm not enough of an expert to know whether such a thing would be used often enough to be worth having a special type for it, as opposed to using an (IPNetwork, IPAddress) pair, or attaching a 'network' attribute to an IPAddress, or some other solution when the need arises.

-- Greg

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