[Python-Dev] PEP 3144 review, and the inclusion process (original) (raw)

Andrew McNamara andrewm at object-craft.com.au
Tue Sep 29 03:40:18 CEST 2009

I've never said otherwise. In fact, from an email last night, "If what the community requires is the library you've described, then ipaddr is not that library." The changes you require make ipaddr significantly less useful to me. I'm not prepared to make those changes in an attempt seek acceptance to the stdlib, especially if the stdlib is in such flux that I'll get to do this again in 18 months.

The point is that, having brought it to us, we all now have an interest in the outcome. Whatever goes into the standard library is going to be something that we have to live with for a long time, and now is our best chance to shape the result.

I understand your concern over introducing more classes, however I still feel my suggested functional decomposition is worth that cost because I consider the behaviour of my suggested classes to be more intuitive. I should mention that I am not a computer scientist, and none of this is motivated by a desire for theoretical purity - just practical experience.

One of my concerns now is that if a code block receives an IPv4Network instance, it does not know whether this represents a host address with mask, or a network address. In some contexts, this distinction is critical, and confounding them can result in delayed error reporting or erroneous behaviour. Your addition of a strict flag does not completely address this concern as it assumes the instantiation and use occur in proximity, which is often not the case in large projects.

I suspect you are also mistaken in thinking my proposed changes make the module less useful for you - maybe you can describe the problem as you see it?

As a reminder to people who have come late to this thread, I proposed three classes per protocol:

IPv?Address
    A single address

IPv?AddressWithMask
    A single address with implied IPv?Network

IPv?Network
    A container-like network address (with strict mask parsing)

Further:

In cases where you want to allow lax specification of network addresses, this would be spelt:

IPv?AddressWithMask(some_address).network

At first glance, this seems somewhat round-about, however it makes explicit the potential loss of bits.

-- Andrew McNamara, Senior Developer, Object Craft http://www.object-craft.com.au/

More information about the Python-Dev mailing list