[Python-Dev] PEP 3144 review.

[Peter Moody]

On Tue, Sep 15, 2009 at 4:34 PM, Scott Dial
<scott+python-dev at scottdial.com> wrote:
> R. David Murray wrote:
>> On Tue, 15 Sep 2009 at 21:58, Antoine Pitrou wrote:
>>> Le mardi 15 septembre 2009 à 15:48 -0400, R. David Murray a écrit :
>>>> However, I do not think
>>>> that the proposed API should accept, eg, IPv4Network('192.168.1.1/24')
>>>> as valid.  That's just too confusing and error prone.
>>>
>>> Indeed, it should throw some kind of ValueError instead.
>>
>> Peter, what do you think?

I disagree. It seems overly pedantic to throw a valueerror on this.
IPy does (used to do?) this and it's one of the primary reasons I
wrote ipaddr.

> This change would have to be dependent on Antoine's suggestion of:
>
>    >>> addr, net = parse_address_with_mask('192.168.1.1/24')
>    >>> addr == IPv4Address('192.168.1.1')
>    True
>    >>> net == IPv4Network('192.168.1.0/24')
>    True
>
> Otherwise, I am ok with this change too. It resloves the weird duality
> of IPv4Network. And as RDM says, anyone who wants the
> IPv4AddressWithNetwork functionality can just role it themselves. At the
> moment of iteration, you have access to what network it is and can build
> your own IPv4AddressWithNetwork objects.

now, I understand that as the author, I have certain biases, but I'm
not having the same difficulty with this duality as others.  I really
don't even see it as a duality.

It seems as though your issue could more easily be solved by having an
iterator in BaseNet which returns a new network object with the
original prefix length.

eg:

for addr in ipaddr.IPv4Network('1.1.1.0/24').iterwithnetmask():
  # 1.1.1.0/24, 1.1.1.1/24, 1.1.1.2/24...

(or better yet, .iterwithprefix)

this can be done much more cleanly/easily than adding two new
(redundant in my eyes) classes and much less pedantically than raising
exceptions w/ IPv?Network() constructor received something other than
base network address.

Is this sufficient? If not, perhaps someone could help me better
understand the confusion over IPv?Network objects.

Cheers,
/peter

> net = IPv4Network('10.0.0.0/24')
> netaddrs = []
> for addr in net:
>    netaddrs.append(IPv4AddressWithNetwork(addr, net))
>
> I guess I am ok with this. It seems sub-optimal (why not just return a
> IPv4AddressWithNetwork to begin with?) but I suppose it is no less
> efficient since the same objects would be constructed.
>
> --
> Scott Dial
> scott at scottdial.com
> scodial at cs.indiana.edu
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