[Python-Dev] PEP 3144 review.

[Daniel Stutzbach]

On Tue, Sep 15, 2009 at 12:16 PM, Scott Dial
<scott+python-dev at scottdial.com<scott%2Bpython-dev at scottdial.com>
> wrote:

> >>> addr = ipaddr.IPAddress("10.1.2.3/255.255.240.0")
> ...
> ipaddr.IPAddressIPValidationError: '98.223.189.24/255.255.240.0' is not
> a valid address (hint, it's probably a network)
>
> Because, it *is* a address of a host on a network. I gave in and said:
>

10.1.2.3 is the address of a host on a network.  255.255.240.0 is a subnet
mask.

>>> net = ipaddr.IPNetwork("10.1.2.3/255.255.240.0")
>
> But then, I was dumbfounded as to how I could get the gateway IP from
> this IPNetwork object. It took me a while to figure out that you can
> iterate over IPNetwork instances:
>

Any IP address on an IP network could be the gateway, so there is no
reliable way to determine the gateway IP from the network address and subnet
mask alone.

Technicalities aside, I agree with you that IPNetwork appears to be doing
double-duty as an IPNetwork type and an IPAddressWithNetwork type, which I
find confusing.

--
Daniel Stutzbach, Ph.D.
President, Stutzbach Enterprises, LLC <http://stutzbachenterprises.com>
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