[Python-Dev] PEP 3144 review.

[Barry Scott]

On 16 Sep 2009, at 01:05, Peter Moody wrote:

> 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.

I've seen user interfaces accept 192.168.1.1/24 as a short cut
to set the ipaddr and netmask on an interface.

For that use being able to parse that string into an IP Address and
a Net Mask is what they want.

If this is a common idiom having a utility function that returned
an IPv4Address('192.168.1.1') and IPv4Network('192.168.0.0')
would be useful.

If someone really thinks that '192.168.1.1/16' is a network any
good UI should detect it is invalid report that to the user.

If you think this is a decision that the only the caller can decide
why not add a keyword param to control the parsing?

IPv4Network( '192.168.1.1/16', syntax='loose' )

(I'm sure syntax='loose' is not right but you get the idea.)

Barry