[Python-Dev] _socket efficiencies ideas

Guido van Rossum guido@python.org
Wed, 09 Apr 2003 11:20:39 -0400

> > I still don't understand why intercepting the all-numeric syntax
> > isn't good enough, and why you want a <numeric> prefix.
> >
> I guess intercepting all numeric is OK, it is just less efficient
> (since it requires a trial parsing of an address, which is wasted if
> it is not all numeric), and because it is so easy to implement
> <numeric>.

The performance loss will be unmeasurable (parsing a string of at most
11 bytes against a very simple pattern).  Compare that to the true
cost of adding <numeric>: documentation has to be added (and dozens of
books updated), and code that wants to use numeric addresses has to be

> However, all my operational goals are achieved if the
> old check for pure numeric is reinstated at the lowest level
> (probably in getsockaddrarg in socketmodule.c), so it is used
> everywhere.


> > The reason I'm reluctant to add a new notation is that AFAIK it would
> > be unique to Python.  It's better to stick to standard notations IMO.
> > <broadcast> was probably a mistake, since it seems to mean the same as
> > (for IPv4).

> I accept this logic.  However, python is hiding a very useful (for 
> efficiency) piece of the API, or depending on guessing whether you want 
> it or not by looking at the format of an address. There are times in 
> higher-level (python) code where getaddrinfo  is called to get a CNAME, 
> where I would also like to cause the raw IP to be returned by force, 
> instead of attempting to get a CNAME, since I already know, by the IP I 
> chose, that one doesn't exists.  If we make the same check for numeric 
> IPs in getaddrinfo, then it becomes impossible to resolve numeric names 
> back to real ones.  There is not way for getaddrinfo to know which way 
> we want it, since in this case both ways might be needed.

You're right, this functionality should be made available.  IMO the
right solution is to make it a separate API in the socket module, not
to add more syntax to the existing address parsing code.

--Guido van Rossum (home page: http://www.python.org/~guido/)