[Python-Dev] The socket HOWTO

"Martin v. Löwis" martin at v.loewis.de
Mon Jun 6 00:22:11 CEST 2011

>>> I'm not sure why the examples are good (for example, modern client
>>> code should probably use create_connection() with a host name, not
>>> connect()).
>> I disagree. create_connection is an advanced function - you shouldn't
>> be using it unless you know what it is doing.
> Can you explain? I would certainly use it myself, and I don't
> understand how it's "advanced". It's simply higher-level.

It uses getaddrinfo, which might return multiple addresses, which
are then tried in sequence. So even though it's called
"create_connection", it may actually attempt to create multiple
connections. As a consequence, it may wait some time for one connection
to complete, and then succeed on a different address.

These phenomena can only be understood when you know what it is
actually doing.

> Actually, we've been actually replacing uses of connect() with
> create_connection() in various parts of the stdlib, so that our
> client modules get IPv6-compatible.

And that's fine - the people making this changes most certainly
where capable of using advanced API.

>> No no no no no. Absolutely not.
>> a) telling people who want to learn sockets "don't learn sockets,
>>    learn some higher-level library" is besides the point. What do
>>    you tell them when they did that, and now come back to learn
>>    sockets?
> You said yourself that the HOWTO doesn't claim to explain sockets

Did I say that? If so, I didn't mean to. It explains how to use the
socket API.


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