Python generators (coroutines)

Diez B. Roggisch deets at nospam.web.de
Wed Apr 23 16:34:11 CEST 2008


rocco.rossi at gmail.com schrieb:
> I would really like to know more about python 2.5's new generator
> characteristics that make them more powerful and analogous to
> coroutines. Is it possible for instance to employ them in situations
> where I would normally use a thread with a blocking I/O (or socket)
> operation? If it is, could someone show me how it can be done? There
> appears to be a very limited amount of documentation in this repect,
> unfortunately.

What do you mean by "new generator characteristics"? AFAIK generators 
have been around at least since python2.3. Newer versions of python 
include things like generator expressions (since 2.4 I believe).

However, generators don't help anything in blocking IO-situations, 
because they rely on co-operatively re-scheduling using yield.

Of course you could try & use non-blocking IO with them, but I don't see 
that there is much to them.

Or you could go & use a single poll/select in your main-thread, and on 
arrival of data process that data with generators that re-schedule in 
between so that you can react on newer data. Depending on your scenario 
this might reduce latency.

Diez



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