[Twisted-Python] Idiom for database access within iterator/generator?

[Manlio Perillo]

Justin Warren ha scritto:
> Greetings twisted gurus!
> 
> I'm hoping someone with a better algorithmic brain than I could offer
> some advice on a good way to do something in a twisty/pythonic way.
> 
> The pseudocode for what I want to do is:
> 
> for item in generator_that_fetches_rows_from_database:
> 	...
> 	do_stuff()
> 	...
> 
> where generator_that_fetches_rows_from_database is an object that uses
> enterprise.adbapi (or anything else) to fetch rows from a database and
> return them to the for..in.. loop.
> 

This can be done, but you need a "pure" asynchronous PostgreSQL client.
Here is an implementation in Twisted:
http://hg.mperillo.ath.cx/twisted/pglib

Each row is processed using the IRowConsumer interface.

To keep it simple, a callback function is called for each row received 
from the backend.

Using Python 2.5 generators you can (probabily) achieve what you want.


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Manlio Perillo