[Twisted-Python] Event Driven Programming 101 question
m at moshez.org
Sat Aug 2 07:01:46 EDT 2003
On Sat, 2 Aug 2003, Steve Freitas <sflist at ihonk.com> wrote:
> It's apparent to me that a lot's going on
> behind the scenes between Deferreds and the Reactor
Nope. There's very little magic going on.
> When is a Deferred guaranteed to have a result?
> One answer could be, "When its callback gets called." And that would be true.
> But what if the function that gets the Deferred needs the result before it
> can move on?
It's out of luck.
> def xmlrpc_foo(self):
> result = dbpool.runQuery("select * from gigantic_table") # adbapi
> return result
This "just" works. When xmlrpc_foo returns a result, the Twisted XMLRPC
machinery checks if it is a deferred. If it is, it won't send a result
back to the client until the deferred is triggered.
Here is the code in question, just to see how little magic there is:
[_ebRender and _cbRender do the work of actually formatting the response]
Moshe Zadka -- http://moshez.org/
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Riley: Yeah, a lot of young people nowadays are experimenting with shortness.
Agile Programming Language -- http://www.python.org/
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