[Stackless] Re: [Zope-dev] Zope 2.7 running with Stackless 3.0

[Shane Hathaway]

[I'm sorry, Aaron Watters, that you thought I was leading Chris on.  I'm 
only trying to cheer up Chris and help him get back on his feet.  Now 
back to the Stackless discussion.]

Bob Ippolito wrote:
> On Wednesday, Sep 3, 2003, at 16:12 America/New_York, Jim Bowery wrote:
> 
>     Someone who thinks there should be more allowance for indeterminate
>     order of evaluation in highly threaded applications.
> 
> 
> Twisted ( http://www.twistedmatrix.com/ - website might still be moving 
> though ) does this to an extent with Deferreds (aka promises/futures, I 
> think), but it's based on a single threaded reactor pattern (with 
> threads/threadpools if you need them for specific tasks) and doesn't 
> have the luxury of stackless to speed up and simplify things. Each 
> Deferred object is a chain of callback/failure pairs, but they're not 
> transparent. Acquiring the value or failure from a Deferred is only 
> possible through the callback/errback callback chain, it will never 
> morph into the value object if you try and use it like one (not 
> transparent). This is good and bad, but it can be done with mainline 
> Python without new syntax or even generators (when you use generators 
> with Deferreds you pretty much go back to synchronized land, so they're 
> not good for much other than syntax in Twisted).

As I see it, Twisted goes to great effort to make it possible to defer 
all I/O to a reactor.  Stackless practically eliminates the difficulty 
of doing that.  Therefore, if Twisted used Stackless, Twisted would be 
significantly simpler and probably faster.

FWIW... I came to understand this concept when generators were added to 
Python.  At first, I wondered by anyone thought they were useful; after 
all, you can do exactly the same thing by writing a class instead of a 
function and storing all state as instance attributes.  Then I saw how 
much simpler and shorter a generator could be.  I realized that the 
transformation from generator to class is very similar to the 
transformation from synchronous I/O to asynchronous I/O.  Wouldn't it be 
nice to be able to write synchronous code, then use it asynchronously? 
Yay Stackless!

Shane

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