[Stackless] Stackless API
oren-slp at hishome.net
Mon Feb 2 21:13:45 CET 2004
On Mon, Feb 02, 2004 at 02:13:05PM -0500, Bob Ippolito wrote:A
> Personally I'm -1 on renaming things. If you want compatibility with
> existing code, don't change the semantics of stackless. Instead, make
> a channel-wrapper or subclass that adopts the particular interface that
> you want (consumer, generator, semaphore, whatever).
All Python builtins support iteration if it makes sense in some way
for that type. I think channels should, too. Users would expect to be
able to write something like "for item in channel".
You don't have to rename - add a next() method as a synonym for receive.
Just like in Python 2.3 a file object's next() method is more-or-less a
synonym for readline().
> I think that exceptions on channels are more useful than just closure
> notification, but I think the implementation should be changed to make
> these exceptions travel out-of-band from the data.
An easy way to implement that is to create an internal wrapper object for
exceptions. An instance of this wrapper will be created by send_exception()
and receive() will check if the object is an instance of this type. Sending
an exception will be slightly slowed down by creating the wrapper object but
the more critical path of receiving will actually be faster: a call to
PyObject_IsInstance can be replaced with a direct test of result->ob_type
because the wrapper is not subclassable. In fact, it's never visible to
The wrapper could also carry an optional traceback. Existing code that uses
send() and send_exception() consistently should continue to work with no
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