[Python-ideas] Async API: some code to review

Yury Selivanov yselivanov.ml at gmail.com
Mon Oct 29 17:47:50 CET 2012

On 2012-10-29, at 12:07 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:

>> To invoke a primitive I/O operation, you call the current task's
>> block() method and then immediately yield (similar to Greg Ewing's
>> approach). There are helpers block_r() and block_w() that arrange for
>> a task to block until a file descriptor is ready for reading/writing.
>> Examples of their use are in sockets.py.
> That's weird and kindof ugly IMHO. Why would you write:
> 	scheduling.block_w(self.sock.fileno())
>        yield
> instead of say:
>        yield scheduling.block_w(self.sock.fileno())
> ?

I, personally, like and use the second approach.  But I believe the 
main incentive for Guido & Greg to use 'yields' like that is to make
one thing *very* clear: always use 'yield from' to call something.  
'yield' statement is just an explicit context switch point, and it 
should be used only for that purpose and only when you write a 
low-level APIs.


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