[usocket-devel] Problem with :ready-only

[Chun Tian (binghe)]

Notice: All "READ-ONLY" in past mail should be "READY-ONLY".

--binghe

在 2010-6-28，23:48， Chun Tian (binghe) 写道：

> Hi, Daniel
> 
> I'm very sorry for the late response for your multiple posts on the :READY-ONLY keyword argument of WAIT-FOR-INPUT.
> 
> The short answer for you will be: always use (:READY-ONLY T), and ...
> 
> here is an formal answer from the original designer of WAIT-FOR-INPUT, Erik Huelsmann:
> 
> """
> Without the READ-ONLY arg, WAIT-FOR-INPUT will return all sockets in
> the original list you passed it. This prevents a new list from being
> consed up. Some users of USOCKET were reluctant to use it if it
> wouldn't behave that way, expecting it to cost significant performance
> to do the associated garbage collection.
> 
> Without the READ-ONLY arg, you need to check the socket STATE slot for
> the values documented in usocket.lisp in the usocket class:
> 
> (state
>   :initform nil
>   :accessor state
>   :documentation "Per-socket return value for the `wait-for-input' function.
> 
> The value stored in this slot can be any of
> NIL          - not ready
> :READ        - ready to read
> :READ-WRITE  - ready to read and write
> :WRITE       - ready to write
> 
> The last two remain unused in the current version.
> ")
> """
> 
> In my opinion, this design is reasonable: for performance critical USOCKET applications, programmers should use (:READY-ONLY NIL), the default option, and check the status of each usocket in the waiting list, this prevents unnecessary runtime consing. For simple use, (:READY-ONLY T) is very convenient, you can just found which usocket is readable just from the return value (as a list) of WAIT-FOT-INPUT.
> 
> I hope this mail could solve your confusion.
> 
> Regards,
> 
> Chun Tian (binghe)
> 
> 在 2010-5-4，06:05， Daniel Weinreb 写道：
> 
>> Hi. I just tried out the latest usocket.  It's not working
>> properly for me, because wait-for-input returns true
>> even when there isn't any input.
>> 
>> If I change the default value of the :ready-only argument to
>> wait-for-input to t instead of nil, that fixes the problem.
>> 
>> I don't even understand why this argument
>> exists; no caller seems to pass it at all!  What's going
>> on here?
>> 
>> Thanks.
>> 
>> -- Dan
>> 
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>