Re: wait does not perform as expected

[Niklas Holsti <niklas.holsti@tidorum.invalid>]

On 2023-02-23 20:47, Daniel Gaudry wrote:
> On Thursday, February 23, 2023 at 7:29:36 PM UTC+1, Niklas Holsti wrote:
>> On 2023-02-23 20:14, Dmitry A. Kazakov wrote:
>>> On 2023-02-23 18:35, Niklas Holsti wrote:
>>>> On 2023-02-23 16:26, AdaMagica wrote:
>>>>> Niklas Holsti schrieb am Mittwoch, 22. Februar 2023 um 18:36:06 UTC+1:
>>>>>> On my system, Get_Immediate does /not/ use the inputs collected (but
>>>>>> not
>>>>>> "consumed") by Look_Ahead, but instead checks if there are _new_ input
>>>>>> keystrokes. If there are none, Get_Immediate returns "not Available"
>>>>>> (Hit is False) and so the loop continues.
>>>>>
>>>>> Are you sure?
>>>>
>>>> That is what I observe.
>>>
>>> The implementation of Look_Ahead calls getc followed by ungetc. Thus it
>>> blocks until an input if there is no buffered. And not just input, but
>>> for a line or file end.
>> That seems in order.
>>
>> However, the crux of the question is in Get_Immediate. Do you know how
>> that is implemented on various systems? It has to disable line buffering
>> and line editing on the input stream. One question is whether and how
>> such "tty" configuration changes affect whatever buffers getc/ungetc use.
>>
>> On my system, if Look_Ahead uses getc and ungetc, it seems Get_Immediate
>> does not use the same buffers, and has no effect on those buffers. That
>> could be desirable behaviour in some cases, undesirable in others.
>>
>> On AdaMagica's system, it seems that Get_Immediate uses the same buffers
>> as Look_Ahead (getc/ungetc).
> 
> 
> Hi,
> On my ubuntu system the
> ada.text_io.GET_IMMEDIATE(ITEM => CHAR, AVAILABLE => HIT);
> just pause the program regardless of any key being hit.
> I just cannot use a wait  (several shorts one in a row) interrupted by a key hit.
> Any possibility you may know of ??


Please show the Ada code you have now. I assume there is no Look_Ahead 
there, right?

Best if you can write, test and post a short, stand-alone program that 
just contains the wait-for-keystroke procedure, then we can be sure that 
there is nothing else in the program that might interfere.