Re: Ada and Unix--Blocked Tasks

[cis.ohio-state.edu!zaphod.mps.ohio-state.edu!sdd.hp.com!news.cs.indiana.e]

In article <1991Aug2.181729.28061@sctc.com>, stachour@sctc.com (Paul Stachour)
writes:

>        [some stuff deleted]
>    Doing the system-specific, unix-style signals seems to me to
> be at odds with doing things in Ada with tasks, yes?
> 
>    Which leads us to the basic question:
> 
>      If the Ada system you are using can't do tasking "correctly"
> (i.e., in a non-blocking way) in its implementation, what is in
> error?
> 
>    Is it the OS (unix in this case)?
>    Your Ada compiler vendor (Don't know who)?
>    Your Ada run-time vendor?
>    Or something else?

Questions of this nature (or rather, the nature of the ORIGINAL question)
always make me make the "system-specific knowledge" lecture to my students. 
I'm often asked things like "how does Ada do print spooling" or "how does Ada
handle VT100-style screen control (or mouse movement, etc.)".

I think it's important for designers & programmers of ANY language to remember
what capabilities are controlled by language constructs, and either 
(a) confine the solution to the "domain" of the language capability, or 
(b) realize what portions of the solution are affected by "external controls"
(relative to the language and it's run-time specific support) and act
(implement) accordingly.

Paul's questions are logical ones when trying to DETERMINE the domain of the
implementation "problem", but we as software engineers should attempt to be as
knowledgeable as possible regarding BOTH the language and the environment so
that lengthy problem research/determination is avoided.

Ray
-----
Ray Harwood           |Data Basix           |Associate Faculty,    
Voice: (602)721-1988  |PO Box 18324         |   Pima Community College
FAX:   (602)721-7240  |Tucson, AZ 85731     |Instructor in Ada and Pascal
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