Re: Get_Immediate warning, (was: How to get a character?)

[Robert Dewar <robert_dewar@my-dejanews.com>]

In article <87zp4aud4a.fsf@bglbv.my-dejanews.com>,
  bglbv@my-dejanews.com wrote:
> Robert Dewar <robert_dewar@my-dejanews.com> writes:
>
> > In article <87hfqkgnrm.fsf@bglbv.my-dejanews.com>,
> >   bglbv@my-dejanews.com wrote:
> >
> > > The standard is clearly written under the assumption
that
> > > interactive input isn't normally buffered more than
one
> > > line at a time, but this doesn't seem to be even an
> > > Implementation Advice, much less a requirement.
> >
> > That's quite wrong.
>
> Sorry, I should have been more specific: the description
> of Text_IO in the standard is written under the
> assumption...

Nope, the most you can say is that the addons (get
immediate and flush) are written with this assumption.
But these are addons to a largely unchanged spec that
was written with NO thought of interactive IO at all.

> I'll support my claim by pointing you to the last
> sentence in A.10(2) which talks of "an end-of-line to
> signal availability". It does so in such a casual way
> that I would not construe that remark as normative; but
> as an indication of what the authors had in mind I
> find it excellent.

But that sentence *is* one of the glued on sentences.
Just compare this para with RM83 (14.3(2)).

> > Ada 83 standard is written that way, and the Ada 95
> > standard copies the definitions, adding only Flush and
> > Get_Immediate, both of which are pretty much completely
> > implementation dependent.
>
> "Pretty much completely" isn't a technical term either,
> is it?

I have defined this precisely by showing you EXACTLY what
the RM has to say that is normative about these functions.
We *do* know that Get_Immediate gets a character, so it
is not *completely* implementation dependent, but that's
EXACTLY the uninteresting part of Get_Immediate, what is
interesting is *how* it gets it, and this is left as ID.
That's *exactly* what I meant by PMCID :-)

THe problem of Text_IO in interactive environments is
well understood, and it was a quite deliberate decision
NOT to try to address it in the Ada 95 design. The general
feeling was that it was too broken to get exactly right,
and not broken enough to be worth a major kludging up.
At the last minute the Get_Immediate and Flush bandaids
were applied to stop the patient from bleeding to death :-)
But plastic surgery was beyond the budget!


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