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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Introductory Presentations, especially aimed at C++ programmers!
Date: Wed, 14 Dec 2016 16:48:30 -0600
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Xref: news.eternal-september.org comp.lang.ada:32835
Date: 2016-12-14T16:48:30-06:00
List-Id: <comp.lang.ada>

"Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org> wrote in message 
news:o2q2o6$c16$1@dont-email.me...
> On 12/13/2016 04:05 PM, Randy Brukardt wrote:
>>
>> Conclusion: I don't see any difference between Bob's version and yours in
>> terms of dynamic memory allocation needed.
>
> The difference is that, for every recursive call, the GNAT version 
> declares 2 buffers, and mine only declares 1.

...and generates a second one implicitly. Still no difference. The semantics 
of & require a copy, it can't be optimized out (with the possible exception 
of a direct assignment to something).

>From a different message of Jeff's:

>... Worrying about the efficiency of very rare situations, given the 
>general
> inefficiency of Text_IO anyway, seems like a waste of time.

Customers would disagree with you. I once had to refund a customer because 
they complained about the efficiency of our Text_IO vs. that of the similar 
C functions. I spent several weeks redoing Text_IO in part because of that 
experience (mostly so the performance of Get_Line from files is better).

It's very usual that a new customer will write a trial program with their 
shiny new compiler that just reads some text file with Get_Line. Us old Ada 
hands know better than to expect great performance from that, but one does 
not want someone's first impression of Ada to be bad. Thus the performance 
of Get_Line is one of those things that has to be optimized absolutely as 
much as possible. (One cannot get into arguments of premature optimization 
if they are returning their compiler and switching to some other 
language!!!)

                                           Randy.




                                    Randy.