Re: Is the Writing on the Wall for Ada?

[Marin David Condic <nobody@noplace.com>]

Really interesting, but not necessarily compeling.

If all I'm basically after is some particular user input that I intend 
to store and/or process in some semi-insignificant way, a few extra 
miliseconds is probably unnoticable. ("I got your input. Thanks. I'll 
check it for validity and then go store it for you. See you later... 
Bye!") How is anybody going to know the difference? Maybe in some apps 
that are *really* heavy into string parsing, it might make a difference 
big enough to matter. (5 minutes per batch-compile versus 10 minutes per 
batch compile?) But usually - even in that case - the answer "buy a 
bigger computer" tends to be cheaper than "go make your programmers 
optimize it to save me some time..."

I'm not saying you're wrong. Just that in most practical circumstances, 
nobody cares. Hence, the question: "Does anybody really need 
Bounded_String?"

MDC



tmoran@acm.org wrote:
> 
>     Liking numbers, I tried some timings on three different Ada compilers.
> The results are all over the map.
> 
>   s1 : string(1 .. 10);
>   s2 : string(1 .. 100);
>   abs1 : bs1.bounded_string; -- length 10
>   abs2 : bs2.bounded_string; -- length 100
>   u : ada.strings.unbounded.unbounded_string;
>   test : constant string := "12345";
>   cabs1 : bs1.bounded_string:=to_bounded_string(test);
>   cabs2 : bs2.bounded_string:=to_bounded_string(test);
>   cu : ada.strings.unbounded.unbounded_string:=to_unbounded_string(test);
> 
> Each column represents a different compiler.  The numbers are times for a
> million iterations, divided by the total for that compiler, so each column
> sums to the same value (within rounding).  So the first row shows that
> assigning a 5 character string to another 5 character string is among the
> fastest things each compiler can do.  Compiler A and C are at their
> slowest doing "&" of unbounded strings, while B's slowest is "&" of
> bounded strings.
> 
>  A       B      C
> 0.01    0.01   0.01   s1(1 .. 5) := test
> 0.01    0.00   0.01   s1(1 .. 5) := test;
> 0.02    0.01   0.00   s2(1 .. 5) := test;
> 0.20    1.86   0.25   abs1 := bs1.to_bounded_string(test);
> 2.49    2.13   0.63   abs2 := bs2.to_bounded_string(test);
> 1.98    3.25   7.69   u := ada.strings.unbounded.to_unbounded_string(test);
> 
> 0.24    0.06   1.17   s1(1 .. 10) := s1(1 .. 5) & s1(1 .. 5);
> 0.24    0.06   1.16   s2(1 .. 10) := s2(1 .. 5) & s2(1 .. 5);
> 1.10    3.84   0.28   abs1 := cabs1 & cabs1;
> 4.00    4.18   0.70   abs2 := cabs2 & cabs2;
> 5.89    3.70   7.95   u := cu & cu;
> 
> 0.01    0.01   0.00   if s1 = test then junk:=true;end if;
> 0       0.00   0.00   if s2 = test then junk:=true;end if;
> 0.31    0.04   0.08   if abs1 = test then junk:=true;end if;
> 0.32    0.03   0.07   if abs2 = test then junk:=true;end if;
> 0.31    0.05   0.09   if u = test then junk:=true;end if;
> 
> 0.48    0.03   0.06   if abs1 = cabs1 then junk:=true;end if;
> 0.54    0.03   0.06   if abs2 = cabs2 then junk:=true;end if;
> 0.02    0.05   0.08   if u = cu then junk:=true;end if;
> 
> 0.40    1.23   0.64   s1(1 .. 5) := slice(abs1,1,5);
> 1.30    1.26   0.66   s1(1 .. 5) := slice(u,1,5);
> 0.03    0.06   0.03   abs1 := cabs1;
> 0.37    0.16   0.21   abs2 := cabs2;
> 0.35    0.78   2.35   u := cu;
> 
> 0.63    0.78   0.74   si:=index(s1,test);
> 3.51    0.78   2.48   si:=index(s2,test);
> 0.48    0.83   0.60   si:=index(abs1,test);
> 0.48    0.82   0.62   si:=index(abs2,test);
> 0.70    0.81   0.58   si:=index(u,test);
> 
> 0.81    1.24   1.82   if length(u) < 100 then append(u,'x');else u := cu;end if;
> 3.52    2.69   0.10   if length(abs2)<100 then append(abs2,'x');else abs2:=cabs2;end if;


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Marin David Condic
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