Re: Java vs Ada 95 (Was Re: Once again, Ada absent from DoD SBIR solicitation)

[nasser@apldbio.com]

In article <Dz8znD.Fpt@thomsoft.com>, kst@thomsoft.com says...
>
>In another article, Robert Dewar wrote, "The whole point of gc is that
>it has no semantics, it is transparent!"  I don't think that's quite
>true either.  For example, consider the following Ada program:
>
>    with System;
>    with Ada.Text_IO; use Ada.Text_IO;
>    procedure GC_Test is
>	type Pointer is access Integer;
>	P : Pointer;
>    begin
>	for I in 1 .. System.Memory_Size loop
>	    P := new Integer;
>	end loop;
>	Put_Line("The system has garbage collection");
>    exception
>	when Storage_Error =>
>	    Put_Line("The system does not have garbage collection");
>    end GC_Test;
>
>For simplicity, I've assumed here that System.Memory_Size fits in an
>Integer and that the compiler doesn't optimize out the allocation in
>the loop; there are ways around that.
>
>It's true that garbage collection is semantically transparent for
>well-behaved programs (i.e., ones that wouldn't otherwise run out of
>memory and don't try to play certain nasty tricks).
>


Are you saying that the compiler will generate code (assuming
GC is supported) to free the memory pointed to by P before it 
does the next allocation? (that's why the program does not
run out of memory in this loop).

To me, this program is an erroneous program to start with. Having 
GC will only HIDE this fact. So having GC seems not such a good idea, 
since programmers will start writting sloppy code saying the GC will
take care of the memory.

So, based on this new radical point of view of mine, I would say that a
well written program should not need GC. If each function/package cleans
after itself, and the programmer is careful, then there is no need
for GC. Programs that have memory leakage are programs that defective, and
so one should fix them, GC is not the solution, the solution is to go
fix the code itself instead, wich would eleminate the need to having GC
to start with.  Here, I just solved this GC issue once and for all.


Nasser