Re: Disassembler
- From: "Pete Dashwood" <dashwood@xxxxxxxxxxxxxx>
- Date: Thu, 2 Mar 2006 09:00:18 +1300
"Oliver Wong" <owong@xxxxxxxxxxxxxx> wrote in message
news:MniNf.9508$vC4.5582@xxxxxxxxxxx
Excellent, Oliver. As usual a reasoned and succinct statement of the
"CG" <carl.gehr.RemoveThis@xxxxxxxxxxxxxxxxxxxxx> wrote in message
news:41d3d$4404e7ff$453db2dd$1883@xxxxxxxxxxx
Howard Brazee wrote:
I suppose you could decompile code into just about any language you
want. The more optimized the code, the more useless the decompiled
results.
You seem to insist on ignoring [or just being ignorant of] the fact that
this technology guarantees to create COBOL code that will produce exactly
the same output as the object code. In fact, I believe that the new
COBOL source, when compiled, will normally produce exactly the same
object code _assuming_ you have the same version/release/level/etc. of
the compiler that produced the original. If the code was optimized
before _and_ you indicate that the re-compile is to optimize the new
code, it will be the same. Therefore, the decompiled COBOL code is
exactly as useful or useless as it would be if you had the original
source code. If you still consider this code to be useless, then I
assume your process is always to trash every source program as soon as
you compile it. That is the essence of what you are proposing. I really
cannot understand your logic!
Source code exists not for the benefit of computers, but for the
benefit of humans. Computer would be just as happy if source code never
existed, and everything was written directly in machine code. But to give
humans an understanding of the behaviour of a program, source code is very
helpful.
For a given program behaviour, there exists multiple source codes which
will produce that exact same behaviour. Some of these source codes are
more difficult for humans to understand than others.
Howard (and others) are making the claim that if you decompile a
program, the source code you are likely to get will be very difficult for
humans to understand. In that sense, the source code is "useless" because
the main use of source code is to give understanding to humans.
See http://groups.google.ca/group/comp.lang.cobol/msg/c9afd03ff070610a
for example; this program outputs the fibbonacci sequence, but it is
difficult for a human to understand it, and thus to safely modify it.
Let's say you had a program which printed out the first 20 fibbonacci
numbers, and you wanted to update the program to print out the first 40
fibbonacci numbers instead. If you decompiled the program and got
something like the above, it'd almost be easier just to start over from
scratch.
But if you had the original source code for the 20-fibbonacci program,
and assuming it was "properly" written, it should be a relatively simple
task to modify it so it prints the first 40 fibbonacci numbers instead.
That's an example of how the original source can be useful while the
decompiled source be useless.
- Oliver
positions expressed. It is a pity that Carl was not able to catch his breath
and produce this for himself.
The problem with Evangelism is that it seems to close the ears...
Pete.
.
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