Re: How do I write directly to a memory address?

["Randy Brukardt" <randy@rrsoftware.com>]

"Hyman Rosen" <hyrosen@mail.com> wrote in message 
news:4d6eea4d$0$14912$882e7ee2@usenet-news.net...
> On 3/2/2011 4:34 PM, KK6GM wrote:
>> Why would you assume any positive opportunity cost at all (as opposed
>> to a negative opportunity cost, that is, a savings)?  Why would you
>> assume that the entire software development/maintenance cycle is
>> cheaper when using tools and methods that produce more bugs?
>
> I assume that taking extra time to fix all known errors and to test
> very thoroughly for unknown errors will incur large costs in time,
> money, and opportunity.

That assumption depends very much on the techniques used. I very much doubt 
that "testing very thoroughly" would have much effect on software quality, 
but it surely would have the effects on time and opportunity cost that you 
are mentioning.

OTOH, if your compiler and toolset somehow eliminated most of the debugging 
phase (by detecting errors early during the "bugging" phase of program 
development), one would imagine that your costs could go way down.

Note that I think the above is a goal more than something that is completely 
achievable. I tend to think that there will always be a few logic errors 
that are too hard to detect without taking too much up-front effort. (The 
attempt of tools like SPARK to catch everything has a point of diminishing 
returns.) But we surely can do better than Ada does.

To the extent that this is possible, I already do this in my own projects. I 
hardly ever use a debugger on any of our programs (the exception is 
malfunctioning compiler output; as a compiler writer, one has to figure out 
where the generated code goes wrong, and that usually requires 
single-stepping), and testing is mostly limited to existing regression 
suites. The Ada compiler detects most problems up-front; the self-checking 
built-into the programs detects most of the rest. What's left would be 
unlikely to be detected by testing anyway (especially after clean regression 
test runs).

                                                   Randy.