Re: Using Global Variables

[crispen <@ada3.ca.boeing.com:crispen@efftoo.boeing.com>]

sampson@cod.nosc.mil  (Charles H. Sampson) says:

>     Several of the entries in this thread have raised the spectre of shared
>memory.  Without addressing whether shared memory is good or bad, let's clar-
>ify that it's not the point of this thread.

Mea culpa, inter alia.  I keep thinking of the way that global visibility
is implemented (as memory).  And if you've got any sort of tasking or 
multiprocess considerations you have at least the possibility of
shared memory.  So I apologize for going from point A to point Q
without touching the bases in between, and for my part in broadening
the topic.

You are certainly right that communication between elements within a
process and communication between processes are two separate things.
I do think, though, that there are global visibility issues for both.
And I think that people writing on this topic were addressing both.

For example:

Larry Howard  (lph@sei.cmu.edu) says:

>There may also be considerable power in other forms of coordination, even if
>these same forms have been misused in the past.  I think we should only insist
>that whatever is used be understandable and predictable.

Right on!  I'm not sure I completely accept your notion of "decoupling
communication from invocation or synchronization" but I agree that
"previous offenders" should be given a chance to rehabilitate themselves.

I know that you believe that there are software architectures that
can standardize and template-ize the use of global variables to such an
extent that the practice becomes safe.  I think I do, too.  What I
do wonder about is the non-abstract use of memory (potentially
shared memory in a multiprocess system) to implement global variables.
That's the part I have concerns about.

It feels to me like we've taken our "previous offender", locked him
in a room with only a couple of doors in and out (which we can watch)
but he's (potentially) using the phone to commit crimes.
 
>I guess what I really objected to in this thread was the odor of orthodoxy
>when (IMHO) we still seem to be on a fairly steep learning curve.
 
Double right on!  And another mea culpa if my pedantic style was
mistaken for assurance about my views.  I am presently only sure that
I have doubts.
+-------------------------------+--------------------------------------+
| Bob Crispen                   |     Down with orthodoxy, or DIE!     |
| crispen@foxy.boeing.com       +--------------------------------------+
| (205) 461-3296                |Opinions expressed here are mine alone|
+-------------------------------+--------------------------------------+