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Date:	Fri, 13 Feb 2004 18:23:06 PST8
From:	Peter Skye <pskye@peterskye.com >
Reply-To:	scoug-programming@scoug.com
To:	scoug-programming@scoug.com
Subject:	SCOUG-Programming: PL/I most important statement (was: call(TZ) ? - PL/I)

Content Type: text/plain

Lynn H. Maxson wrote:
>
> I gave you the two historical reasons for the BEGIN statement.
> You offer me one unnecessary instance of its use.

Them's fightin' words.

> you want something like the following:
>
> [scurrilous setup code here, followed by . . .]
> dcl matrix (*,2) fixed dec (7,2) based(voom);
> dcl voom ptr static;
> if rotor != 0
> then do;
> allocate matrix (rotor, 2);
> .
> .
>
> The only use for the "begin" block here is to handle the
> endfile condition for the input file. There's no need
> for a "begin" block to allocate space for the matrix.

Now let me get this straight. You constantly revile the likes of C
which, if my neurons be connected this late in the day, has a memalloc()
call. You entice us mightily with the hidden persuasions of PL/I. And
then, when a daring young man (me) chooses to bypass the horrid
memalloc() call by using the most-high-level BEGIN block of PL/I, some
anti-BEGIN conjurer (you) decides it's a dastardly act indeed.

*My* code is nice and tidy and doesn't have to worry about allocations
or deallocations. *Your* code reminds me of those terrible C memallocs
which the programmer must keep track of lest he forget to release those
allocated bytes.

Throw that allocate in the trash can, Lynn. Use BEGIN.

> Before PL/Id had the "based" storage attribute it had
> "static", "automatic", and "control". You could have
> allocated ... allocate ... allocate ... deallocate ...
> continuing this process until you had exhausted the stack.
>
> In short the "allocate" statement in PL/I . . .

I'm trying to get _away_ from memory management. BEGIN takes care of
everything for me. Why use PL/I to write a C-styled program?

You're thinking too low-level. Forget about this memalloc stuff.

> you would have to have its dimension outside the "begin"
> segment and declare the matrix as an 'automatic' storage
> variable to have PL/I automatically allocate it on entry
> to the "begin" segment. All your processing of the matrix
> would have to occur within the "begin" segment as PL/I
> would automatically deallocate it upon exit, i.e. reaching
> the "end" statement for the "begin" block. I don't know
> why you would go to all this trouble when you could simply
> allocate it dynamically in the first place using either
> the "controlled" or "based" storage attribute.

That's the beauty of PL/I. While I write the program I can concentrate
on the problem to be solved, not the housekeeping required.

- Peter

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