On 4/6/2012 9:53 AM, Sam Siegel wrote:
On Fri, Apr 6, 2012 at 8:45 AM, Phil Smith<p...@voltage.com> wrote:
Darn it, no matter what I've tried, I CANNOT get PL/I to handle a plist
[what I'd call] normally-marking the high bit on the last specified
parameter. If I use OPTIONAL, I get all the parameters, with zeroes for the
ones that were omitted. That's not right, because I can't tell whether they
were omitted or specified as zero.
Ideas??
When using OPTIONAL, isn't the address in the parmlist set to zero instead
of a valid address? Said differently, if the address in the parmlist is
zero, the associated parameter is not available.
But his dilema is that in C data itself may be passed in the parmlist; now
the dilema: is a pointer of zeros (address of parm is NULL) an indicator
of an omitted argument or a deliberate pass of a value of zeros. There
is no magic way for anyone to know: you have to establish conventions
and protocols to make these distinctions. And with the latest compilers
this conundrum exists in Assembler, COBOL, PL/I and C.
Adding flexibility always comes at a price of added complexity or
potential ambiguity (or both), right?
--
...phsiii
Phil Smith III
p...@voltage.com<mailto:p...@voltage.com>
Voltage Security, Inc.
www.voltage.com<http://www.voltage.com>
(703) 476-4511 (home office)
(703) 568-6662 (cell)
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