Path: utzoo!attcan!uunet!lll-winken!lll-tis!helios.ee.lbl.gov!pasteur!ames!mailrus!utah-gr!uplherc!sp7040!obie!wsccs!terry
From: terry@wsccs.UUCP (Every system needs one)
Newsgroups: comp.lang.c
Subject: Re: VMS C  &  records in files
Summary: Not if you have a preprocessor
Message-ID: <624@wsccs.UUCP>
Date: 31 Aug 88 05:15:35 GMT
References: <196@rna.UUCP> <6671@bloom-beacon.MIT.EDU> <1609@edison.GE.COM> <644@eplrx7.UUCP>
Lines: 45

In article <644@eplrx7.UUCP>, ward@eplrx7.UUCP (Rick Ward) writes:
> On a related note, why couldn't Digital have made it easier to call system
> functions from C.  This difficulty alone makes C unusable on VMS, at least 
> in my opinion :(.  The problem is that you have to allocate and build 
> structures describing each variable you want to pass to a system routine.
> YUCK!

Not if your C has #include or #define... it does, doesn't it?

#include <descrip.h>

...
...
...

$DESCRIPTOR( foo, "whatever");

makes a descriptor foo.

As far as modding a descriptor struct, once built, the most common
problem is that you need a sizeof() op, and that's a preprocessor
thing and you can't pass it to your function to fill the descriptor
without being kludgy.  Observe:

#define filldesc( x, y) magicfilldesc( x, y, sizeof(y))

	filldesc( desc, "hello");


magicfilldesc( desc, object, size)	/* VMS enjoys long names*/
{
...
...
...
}

Admittedly, it makes for some verbose assembly, but what can you expect
from a converted optimising PL/1 compiler anyway?


| Terry Lambert           UUCP: ...{ decvax, ihnp4 } ...utah-cs!century!terry |
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