Seems like this might be an excuse to correct what I view as a historical
mistake in the Assembler, namely the precedence of native
instructions/extended mnemomics over macros. This precedence means that
every time IBM introduces a new instruction or extended mnemonic they
introduce a backward incompatibility and risk breaking someone's code.
This is bad for customers and bad for IBM as it paints them into a corner
where they're afraid to add stuff because of the backward compatibility
issues.
I understand that there might be implementation issues -- I suspect that
the assembler doesn't currently scan all macro libraries and build a
look-aside table of all macros in those libraries, a technique that would
probably be required to allow macro precedence over native
instructions/extended mnemonics. I also understand that additional
controls would be required so that system macros, say, could insist on
getting native instructions rather than macros, but this doesn't seem
daunting. There also might be an issue of grandfathering existing
instructions -- it wouldn't surprise me if someone somewhere has a dead
LLGF or whatever macro laying around in some library somewhere, just
waiting to pounce. Again, controls over what level of instructions have
precedence over macros wouldn't be a daunting thing to implement.
Whether any of this is worth it depends on one's view of the assembler. If
the view is that it's gone about as fer as it can go, and there aren't
likely to be any/many new instructions/mnemonics then none of this is
worth the trouble. If, on the other hand, the view is that there will be a
steady trickle of new instructions/mnemonics over the course of the next
10 years, maybe it's worth slaying this precedence dragon once and for all.
On Sun, 17 Mar 2013 02:33:24 -0400, Shane G <[email protected]> wrote:
I think a SHARE requirement would be a useful start to discussing
additional extended mnemonics. I'd follow that up with a HLASM RFE
request.
I must admit to being somewhat bewildered as to what prompted Ed to
initiate
this discussion at all. As John E intimated, I reckon this cat has well
and
truly scarpered.
_everybody_ will have different (lack of) standards for this ...
Shane ...
--
Alex Kodat
Senior Product Architect
Rocket Software
t: +1 781 684 2294 • m: +1 315 527 4764
e: [email protected] • w: www.rocketsoftware.com
