Subj : Extending Pl/I
To   : David Noon
From : Murray Lesser
Date : Sun Feb 18 2001 11:20 am

(David Noon wrote to Mike Luther on 02-17-01, topic: "Language For
Multi-platfo") 

Hi David--

    (In the following, "ML>" identifies a quote from Mike Luther.)

DN>Replying to a message of Mike Luther to Murray Lesser:

DN>More interestingly, REXX is an extensible language. This means you
  >can write extension DLL's in whatever native code language you
  >fancy, provided it supports _System linkage convention. There are 
  >plenty of samples in C, and I have posted samples in PL/I 
  >and assembler. Thus, when the base language runs out of 
  >capability or too slowly, branch off into some native 
  >object code to do the fiddly bits.

     PL/I is also extensible :-).  (Almost any compiled language and
many interpreted languages are extensible with assembled procedures.  I
wrote three books in the 1980s dealing with extending various dialects
of MS BASIC compilers).  There used to be less necessity for extending
PL/I than for extending REXX, and it is much more difficult.  Extending
PL/I may have become more likely for those of us who write text-mode
utilities, now that IBM has dropped the PL/I capability to make direct
calls to the 16-bit OS/2 APIs.

DN>None of the major development tools vendors is supporting 
  >16-bit code any more, except in their assemblers. All 
  >modern compilers produce 32-bit code exclusively. The 
  >upshot is that DOS is dead. Indeed, there is no ISO/ANSI-
  >certified C++ compiler for 16-bit DOS, AFAIK. [Jonathan 
  >might know of one.] All the 16-bit C compilers are C89 or 
  >worse [K&R], with no C99 compilers available. As I said, 
  >DOS is dead.

    Hmmm.  Is that new fashion the reason IBM dropped the ability to
compile PL/I procedures calling the 16-bit bsesub.cpy OS/2 API 
functions, in FP-6?  Another loss to fashion?  I keep a copy of
the FP-4 version of my compiler in a different partition, just to avoid
having to "extend" PL/I with assembled procedures.  Once compiled, the
calls run fine under the runtime DLLs that came with FP-6.

 ML> PL/1(i), whatever, OS/2, Win-ugh, DOS .. and REXX, are they really
 ML> suitable tools for poor Mikey?

DN>It's PL/I.

DN>Only you can answer the question. How you collect 
  >background information to formulate the answer is up to 
  >you. But you have been given information from the two 
  >members of this echo who have the most experience with 
  >PL/I, and we both know/knew C too. I also know C++ quite 
  >thoroughly. And I dabble in REXX a bit, too. ... :-)

    Thanks for the kind words.  However, Mike should note that I am one
of the _only_ two members of this echo who admit to having an
acquaintance with PL/I.  If he really needs technical advice, he should
do what I do: ask you :-).

    Regards,

        --Murray
<Team PL/I>
___
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