> -----Ursprungligt meddelande----- > Från: IBM Mainframe Discussion List > [mailto:ibm-m...@bama.ua.edu] För Chris Craddock > Skickat: den 3 november 2009 07:39 > Till: IBM-MAIN@bama.ua.edu > Ämne: Re: An Alternative Modest PARM Proposal > > > > > > > > > > You and I have diametrically opposed perspectives of > "compatibility". > > To me, "compatibility" means the facility to call a program > from JCL > > with a long PARM presenting exactly the same interface as > today when > > it's called from other languages (such as Rexx), and requiring > > modification neither of the target program nor of the > calling language > > (i.e. Rexx). You seem to advocate that the interface when > called from > > JCL should differ from the interface when called from Rexx, etc. > > I can't view that as "compatible". > > > > Yes, some programs would break if they could be called from > JCL with > > long parms, identically as they'd break if called from > Rexx, etc. with > > the same parms. Even that identical behavior in breakage > is a form of > > compatibility. > > > > > The PARM interface is older than dirt and even though we can > all agree with hindsight that it was a momentously stupid > design, it is nevertheless a formal, documented interface and > literally thousands of badly written programs work correctly > ONLY because the initiator is never going to give them a > parameter string of more that 100 characters. That's the one > and only interface contract. The assertion that you can find > programs that behave well when called directly with longer > parameter strings is also true, but completely uninteresting. > > Changing the behavior of PARM is fraught with > incompatibilities. So much so that wiser heads elected not to > pull the trigger on it. There are lots of ways of enabling > (much longer) parameter strings but they all necessarily > involve defining some brand new and non- overlapping > interface definition. New programs written to the putative > new parameter interface spec will work correctly and > completely oblivious of the old spec. And since the existing > PARM interface will remain unchanged, all old programs will > continue work as they do now, completely oblivious of any new > interface. > > THAT my friends is compatibility. Not elegant, not pretty, > but guaranteed compatible. Now can we all just get over this nonsense?
Tsk, tsk. I think You should leave this matter to more persons with more knowledge. You see, this is a complicated matter, which You will maybe grasp when You have got some experience. Regards, Thomas Berg __________________________________________ Thomas Berg Specialist IT-U SWEDBANK ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
