I understood records & classes to be passed by address. I used this in my version of rtsafe in apfp.icn.
Also I got the troubles I was having with apfp to go away by changing the global I mentioned to a define. Dennis J. Darland [EMAIL PROTECTED] ----- Original Message ----- From: "Steve Wampler" <[EMAIL PROTECTED]> To: "Louis Kruger" <[EMAIL PROTECTED]> Cc: "Unicon" <[EMAIL PROTECTED]> Sent: Wednesday, October 22, 2003 4:05 PM Subject: Re: [Unicon-group] How to replace side effects efficiently? > On Wed, 2003-10-22 at 10:54, Louis Kruger wrote: > > This problem seems like another example of why Unicon could benefit from > > references types. (seems like there have been a lot of these examples > > recently) > > Careful! Icon and Unicon have gotten along pretty well for years > without reference types. While I think it deserves more discussion, > it's not clear that most of the examples aren't self-fulfilling - > there may well be equally clean ways of addressing the same issues > using other approaches. Also note, as Clint said, that there are > any number of functional languages that are also successful w/o > reference types. > > > > > Any suggestions for what actual syntax is possible for this? > > Perhaps the semantics should be discussed. > What should the behavior of the following be (also ignoring syntax > issues): > > global xref > > procedure f(a) > xref := &a > a := 3 > end > > ... > write(*xref) > and > > procedure g() > yref := &xref > *yref := &yref > write(*xref) > end > > There are reasons why functional languages don't like reference > types - they can be addressed, but it needs careful thought. > Languages like C and FORTRAN operate under a 'caveat emptor' > philosophy that isn't appropriate for languages like Unicon. > > [As an aside, back when I started teaching, I told my FORTRAN > class not to worry about breaking the computer, they couldn't > hurt it (at that time it was a multi-million dollar mainframe > used on campus for class *and* administrative work). > Well, several month later the computer center starts getting > unexpected power shutdowns on the computer - it would detect > a power failure and quickly enter a failsafe mode before > shutting itself off. They tried everything - adding a fly-wheel > generator, monitoring the power-line, etc. > > Then one day one of my students came to my office and said > "I know it sounds crazy, but every time I run my homework > assignment the computer crashes." Turns out he was passing > the constant 30 to a function that was expecting a function > reference as that argument. So the mainframe was merrily > executing a subroutine call to address 30 - which happened > to the start of the interrupt handler for power failure...] > > These days, with separate kernel and user spaces this probably > wouldn't be possible, but it was certainly embarassing at > the time!] > > -- > Steve Wampler -- [EMAIL PROTECTED] > Quantum materiae materietur marmota monax si marmota > monax materiam possit materiari? > > > ------------------------------------------------------- > This SF.net email is sponsored by OSDN developer relations > Here's your chance to show off your extensive product knowledge > We want to know what you know. Tell us and you have a chance to win $100 > http://www.zoomerang.com/survey.zgi?HRPT1X3RYQNC5V4MLNSV3E54 > _______________________________________________ > Unicon-group mailing list > [EMAIL PROTECTED] > https://lists.sourceforge.net/lists/listinfo/unicon-group > ------------------------------------------------------- This SF.net email is sponsored by OSDN developer relations Here's your chance to show off your extensive product knowledge We want to know what you know. Tell us and you have a chance to win $100 http://www.zoomerang.com/survey.zgi?HRPT1X3RYQNC5V4MLNSV3E54 _______________________________________________ Unicon-group mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/unicon-group
