Re: [racket] question about classes

2012-05-20 Thread Joe Gilray
Hi Matthias, Thanks for the lesson and the reformatting too. I had thought that the "(module... " format was needed... it's nice to get back that indent. In case you're intestered, here some of my uses of these continued fraction classes: First a use of gencontfrac% ; repeat procedure for cont

Re: [racket] question about classes

2012-05-20 Thread Matthias Felleisen
On May 20, 2012, at 11:02 AM, Joe Gilray wrote: > 1) Is what I've done an abomination? Am I simply abusing inheritance? You are changing a part of a recursive nest of methods, which is what inheritance is all about. > 2) To make the code below work, I had to make expand-repeat public as I

Re: [racket] question about classes

2012-05-20 Thread Joe Gilray
Hi Matt, Thanks, what you wrote makes perfect sense (of course... that's what I get for programming at such hours!) Anyway, working code included below and the main purpose of learning about classes in Racket helped along the way. To take a step back and look at what I've "accomplished" in this

Re: [racket] question about classes

2012-05-20 Thread Matthew Flatt
The problem is that `start' doesn't get a value for a `sqrtcontfrac%' instance until `super-new' in `sqrtcontfrac%' is evaluated. But the expression for the second argument in `super-new' calls `build-repeat', so that `build-repeat' tries to use `start' before it has a value. I'm not sure of the s

[racket] question about classes

2012-05-20 Thread Joe Gilray
I'm trying to learn to use classes in Racket. I did some successful simple experiments then moved on to inheritance. When I try to use the code below, the following code: (new sqrtcontfrac% [sqrval i]) leads to the message: sqr: expected argument of type ; given # Why isn't start being inherit