not-clos if a small object system implementation for Common Lisp.
Basic features are currently implemented
- Creating objects
- Initialization forms for variables not set at object creation
- Automatic setters and getters
- Defining methods
- It’s rather slow - I have some ideas for optimization but I’m not sure I’ll bother implementing them
- There is currently no inheritance/polymorphism
There were a few self-imposed restrictions when writing this system:
- No use of arrays - each object is an immutable list
- For this reason when an object’s value is changed a brand new modified object is created, then the symbol is rebound to that object with a macro.
- This is obviously not the most efficient way.
- No use of iteration
- Mapping to lists is used a lot
- Where there was no way around it tail-call optimized recursion was used instead.
note :tail call optimization only works on some implementations!
There is no practical reason for these restrictions, don’t look for one ;)
Short answer: you probably shouldn’t.
This was more than anything a programming exercise for me, Common Lisp already ships its great object system out of the box.
(load "not-clos.lisp")
(not-clos:make-object rectangle ((x1 0) (x2 10) (y1 0) (y2 10)))
(defvar my-rect (make-rectangle))
(rectangle-defmethod calc-area ()
(* (abs (- self-x1 self-x2)) (abs (- self-y1 self-y2))))
(format t "~a~%" (rectangle-calc-area my-rect))See ~main.lisp~ for full example.