Lisp newbie here. I'm trying to program a simple spreadsheet - it is a
2D array made up of cells.
Here's the code I've got:
(defclass cell ()
((value :accessor cell-value
:initform nil
:initarg :value)
))
(defmethod set-cell-value ((acell cell) new-value)
(setf (cell-value acell) new-value))
(defgeneric print-cell-value (cell))
(defmethod print-cell-value ((acell cell))
(format t "~A " (cell-value acell)))
(defparameter acell (make-instance 'cell))
(set-cell-value acell 23)
(print-cell-value acell)
(defparameter *sheet* (make-array '(13 6) :initial-element 'cell))
(defun num-rows (sheet)
"Return the number of rows in a sheet"
(car (array-dimensions sheet)))
(defun num-cols (sheet)
"Return the number of columns in a sheet"
(cadr (array-dimensions sheet)))
(defun get-row (sheet n)
"Return the nth row (>=0) of a sheet"
(loop for c from 0 to (1- (num-cols sheet))
collect (aref sheet n c)))
;(print (get-row *sheet* 1))
(defun print-row (sheet n)
(let ((row (get-row sheet n)))
(mapcar #'print-cell-value row)))
(print-row *sheet* 1)
The class cell will become more complicated as I add in functionality.
At the line
(print-cell-value acell)
it prints 23, as expected.
But when it gets to
(print-row *sheet* 1)
it print out
debugger invoked on a SIMPLE-ERROR in thread #<THREAD "initial thread"
{A806741}>:
Error during processing of --eval option (LOAD #P"sheets.lisp"):
There is no applicable method for the generic function
#<STANDARD-GENERIC-FUNCTION PRINT-CELL-VALUE (1)>
when called with arguments
(CELL).
What am I doing wrong?
···········@yahoo.co.uk wrote:
> Lisp newbie here.
Omigod, they're everywhere. Well, if the Tilton Conjecture is correct
with schools reopening this summer plague of newbies should turn into...
hang on, it's my agent. Something about O'Reilly needing books fast on
some new language....
> I'm trying to program a simple spreadsheet - it is a
> 2D array made up of cells.
>
> Here's the code I've got:
>
> (defclass cell ()
> ((value :accessor cell-value
> :initform nil
> :initarg :value)
> ))
>
> (defmethod set-cell-value ((acell cell) new-value)
> (setf (cell-value acell) new-value))
>
> (defgeneric print-cell-value (cell))
> (defmethod print-cell-value ((acell cell))
> (format t "~A " (cell-value acell)))
>
> (defparameter acell (make-instance 'cell))
> (set-cell-value acell 23)
> (print-cell-value acell)
>
>
>
> (defparameter *sheet* (make-array '(13 6) :initial-element 'cell))
>
> (defun num-rows (sheet)
> "Return the number of rows in a sheet"
> (car (array-dimensions sheet)))
>
> (defun num-cols (sheet)
> "Return the number of columns in a sheet"
> (cadr (array-dimensions sheet)))
>
> (defun get-row (sheet n)
> "Return the nth row (>=0) of a sheet"
> (loop for c from 0 to (1- (num-cols sheet))
> collect (aref sheet n c)))
> ;(print (get-row *sheet* 1))
>
>
> (defun print-row (sheet n)
> (let ((row (get-row sheet n)))
> (mapcar #'print-cell-value row)))
>
> (print-row *sheet* 1)
>
>
> The class cell will become more complicated as I add in functionality.
> At the line
> (print-cell-value acell)
> it prints 23, as expected.
>
> But when it gets to
> (print-row *sheet* 1)
> it print out
>
> debugger invoked on a SIMPLE-ERROR in thread #<THREAD "initial thread"
> {A806741}>:
> Error during processing of --eval option (LOAD #P"sheets.lisp"):
>
> There is no applicable method for the generic function
> #<STANDARD-GENERIC-FUNCTION PRINT-CELL-VALUE (1)>
> when called with arguments
> (CELL).
>
>
> What am I doing wrong?
>
Re-inventing the wheel?:
http://www.tilton-technology.com/cells_top.html
Please find another name for your class.
kenny
--
http://www.theoryyalgebra.com/
"We are what we pretend to be." -Kurt Vonnegut
Ken Tilton wrote:
>
>
> ···········@yahoo.co.uk wrote:
>> Lisp newbie here.
>
> Omigod, they're everywhere.
I had written a little proggy in python which prepared a set of accounts
for me. Very custom-made, and very small. I had looked at GnuCash, and
some of its reporting functions didn't really do what I wanted them to.
I looked at some of its underlying Guile stuff, and its quite long. My
custom proggy that does everything (that /I/ need it to do, anyway) is
probably about the length of one of their modules that creates one
report. So at the moment, my python program does exactly what it needs
to do, then stops.
But I figured it would be nice to have the data laid out in spreadsheet
fashion. I want the cells to have some custom-brewed properties, so
figured that using classes was the best approach. I'm working away
watching the SICP videos, and thought that I'd try my hand ("again") at
Lisp. I had in mind a little spreadsheet that works in conjunction with
ncurses. I'm just experimenting to see how I get on.
> http://www.tilton-technology.com/cells_top.html
Thanks, I'll take a look.
···········@yahoo.co.uk wrote:
> and thought that I'd try my hand ("again") at
> Lisp. I had in mind a little spreadsheet that works in conjunction with
> ncurses. I'm just experimenting to see how I get on.
Well, apropos of nothing-in-particular, I just wanted to express my
excitement at using Lisp. I've been using classes to get some
polymorphic behaviour. When I start it in SBCL, it uses ncurses as a
display, but when you start it in CLISP, for which I can't yet find an
ncurses pacakges, it uses a plain display.
I made a mistake of letting the worksheet kn ow information about the
view-controller - which mucked up the serialisation (what if you wanted
to store data from one view system, but retrieve it in another). This
meant that I had to refactor the code so that the view-controller knew
about the model, rather than the other way around.
It was pleasant to note that the transition was fairly quick and
painless. I can only imagine the amount of effort required to straighten
this all out in C.
I've never really gotten into OO in C++ - I usually end up just wishing
I had done it in vanilla C. But Lisp classes seem to just work in a way
that one would expect them to.
Can't say that I've necessarily achieved liftoff velocity for sure,
though. Lisp is a language that I occasionally dip into, then usually
slope off in disappointment again. I imagine it to be like the Wright
brothers attempt at flight - there's a lot of bumping on the ground
before one can finally become airborne.
Anyway, just my 2c.
On Sun, 02 Sep 2007 14:16:19 +0100, ···········@yahoo.co.uk wrote:
> Lisp newbie here. I'm trying to program a simple spreadsheet - it is a
> 2D array made up of cells.
>
> Here's the code I've got:
>
> (defclass cell ()
> ((value :accessor cell-value
> :initform nil
> :initarg :value)
> ))
>
> (defmethod set-cell-value ((acell cell) new-value)
> (setf (cell-value acell) new-value))
>
> (defgeneric print-cell-value (cell))
> (defmethod print-cell-value ((acell cell))
> (format t "~A " (cell-value acell)))
>
> (defparameter acell (make-instance 'cell))
> (set-cell-value acell 23)
> (print-cell-value acell)
>
>
>
> (defparameter *sheet* (make-array '(13 6) :initial-element 'cell))
Attention! Here you initialize your array with the symbol 'cell' - not
with instances of the cell class ....
> (defun num-rows (sheet)
> "Return the number of rows in a sheet"
> (car (array-dimensions sheet)))
>
> (defun num-cols (sheet)
> "Return the number of columns in a sheet"
> (cadr (array-dimensions sheet)))
>
> (defun get-row (sheet n)
> "Return the nth row (>=0) of a sheet"
> (loop for c from 0 to (1- (num-cols sheet))
> collect (aref sheet n c)))
> ;(print (get-row *sheet* 1))
>
>
> (defun print-row (sheet n)
> (let ((row (get-row sheet n)))
> (mapcar #'print-cell-value row)))
>
> (print-row *sheet* 1)
>
This will end up calling the generic function (print-cell-value 'cell) -
and that's not defined for symbols.
Try:
(defparameter *sheet* (make-array '(13 6)
:initial-element (make-instance 'cell :value 42)))
Now the array contains valid cell objects (actually, just references to
one valid cell object).
HTH Ralf Mattes
>
> The class cell will become more complicated as I add in functionality.
> At the line
> (print-cell-value acell)
> it prints 23, as expected.
>
> But when it gets to
> (print-row *sheet* 1)
> it print out
>
> debugger invoked on a SIMPLE-ERROR in thread #<THREAD "initial thread"
> {A806741}>:
> Error during processing of --eval option (LOAD #P"sheets.lisp"):
>
> There is no applicable method for the generic function
> #<STANDARD-GENERIC-FUNCTION PRINT-CELL-VALUE (1)>
> when called with arguments
> (CELL).
>
>
> What am I doing wrong?