Please help with nested COND functions

[Anonymous]

Hi All,

Please help me with the following nested "cond" function in AutoLisp.
I would like to be able to set various variables based on conditions within
conditions.

Please review the following lines and tell me what I am doing wrong.

(defun ITEMWIDTH2()
(cond
((= xitmq 2)
(and (setq itmha itm2ah itmhb itm2bh itmhc itm2ch)
(setq itmde itm1ew)(setq itmwe itm2ew)
(cond((= drbhs2 1)(setq drhs 1))((= drbhs2
2)(setq drhs 2)))
(cond((= drwhs2 1)(setq drhs 1))((= drwhs2
2)(setq drhs 2)))
);and
);cond

((= xitmq 3)
(and (setq itmha itm3ah itmhb itm3bh itmhc itm3ch)
(setq itmde (+ itm1ew itm2ew))(setq itmwe itm3ew)
(cond((= drbhs3 1)(setq drhs 1))((= drbhs3
2)(setq drhs 2)))
(cond((= drwhs3 1)(setq drhs 1))((= drwhs3
2)(setq drhs 2)))
);and
)
);cond

);defun

Thank you in advance,
Al

[Anonymous]

Hi All,

Please review the following and tell me why it is not working:

I am trying to create a conditional function within a conditional function.

(defun ITEMWIDTH2()
(cond
((= xitmq 2)
(and (setq itmha itm2ah itmhb itm2bh itmhc itm2ch)
(setq itmde itm1ew)(setq itmwe itm2ew)
(cond((= drbhs2 1)(setq drhs 1))((= drbhs2
2)(setq drhs 2)))
(cond((= drwhs2 1)(setq drhs 1))((= drwhs2
2)(setq drhs 2)))
);and
)

((= xitmq 3)
(and (setq itmha itm3ah itmhb itm3bh itmhc itm3ch)
(setq itmde (+ itm1ew itm2ew))(setq itmwe itm3ew)
(cond((= drbhs3 1)(setq drhs 1))((= drbhs3
2)(setq drhs 2)))
(cond((= drwhs3 1)(setq drhs 1))((= drwhs3
2)(setq drhs 2)))
);and
)
);cond

);defun

Thank you,
Al

[charmingladyfool]

COND is an unusual function which may take any arbitrary number of arguments. Each argument is called a clause, and consists of a list of exactly two S-expressions. We will call the first S-expression in a clause a condition, and the second S-expression a result. Thus, a call to COND looks like this:

(COND

(condition1 result1 )

(condition2 result2 )

. . .

(T    resultN ) )

The value returned by COND is computed as follows: if condition1 is true (not NIL), then return result1; else if condition2 is true then return result2; else if ...; else return resultN. In most LISP systems, it is an error if none of the conditions are true, and the result of the COND is undefined. For this reason, T is usually used as the final condition.

___________________________________________________________________________________________________________________

Copyright © 1995, 2000 by David Matuszek
All rights reserved.
Last updated October 27, 2000

[Kent1Cooper]

I do wonder whether johnal is still waiting for a reply after more than 12 years, but anyway....

I don't think there's anything about their code that shouldn't work, and the first question I would have asked [but that was before I became a user of these Forums] would have been, "What about it doesn't work?  Does it do nothing?  Something, but not what you expect?  Is there any error message?"  Maybe some variable or other doesn't have a value set in it, or is spelled wrong, or something.  It is constructed a little oddly, though, in connection with which I would dispute what charmingladyfool posted from David Matuszek.  There can be more than one result expression evaluated/performed when a given condition returns a non-nil result, that is, the "exactly two" is incorrect:

(condition1 result1a result1b result1c ...)

(condition2 result2a result2b result2c ...)

....

The mis-belief that there must be only one result for each condition may be a confusion of the way (cond) works with the way (if) works.  In (if), the 'then' expression and the 'else' expression must each be a single item, and if more than one thing needs to be done, they must be wrapped into a single item using something such as (progn), though I guess (and) could be used to accomplish the same.  I suspect that's the reason for the (and) functions in johnal's code, but they are not needed.