Topic: Modifying Lee Mac's PolyTools "PJ" routine without success.

[jlogan02]

Edit: ...thought pattern.

Thanks for all the discussion. It helps seeing more accomplished ppl discuss varying ideas that us lesser beings might not ever see or understand.

I did question what lines 7 and 39 were doing. Totally as an assumption/guess I took it to mean if the variable exists as line 7 states, error, because it should really be as line 39 states. I certainly didn't take into account versions or platforms beyond my simple though pattern.

J. Logan 

[JohnK]

Edit: ...thought pattern.

Thanks for all the discussion. It helps seeing more accomplished ppl discuss varying ideas that us lesser beings might not ever see or understand.

I did question what lines 7 and 39 were doing. Totally as an assumption/guess I took it to mean if the variable exists as line 7 states, error, because it should really be as line 39 states. I certainly didn't take into account versions or platforms beyond my simple though pattern.

J. Logan

Those lines (36, 37, 38) in Lee's code are a slightly modified version of a wonderful generic error handler skeleton ElpanovEvgeniy posted years ago. I didn't save the link but I'll paste the text below.

Essentially, what the code below does is gather up the variables and their initial values and store them in a list. This list is then evaluated later during the error handler run (very nice, clean system by ElpanovEvgeniy).

The discussion was (in a nut-shell):
Lee introduced a feature in his version. I questioned the need for that feature.

ElpanovEvgeniy's error hander:

Code: [Select]

In the beginning of function I establish a list of the necessary environment variables,
list variable always miscellaneous:
Code:
(SETQ
  ERROR-LST-
  '("AUTOSNAP" "OSMODE" "APERTURE" "HPSPACE" "HPASSOC"
    "MIRRTEXT" "AUPREC" "LUPREC" "DIMZIN" "cecolor") 
  ERROR-LST- (mapcar '(lambda (a) (list 'setvar a (getvar a))) ERROR-LST-)
  )

Function *error*
Code:
(defun *error* (msg)
  (MAPCAR 'eval ERROR-LST-))

It is a universal *error* function *smile*

[VovKa]

The discussion was (in a nut-shell):
Lee introduced a feature in his version. I questioned the need for that feature.

Evgeniy's example contains the answer to the question
it will crash on Acad2000

[Lee Mac]

I did question what lines 7 and 39 were doing. Totally as an assumption/guess I took it to mean if the variable exists as line 7 states, error, because it should really be as line 39 states. I certainly didn't take into account versions or platforms beyond my simple though pattern.

Analysing lines 36-39:

Code - Auto/Visual Lisp: [Select]

1. (setq var '(cmdecho peditaccept)
2.       val  (mapcar 'getvar var)
3. )
4. (mapcar '(lambda ( a b c ) (if a (setvar b c))) val var '(0 1))

Here we have:

Code - Auto/Visual Lisp: [Select]

1. ;; Define a variable storing a list of symbols (this could also be strings) representing system variables
2. var '(cmdecho peditaccept)

Code - Auto/Visual Lisp: [Select]

1. ;; Retrieve the current values of those system variables (some of which may be nil if the system variable doesn't exist)
2. val  (mapcar 'getvar var)

Code - Auto/Visual Lisp: [Select]

1. ;; Here, mapcar iterates over every item in the lists 'val', 'var' and (0 1)
2. ;; Within the lambda function:
3. ;;    'a' = Current system variable value (which may be nil if the system variable doesn't exist)
4. ;;    'b' = System variable symbol
5. ;;    'c' = New system variable value
6. ;; Within the lambda function, the 'if' statement just says, if the system variable has a value (i.e. it exists), set it to this new value
7. (mapcar '(lambda ( a b c ) (if a (setvar b c))) val var '(0 1))

Those lines (36, 37, 38) in Lee's code are a slightly modified version of a wonderful generic error handler skeleton ElpanovEvgeniy posted years ago.

For the record, the code is not a modification of any existing function...

[JohnK]

Great post, Lee.

[jlogan02]

Well done Lee. If I can understand that explanation, anyone can.

Thanks.