Custom system variables

[samifox]

Hi

 

i use lots of predefined global variables that control the program flow. i wonder how autolisp reffer the variable and function with the same name?

 

(setq
			
  REBARLOWERDIA
  "3£16" ;_REBAR UPPER DIAMETER
 
)


(defun c:REBARLOWERDIA ()
 (setq	REBARLOWERDIA
 (getString (strcat "Set rebar diameter and frequncy ["
		    REBARLOWERDIA
		    "]"
	    )
 )
 )
)

 

is should be like this?

 

Thanks

Shay

[MSasu]

A good programming practice will be to use asterisks to build global variable names to easily distinguish them:

(setq [color=blue]*[/color]REBARLOWERDIA[color=blue]*[/color]
     "3£16" ;_REBAR UPPER DIAMETER
)

[samifox]

A good programming practice will be to use asterisks to build global variable names to easily distinguish them:

(setq [color=blue]*[/color]REBARLOWERDIA[color=blue]*[/color]
     "3£16" ;_REBAR UPPER DIAMETER
)

 

thanx

i wonder how autolisp reffer the variable and function with the same name?

[cwake]

i wonder how autolisp reffer the variable and function with the same name?

In a nutshell, if you try to use the same symbol name for a function and a global variable it won't work (CAVEAT - that comment is in the context of the drawing document namespace, which is what you are referring to).

The symbol will contain whatever you last set it as, eg. a string, a real, an integer, or a function. It can't be two things simultaneously.

 

 

If you are experiencing ANY confusion understanding this, perhaps you haven't realised that "C:REBARLOWERDIA" does NOT refer to the same symbol as "REBARLOWERDIA".

[BlackBox]

FWIW -

 

You may also find PRAGMA to be of interest.

 

Cheers

[samifox]

Does my code is writen correctly?

[Bhull1985]

I'm not sure your question samifox, are you asking if you did that correctly?

It appears so....

If you were trying to see if autolisp DISTINGUISHES between "C:REBARLOWERDIA" and "REBARLOWERDIA", then as clint mentioned yes it does. They are two different atoms, if I understand correctly.

[samifox]

hi

 

im writing a function (like setVar()) , for my own global variable for easily updating them as needed.

 

my problem is to access the global variables without actually call them, this the code i manage to write so far,

 

thanks

Shay

 

(defun setValue	(var val)
 (if (= (type var) 'STR)
    (set var (getstring (strcat "Enter new value for ["var"]<"'existValue">")))
   )
)

(setq
   *upperRebarTitle*	"3£12" ;_REBAR UPPER DIAMETER
) ;_ end of setq


(defun C:UPRREBARTLT ()
 (setValue "UPRREBARTLT" "3x20")
) ;_ end of defun

[MSasu]

I will write it like this:

(defun setValue( var val / tmp1 tmp2 )
(if (not val)
 (progn
  (or (setq tmp1 (eval (read var)))
      (setq tmp1 "3£12"))
  (set (read var)
       (if (/= (setq tmp2
                     (getstring (strcat "Enter new value for [" var "] <" tmp1 ">")))
               "")
        tmp2
        tmp1))
 )
 (set (read var) val)
)
(princ)
)

 

 

Call to set a value directly:

(setValue "*upperRebarTitle*" "3x20")

Call to set a value by user input :

(setValue "*upperRebarTitle*" nil)

If the variable wasn't initialized, as default value will use "3£12".

[samifox]

I will write it like this:

(defun setValue( var val / tmp1 tmp2 )
(if (not val)
 (progn
  (or (setq tmp1 (eval (read var)))
      (setq tmp1 "3£12"))
  (set (read var)
       (if (/= (setq tmp2
                     (getstring (strcat "Enter new value for [" var "] <" tmp1 ">")))
               "")
        tmp2
        tmp1))
 )
 (set (read var) val)
)
(princ)
)

 

 

Call to set a value directly:

(setValue "*upperRebarTitle*" "3x20")

Call to set a value by user input :

(setValue "*upperRebarTitle*" nil)

If the variable wasn't initialized, as default value will use "3£12".

 

hi MSasu,

 

trying to understand how this magic was done,

this is the evaluation :

 

(set (read var) val)
(set (read var) "3x20")
(set *upperRebarTitle* "3x20")

 

now if im using

 

(set var val)

 

without (read) i get error, why?

[MSasu]

Maybe this will help you understand:

(setq var1  "VAR2"
     var2  "eggs")
(print var1)                 ;a string
(print (read var1))          ;a symbol
(print (eval (read var1)))   ;value stored in above symbol

[samifox]

Maybe this will help you understand:

(setq var1  "VAR2"
     var2  "eggs")
(print var1)                 ;a string
(print (read var1))          ;a symbol
(print (eval (read var1)))   ;value stored in above symbol

 

Thanks you very much Msasu

 

you help me understand the eval much better!