Topic: variable name

[jsr]

Hi all

Is it possible to use value of a variable as the name of another variable. For example (setq a "st") and then use st as the name of some other variable. Note that the value "st" is determined during program execution for example it may represent name of a block.

Thanks.

[Kerry]

perhaps try

Code - Auto/Visual Lisp: [Select]

1.  
2. (setq a "st"
3.       b "mo"
4. )
5.  
6.  
7. ;;< .. >
8.  
9. (set 'a 42)
10.  
11. (set (quote b) "apples")
12.  
13.  

[irneb]

Definately! Also try looking at the read & eval functions. E.g.

Code - Auto/Visual Lisp: [Select]

1. (setq st "Some arb data here")
2. (setq a "st")
3. (read a) ; Returns a symbol st
4. (print (eval (read a))) ;Evaluates the symbol st which is read from the contents of a and thus returns "Some arb data here"
5. (print st) ;Returns the same thing "Some arb data here"
6. (set (read a) "Changed data")
7. (print (eval (read a))) ;Now it returns "Changed data"
8. (print st) ;Same again "Changed data"

So see the read as something which converts a string into a lisp expression.

And eval as the opposite of quote.

[Lee Mac]

perhaps try

Code - Auto/Visual Lisp: [Select]

1.  
2. (setq a "st"
3.       b "mo"
4. )
5.  
6.  
7. ;;< .. >
8.  
9. (set 'a 42)
10.  
11. (set (quote b) "apples")
12.  
13.  

The above is no different to:

Code - Auto/Visual Lisp: [Select]

1. (setq a "st"
2.       b "mo"
3. )
4.  
5. ;;< .. >
6.  
7. (setq a 42
8.       b "apples"
9. )

Since 'setq' is simply a convenience function, short for (set (quote <symbol>) <value>)

I believe the OP was looking to bound a value to the symbol equivalent of the string "st", e.g.:

Code - Auto/Visual Lisp: [Select]

1. _$ (setq a "st")
2. "st"
3. _$ (setq b "mo")
4. "mo"
5. _$ (set (read a) 42)
6. 42
7. _$ (set (read b) "apples")
8. "apples"
9.  
10. ;; Evaluate variables:
11. _$ a
12. "st"
13. _$ b
14. "mo"
15. _$ st
16. 42
17. _$ mo
18. "apples"

[ElpanovEvgeniy]

feature set and read very slowly ...

[Kerry]

ahhh ! I misread the question