destructive setq ?

[newdep]

Hi Lutz,



The problem below looks familiar to me but i cant find/recall the explenation in the manual,

perhpas you can clear me up.. I would intepret it as a bug , as its not explained as a feature in the manual.



The question is , why doesn't the use of -1 or 'last apply to setq/setf for strings?

As the impression is made inside the manual that setq/setf can be used for string manipulation.



Problem is, with common sense, im unable to append 2 strings without deleting the last char. of the first.

Code Select Expand

> (setq A "Hello/")
"Hello/"
> (setq (A -1) "world")
"world"
> A
"Helloworld"
> (setq (A -1) "!")
"!"
> A
"Helloworl!"
> (setq (last A) "!")
"!"
> A
"Helloworl!"
>


[Lutz]

It behaves exactly like it should, analogous to lists:

Code Select Expand

> (set 'A '(w o r l d))
(w o r l d)
> (setf (A -1) '!)
!
> A
(w o r l !)
>

the -1 refers to the last element, which gets replaced. To append to a string or list destructively use either  'push':

Code Select Expand


> (set 'A "world")
"world"
> (push "!" A -1)
"world!"

or 'extend':

Code Select Expand


> (set 'A "world")
"world"
> (extend A "!")
"world!"
> A
"world!"


ps: setf and setq work/are the same in newLISP, but I prefer use setf when used destructive