Convert a list of symbols with value as a local variable.

following lines, will set the variables varA varB and varC, but, sorry, I do not know how to generate a list understood by 'let'

Indeed, if you want to have local variables, use let( (varA varB varC) set(varA 1) printf("Var=%d" varA)  ); ouside, let varA is now unknown (if not set elsewhere. You may write manually the list of variable you want to make local.

myList = list( list('varA 1.0) list('varB 2.0) list('varC 4.0))
foreach(mapcar a myList
set(car(a) cadr(a))
)
printf("Now defined.sum=%f\n" varA+varB)

I don't think is this is a particularly good thing to do, because it relies on run-time evaluation, but you could do:

apply('let cons(myList '(
  ; put your statements to evaluate within the quoted list
  varC=varA+varB
  println(varC)
)))

I would question why you are doing things this way, and whether there might be a better approach than building a list of variables and values and then trying to treat them as local. The beauty of SKILL and LISP is that this is easy to do, although it may not be the right thing to do...

Regards,

Andrew.

Thanks Andrew for the reply. Here's the situation to better explain why I'm doing this way.

I have external SKILL file that contains design rules, which happen to be my myList.

ex. list(list('m1space 0.02) list('m1width 0.3))

Then I have code that get/uses these rules. There shouldn't be any problem if I make it as a global variable where coder can call the rules directly but using global is too dangerous. So what I need is another function that convert my given list into a variable and are local only inside a function.

I created a function that uses association list like dRule('m1Space) but I want to improve it by just calling m1Space. 

I would probably do it like this:

 (defmacro abWithRules (ruleAssoc listOfVars @rest body)
  `(let ,(foreach mapcar varName listOfVars
          `(,varName (cadr (assoc ',varName ,ruleAssoc))))
     ,@body
     )
  )

Then I could write:

abWithRules(myList (varA varB varC)
  varC=varA+varB
  println(varC)
)

The first arg is the rule assoc list, the second is the list of local variables you want to have - which will be initialized to the corresponding values in the assoc list,  and then the rest is the body.

You can see what this expands to with:

expandMacro('abWithRules(myList (varA varB varC)
  varC=varA+varB
  println(varC)
))

which gives:

 let(((varA
            cadr(assoc('varA myList))
        )
        (varB
            cadr(assoc('varB myList))
        )
        (varC
            cadr(assoc('varC myList))
        )
    )
    (varC = (varA + varB))
    println(varC)
)

Regards,

Andrew.

Thanks Andrew. I understand the code above is close to what I need. But one problem is that I dont know how to automatically put the (varA varB varC) in abWithRules(myList (varA varB varC). I have given with myList only, and these varNames will be extracted from the given list.

Thank you.

I understand what you mean and it is very simple if I'm going to list down only the variables that I am going to use in the body of the code. However, this "let" variable declaration is hidden to the user/coder. They are writing the body of the codes only. The "let" variable declaration and the "body" written by them will be concatenated to form a complete function.

My first idea is to convert all symbols inside myList into a variable so I dont need to read and interpret the body.

Second idea is to read/interpret the body so I can list the variables that has been used. The only problem, is how to identify which one is a myList variable or another local variable.

The myList is constant list and can't be changed. But the converted symbols( to variables) can accept new values but they are local variables only and wont affect the other function.

Thank you very much.

It's working now with all your help. Thanks a lot.