Why does Execute return 'undefined' when accessing a loop variable?

MAXScript Frequently Asked Questions

 

The following code tries to use Execute to convert the variable var containing the string "x" to the loop variable 'x' and print its value. It returns 'undefined' 10 times instead of printing the numbers from 1 to 10.

Why does it fail?

var = "x"

for x = 1 to 10 do

(

y = execute var

print y

)

 

The answer to this question is based on the fact that Execute always uses the global scope. On the other hand, a for loop always creates a new scope and the variable 'x' is local to this scope. This is the key to understanding the original problem and its solution - the Execute just does not "see" the local variable 'x' in the global scope.

Here is a possible solution which correctly prints the numbers from 1 to 10.

global x --define a global stand-in variable for executing

var = "x" --define the string to execute

for xx = 1 to 10 do --the loop has a different var name

(

x = xx --copy the loop variable into global scope

y = execute var --execute in global scope

print y --print the result

)

 

See also

What is Scope of variables?

Frequently Asked Questions