Scripting Guide - SAS

Chapter 5 JSL Building Blocks 79
Global and Local Variables
Table 5.3 Operators and Their Function Equivalents in Order of Precedence (Continued)
Operator Function Syntax Explanation
+= Add To a+=b
AddTo(a,b)
–= Subtract To a–=b
SubtractTo(a,b)
*= Multiply To a*=b
MultiplyTo(a,b)
/= Divide To a/=b
DivideTo(a,b)
; Glue a;b
Glue(expr, expr, ...)
Add the value of b into a.
Subtract b from a, and put back into a.
Multiply b with a, and put back into a.
Divide b into a, and put back into a.
First do a, and then do b.
Global and Local Variables
Variables are names that hold values, which you reference later in scripts. There are two types of variables:
• Global variables are shared among all scripts that you run in a JMP session.
• Local variables apply only to the script context in which you define them. They can also be local to only
a piece of a script, as with variables local to a particular function.
To limit the scope of variables, you can define them in a namespace, which is a collection of variables,
functions, and other unique names. JMP has a single global variable namespace that all scripts use by
default. When you use a name plainly, without a qualifying syntax, the name is an unscoped variable and
therefore in the global namespace.
x = 1;
Putting variables in the global namespace can cause conflicts. When two scripts have variables with the same
names, the value of the variable in the last script that you run last overwrites the variable’s value in the first
script.
To prevent this problem, we recommend that you begin each script with the following line:
Names Default To Here(1);
The Names Default To Here(1); function makes all unscoped variables in the script local to that script
and does not affect the global variable namespace. “Advanced Scoping and Namespaces” on page 198
provides more details.
You can also create a variable in a specific namespace. In the following example, the x variable is created in
the aa namespace:
aa:x = 1;