Scripting Guide - SAS

Chapter 8 Programming Methods 217
Advanced Programming Concepts
The use of Default Local localizes all the names that:
• Are not scoped as globals (for example, ::name)
• Are not scoped as data table column names (for example, :name)
• Occur without parentheses after them (for example, are not of the form name(...))
For example, the following function sums three numbers.
add3 = Function({a, b, c}, {temp}, temp=a+b; temp+c);
X=add3(1, 5, 9);
The following function does the same thing, automatically finding locals.
add3 = Function({a, b, c}, {Default Local}, temp=a+b; temp+c);
X=add3(1, 5, 9);
In both cases, the variable temp is not a global, or, if it is already a global, remains untouched by evaluating
the functions.
Note: If you use an expression initially as local, then use it as a global, JSL changes the context. However,
an expression used globally stays resolved globally regardless of its future use.
Recursion
Includes
The Recurse function makes a recursive call of the defining function. For example, you can make a
function to calculate factorials. A factorial is the product of a number, the number minus 1, the number
minus 2, and so on, down to 1.
myfactorial=function({a},if (a==1, 1, a*recurse(a-1)));
myfactorial(5);
120
You can define recursive calculations without using Recurse. For example, you could replace Recurse by
myfactorial, and the script would still work. However, Recurse offers these advantages:
• It avoids name conflicts when a local variable has the same name as the function.
• You can recurse even if the function itself has not been named (for example, assigned to a global variable,
such as myfactorial above).
The Include function opens a script file, parses the script in it, and executes the JSL in the specified file.
include("pathname");
For example,
include("$SAMPLE_SCRIPTS/myStartupScript.jsl");
There is an option to obtain the parsed expression from the file, rather than evaluating the file.
include("pathname",