Scripting Guide - SAS

Chapter 8 Programming Methods 199
Advanced Scoping and Namespaces
Note: Names Default To Here(1) defines a mode for a particular script. It is not a global function.
One script can have this mode turned on, while another script can have it turned off. The default setting is
off.
In JMP 8 and earlier, the only method to the insulate scripts was to use lengthy names that were less likely to
collide with names in other scripts. Using Names Default To Here(1) makes this technique
unnecessary.
Local() creates local scopes only in specific contexts within a script and cannot enclose a longer script with
interacting functions, while Names Default To Here(1) creates a local scope for an entire script.
If you have simple scripting needs, this single command might be sufficient.
Handling Unqualified Named Variable References
The Names Default To Here() function determines how unqualified named variable references are
resolved. Explicitly scoping a variable using here:var_name always works, whether Names Default To
Here() is on or off. See “Scoped Names” on page 201 for details about here and other scopes.
Enabling the Names Default To Here mode associates a scope called Here with an executing script. The Here
scope contains all of the unqualified named variables that are created when they are the target of an
assignment (as an L-value). In JMP 8 and earlier, these variables normally would have been placed in the
Global scope. Using a Here scope keeps variables in multiple executing scripts separate from each other,
avoiding name collisions and simplifying the scripting and management of variable name collisions. You can
still share information using the Global scope.
Names Default To Here and Global Variables
Run this example script one line at a time to see how the Names Default To Here() function changes
the resolution of variable names.
Example Script
a=1;
Names Default To Here(1);
a=5;
show(global:a, a, here:a);
global:a = 1;
a = 5;
here:a = 5;
1. Run the first line to create a global variable named a that holds the value 1.
2. Run the second line to turn on the Names Default To Here mode.
3. Run the third line to create a new variable named a in the local space that holds the value 5. This line
does not change the value assigned to the global variable a.
4. Run the fourth line to see how scoped and unscoped variables are resolved.
The unqualified a is resolved to here:a. If Names Default To Here() were not on, a would be resolved
to the global variable named a.