Global variables can seem like a handy way to pass state information around in a program, but the use of global variables only works well in very
small programs. As the code base grows, you’ll need to understand every subprocedure’s impact on the global state in order to understand how the
program works. This is a task that quickly becomes impossible.
To control the situation, only the main procedure should be allowed access to global variables; it can then pass that state information to
subprocedures as parameters.
Noncompliant code example
D FirstName S 20A
D LastName S 20A
/free
FirstName = 'John';
LastName = 'Smith';
DSPLY FullName();
/end-free
P FullName B
D FullName PI 41A
/free
return FirstName + ' ' + LastName;
/end-Free
P E
Compliant solution
/free
DSPLY FullName('John':'Smith');
/end-free
P FullName B
D FullName PI 41A
D FirstName 20A Const
D LastName 20A Const
/free
return FirstName + ' ' + LastName;
/end-Free
P E
