Programming Statements

Modules with No Arguments

When you define a module with no arguments, a local symbol table is not created. All symbols (variables) are global - that is, equally accessible inside and outside the module. The symbols referenced inside the module are the same as the symbols referenced outside the module environment. This means that variables created inside the module are also global, and any operations done on variables inside a module affect the global variables as well.

The following example shows a module with no arguments:

  
    >     /* module without arguments, all symbols are global.  */ 
    >  proc iml; 
    >  a=10;                                /* A is global      */ 
    >  b=20;                                /* B is global      */ 
    >  c=30;                                /* C is global      */ 
    >  start mod1;                          /* begin module     */ 
    >     p=a+b;                            /* P is global      */ 
    >     q=b-a;                            /* Q is global      */ 
    >     c=40;                             /* C already global */ 
    >  finish;                              /* end module       */ 
  
       NOTE: Module MOD1 defined. 
  
    >  run mod1; 
    >  print a b c p q; 
  
                       A         B         C         P         Q 
                      10        20        40        30        10
 

Note that after the module is executed, the following conditions exist:

• A is still 10.
• B is still 20.
• C has been changed to 40.
• P and Q are created, added to the global symbol table, and set to 30 and 10, respectively.