STATIC

Declare and initialize static variables and arrays

Syntax

       STATIC <identifier> [[:= <initializer>], ... ]

Arguments

<identifier> is the name of the variable or array to declare static. If the <identifier> is followed by square brackets ([ ]), it is created as an array. If the <identifier> is an array, the syntax for specifying the number of elements for each dimension can be array[<nElements>, <nElements2>, …] or array[<nElements>]

[<nElements2>]… The maximum number of elements is 4096. The maximum number of dimensions is limited only by available memory.

<initializer> is the optional assignment of a value to a new static variable. An <initializer> for a static variable consists of the inline assignment operator (:=) followed by a compile-time constant expression consisting entirely of constants and operators or a literal array. If no explicit <initializer> is specified, the variable is given an initial value of NIL. In the case of an array, each element is NIL. Array identifiers cannot be given values with an <initializer>.

Note: The macro operator (&) cannot be used in a STATIC declaration statement.

Description

The STATIC statement declares variables and arrays that have a lifetime of the entire program but are only visible within the entity that creates them. Static variables are visible only within a procedure or user-defined function if declared after a PROCEDURE or FUNCTION statement. Static variables are visible to all procedures and functions in a program (.prg) file (i.e., have filewide scope) if they are declared before the first procedure or user-defined function definition in the file. Use the /N compiler option to compile a program with filewide variable scoping.

All static variables in a program are created when the program is first invoked, and all values specified in a static <initializer> are assigned to the variable before the beginning of program execution.

Declarations of static variables within a procedure or user-defined function must occur before any executable statement including PRIVATE, PUBLIC, and PARAMETERS. If a variable of the same name is declared FIELD, LOCAL, or MEMVAR within the body of a procedure or user-defined function, a compiler error occurs and no object (.OBJ) file is generated.

The maximum number of static variables in a program is limited only by available memory.

Notes

. Inspecting static variables within the Debugger: To access static variable names within the Harbour debugger, you must compile program (.prg) files using the /B option so that static variable information is included in the object (.OBJ) file.

. Macro expressions: You may not refer to static variables within macro expressions or variables. If a static variable is referred to within a macro expression or variable, a private or public variable of the same name will be accessed instead. If no such variable exists, a runtime error will be generated.

. Memory files: Static variables cannot be SAVED to or RESTOREd from memory (.mem) files.

. Type of a static local variable: Since TYPE() uses the macro operator (&) to evaluate its argument, you cannot use TYPE() to determine the type of a local or static variable or an expression containing a local or static variable reference. The VALTYPE() function provides this facility by evaluating the function argument and returning the data type of its return value.

Examples

       .  This example declares static variables both with and without
          initializers:
          STATIC aArray1[20, 10], aArray2[20][10]
          STATIC cVar, cVar2
          STATIC cString := "my string", var
          STATIC aArray := {1, 2, 3}
       .  This example manipulates a static variable within a user-
          defined function.  In this example, a count variable increments
          itself each time the function is called:
          FUNCTION MyCounter( nNewValue )
             STATIC nCounter := 0         // Initial value assigned once
             IF nNewValue != NIL
                nCounter:= nNewValue      // New value for nCounter
             ELSE
                nCounter++                // Increment nCounter
             ENDIF
             RETURN nCounter
       .  This example demonstrates a static variable declaration that
          has filewide scope.  In this code fragment, aArray is visible to both
          procedures that follow the declaration:
          STATIC aArray := {1, 2, 3, 4}
          FUNCTION One
             ? aArray[1]                  // Result: 1
             RETURN NIL
          FUNCTION Two
             ? aArray[3]                  // Result: 3
             RETURN NIL

Seealso

FUNCTION, LOCAL, PARAMETERS, PRIVATE, PROCEDURE, PUBLIC