Directives 

Formats

Where:

Description

The LOCAL directive is used to reassign variable names temporarily without affecting the original contents. In Object Oriented Programming (OOP), the LOCAL directive is similar to the PROPERTY directive but is used to declare data that is only visible to processing logic.

Format 1

Assign Local Variables

LOCAL varlist

Use this format to reassign variable names temporarily without affecting the original contents. If the variable name supplied in the LOCAL directive is in current use, PxPlus will preserve its value/contents. Once the current FOR/GOSUB stack has been cleared or the program is exited, PxPlus restores variables that were designated local to their original values. (Local variables are only active until the current stack is cleared.)

The LOCAL directive can take an assignment during declaration; however, direct assignment does not work for arrays that are declared as local.

Note:
The varlist may be specified as an IOLIST using IOL=iolist. (as of PxPlus v9.10)

The * entries in the IOLIST will be ignored for a LOCAL directive. (as of PxPlus 2018)

Example:

In this example, X is designated as local for both sub-routines (CHK_IT and LOOP); therefore, the value of X is restored to its original value "1234" after the GOSUB stack is cleared for each sub-routine. Since X$ was not designated as LOCAL in the LOOP subroutine, its value has changed from "START TEST, X=" to "LOOP" after the GOSUB stack for the LOOP has been cleared.

     X=1234,X$="START TEST, X=";
     print X$,X
     gosub CHK_IT
     print "TEST DONE"
     gosub LOOP
     print X$,X," DONE";
     stop

CHK_IT:
     local X$,X;
     X$="CHECK X:";
     print X$,X
     X=X+10
     print X$,X
     return

LOOP:
     print "START LOOP, X=",X
     X$="LOOP" ! Not designated as LOCAL
     for local X=1 to 4
          print X$,X
     next X
     return

     ->run
     start TEST,X=1234
     CHECK X: 0
     CHECK X: 10
     TEST DONE
     START LOOP, X=1234
     LOOP 1
     LOOP 2
     LOOP 3
     LOOP 4
     LOOP 1234 DONE

Variables in function definitions can be designated as LOCAL to prevent changes in program variables:

def fnXY(local X, local Y, local Z)=X+Y+Z

Format 2

Define Local Properties in Object Oriented Programming

LOCAL prop1 [OBJECT], prop2 [OBJECT]...

In Object Oriented Programming (OOP), the LOCAL directive can be used to define the properties for an object class that are not exposed to external applications. They can be accessed during the execution of program logic within the object class itself.

This format of the LOCAL directive is similar to the PROPERTY directive: variable declarations may include dimensioned arrays and object references.

LOCAL properties are typically used for:

• File handles (if the object is maintained on a file).
• Security information.
• Flags and status information used by the programming logic.

If the local variable contains an object identifier to another object, specify the keyword OBJECT after the variable name. When the object is deleted, PxPlus will use the REF( ) function against the object identifier to remove it (as long as it has no other references):

def class "Customer"
local File object

When you delete an object whose class is "Customer", then the system reduces the reference count of the object whose identifier is in "File" and, if it is no longer being referenced, deletes it as well.

See Also

DEF CLASS Define Object Class
DROP CLASS Delete Class Definition
DROP OBJECT Delete Object
FUNCTION Declare Object Method
LIKE Inherit Properties
LOAD CLASS Pre-Load Class Definition
PROGRAM Create/Assign Program File
PROPERTY Declare Object Properties
RENAME CLASS Change Name of Class
STATIC Add Local Properties at Runtime
NEW( ) Create New Object
REF( ) Control Reference Count

Format 3

Define Local Variables for User-Defined Functions

DEF FNxxxxx (LOCAL var[, LOCAL var ...] )

When defining a user function, the LOCAL keyword can be used to specify that the variables declared in the parameter list are local to the function; that is, the assignment of values from the function invocation parameter list will only affect the variables while within the function.