Using Variable Scope

Scope refers to the accessibility of a function and its values. A Cicode variable can be defined as any one of three types of scope - global, module, and local. By default, Cicode variables are module scope, unless they are declared within a function.

Variables have the following format:

DataType Name [=Value];

Global Variables

A global Cicode variable can be shared across all Cicode files in the system (as well as across include projects). They cannot be accessed on pages or databases (for example, Alarm.dbf).

Global Cicode variables are prefixed with the keyword GLOBAL, and needs to be declared at the start of the Cicode file. For example:

GLOBAL STRING sDefaultPage = "Mimic";
INT
FUNCTION
MyPageDisplay(STRING sPage)
INT iStatus;
iStatus = PageDisplay(sPage);
IF iStatus <> 0 THEN
PageDisplay(sDefaultPage);
END
RETURN iStatus;
END

The variable sDefaultPage could then be used in any function of any Cicode file in the system.

Note: Use global variables sparingly if at all. If you have many such variables being used by many functions, finding bugs in your program can become time consuming. Use local variables wherever possible. Global Cicode STRING types are 256 bytes.

Module Variables

A module Cicode variable is specific to the file in which it is declared. This means that it can be used by any function in that file, but not by functions in other files.

By default, Cicode variables are defined as module, therefore prefixing is not required (though a prefix of MODULE could be added if desired). Module variables should be declared at the start of the file. For example:

STRING sDefaultPage = "Mimic";
INT
FUNCTION
MyPageDisplay(STRING sPage)
INT Status;
Status = PageDisplay(sPage);
IF Status <> 0 THEN
PageDisplay(sDefaultPage);
END
RETURN Status;
END
INT
FUNCTION
DefaultPageDisplay()
PageDisplay(sDefaultPage);
END

Note: Use module variables sparingly if at all. If you have many such variables being used by many functions, finding bugs in your program can become time-consuming. Use local variables wherever possible.

Local Variables

A local Cicode variable is only recognized by the function within which it is declared, and can only be used by that function. You need to declare local variables before you can use them.

Any variable defined within a function (that is, after the function name) is a local variable, therefore no prefix is needed. Local variables are destroyed when the function exits.

Local variables take precedence over global and module variables. If you define a local variable in a function with the same name as a global or module variable, the local variable is used; the global/module variable is unaffected by the function. This situation should be avoided, however, as it is likely to cause confusion.

Local Variables and Variable Tags

Local variables have limited functionality compared with variable tags. Limitations are:

• Qualities of Override, OverrideMode, ControlMode and Status elements are showing Bad with extended substatus QUAL_EXT_INVALID_ARGUMENT. Writing to the elements returns error Invalid argument passed (274).

• Values of Override, OverrideMode, ControlMode and Status elements are showing 0.

• Respective timestamps and quality of Field, Valid and default elements are the same.

• Field, Valid and default elements can be read.

• Field and default elements can be written.

See Also

Using Variables

Variable Scope Standards