Net.Data Administration and Programming Guide for OS/400

Variable Scope

An identifier, which is a variable or a function call, becomes visible, meaning that it can be referenced when it is declared or instantiated. The region where an identifier is visible is called its scope. The five types of scope are:

• Global

  An identifier has global scope if you can reference it anywhere within a macro file. Identifiers that have global scope are:

  • Net.Data built-in functions
  • Form data
  • URL data
  • Variables instantiated from within an HTML block

• Macro file

  An identifier has this scope if its declaration appears outside of any block. A block starts with an opening bracket ({) and ends with a percent sign and bracket (%}). (Note that DEFINE blocks are excluded from this definition and should be treated as separate DEFINE statements.) An identifier with macro file scope is visible from the point that it is declared to the end of the macro file.

• FUNCTION block or MACRO_FUNCTION block

  An identifier has function block scope if:

  • The identifier is declared in the parameter list of the function definition.

    If an identifier with the same name already exists outside the function definition, then Net.Data uses the idenfitier from the function parameter list within the function block.

  • The idenfier is instantiated in the function block and is not declared or initialized prior to the function call.

  An identifier does not have function block scope if it has been declared or initialized outside of the function and is not declared in the function parameter list. When the identifier is used inside the function block, it keeps the value it has been assigned to prior to the function call. When updated inside the function block, the identifier keeps the new value after the function call.

• REPORT block

  An identifier has report block scope if it can be referenced only from within a REPORT block (for example, table column names N1, N2, ..., Nn). Only those variables that Net.Data implicitly defines as part of its table processing can have a report block scope. Any other variables that are instantiated have function block scope.

• ROW block

  An identifier has row block scope if it can only be referenced from within a ROW block (for example, table value names V1, V2, ..., Vn). Only those variables that Net.Data implicitly defines as part of its table processing can have a row block scope. Any other variables that are instantiated have function block scope.

When an identifier is referenced, it is replaced with the value of the identifier. If a reference to a variable has no value associated with it, or if a function call does not have a return value, the reference is replaced by an empty string.