[Public | Private]Sub name [(arglist)] [statements] [Exit Sub] [statements] End Sub
The Sub statement syntax has these parts:
|Public||Optional — Keyword indicating that the Sub procedure is accessible to all other procedures in all scripts.|
|Private||Optional — Keyword indicating that the Sub procedure is accessible only to other procedures in the script where it is declared.|
|name||Name of the Sub. Follows local variable naming conventions.|
|arglist||Optional — List of variables representing arguments that are passed to the Sub procedure when it is called. Multiple variables are separated by commas.|
|statements||Any group of statements to be executed within the body of the Sub procedure.|
The arglist argument has the following syntax and parts:
[ByVal | ByRef] varname[( )]
|ByVal||Indicates that the argument is passed by value.|
|ByRef||Indicates that the argument is passed by reference.|
|varname||Name of the variable representing the argument; follows standard variable naming conventions.|
The value of local variables in a Sub procedure is not preserved between calls to the procedure.
All executable code must be contained in the procedure. Nesting is not permitted; you cannot define a Sub procedure inside another Sub or Function procedure.
The Exit Sub statement causes an immediate exit from a Sub procedure. Program execution continues with the statement following the statement that called the Sub procedure. Any number of Exit Sub statements can appear anywhere in a Sub procedure.
Like a Function procedure, a Sub procedure is a separate procedure that can take arguments, perform a series of statements, and change the value of its arguments. However, unlike a Function procedure, which returns a value, a Sub procedure cannot be used in an expression.
You call a Sub procedure using the procedure name followed by the argument list. See the Call statement for specific information on how to call Sub procedures.
Variables used in Sub procedures fall into two categories: those that are explicitly declared within the procedure and those that are not. Variables that are explicitly declared in a procedure (using Dim) are always local to the procedure. Variables that are used but not explicitly declared in a procedure are also local unless they are explicitly declared at some higher level outside the procedure.
All variables in a Caché Basic Sub procedure are private. Therefore, a Sub procedure cannot access public variables, such as SQLCODE. To use public variables, use a top-level Caché Basic routine, rather than a called subroutine.
To omit an arglist argument value, you must specify an undefined variable. This is a significant difference between ObjectScript and Caché Basic. In ObjectScript an omitted argument can be specified using a placeholder comma. In Caché Basic you cannot use a placeholder comma; you must supply an undefined named variable.
Sub procedures can be recursive; that is, they can call themselves to perform a given task. However, recursion can lead to stack overflow.
A procedure can use a variable that is not explicitly declared in the procedure, but a naming conflict can occur if anything you have defined at the script level has the same name. If your procedure refers to an undeclared variable that has the same name as another procedure, constant or variable, it is assumed that your procedure is referring to that script-level name. Explicitly declare variables to avoid this kind of conflict. You can use an Option Explicit statement to force explicit declaration of variables.