Using Caché ObjectScript - InterSystems Documentation

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User-defined Code
Caché comes with many system-supplied functions (sometimes known as “intrinsic” functions), which are described in
the Caché ObjectScript Language Reference. As in other languages, ObjectScript allows you to create named code blocks
that you can invoke directly. Such blocks are known as procedures. Strictly speaking, in ObjectScript terminology, a code
block that is a procedure has a specific syntax and structure.
The syntax of a procedure definition is as follows:
ProcedureName(Parameters) [PublicVariables]
{
// code...
Quit ReturnValue
}
The elements of the procedure, here called ProcedureName, are:
• Parameters (zero or more) — These can be of any type and, as is typical of ObjectScript, you do not need to declare
their types when you define the procedure. By default, they are passed by value (not by reference). Unless otherwise
specified, their scope is local to the procedure. For more information on parameters generally, see the section “Procedure
Parameters.”
• References to public variables (zero or more) — These, too, can be of any type. The procedure can both reference and
set such a variable’s value. For more information on public variable references, see the section “Procedure Variables.”
• Declaration that the procedure is public (optional) — By default, procedures are private, which means that you can
only call them from elsewhere in the same routine (in ObjectScript terminology, a routine is a file containing one or
more procedures or other user-defined code blocks). You can also create procedures that are public, using the PUBLIC
keyword after the procedure name. Public procedures can be called from other routines or methods. For more information
on public and private procedures, see “Public and Private Procedures.”
• Code — The code in a procedure has all the features available in Caché ObjectScript. Procedure code can also include
Basic and Java. The code is delimited by curly braces and is also known as a procedure block.
• Return value (optional) — This is the value that the procedure returns, and, must be a standard ObjectScript expression.
Flow control within a procedure can specify various return values using computed expression values, multiple Quit
statements, or both.
Note:
For those familiar with versions of Caché before version 5 (and code written for those versions), procedures represent
an advance from coding that was previously available with subroutines and user-defined functions. Procedure
parameters are automatically local in scope within the procedure. They do not require a New command to ensure
that they do not overwrite other values, since they are private to the procedure and do not interact with the symbol
table. Also, the explicit declaration of public variables allows you to refer to global variables within an application,
such a bank-wide interest rate; it also allows you to create and set values for variables within the procedure that
are available to the rest of an application.
Using Caché ObjectScript 75