Creating Temporary Fields Independent of a Master File

How to:

Define a Function
Display DEFINE Functions
Clear DEFINE Functions

Reference:

DEFINE Function Limits and Restrictions

The temporary fields you create with the DEFINE and COMPUTE commands are tied to a specific Master File, and in the case of values calculated with the COMPUTE command, to a specific request. However, you can create temporary fields that are independent of either a Master File or a request using the DEFINE FUNCTION command.

A DEFINE function is a named group of calculations that use any number of input values and produce a return value. When calling a DEFINE function, you must first define the function.

A DEFINE function can be called in most of the same situations that are valid for Information Builders-supplied functions. Data types are defined with each argument. When substituting values for these arguments, the format must match the defined format. Alphanumeric arguments shorter than the specified format are padded with blanks, while longer alphanumeric arguments are truncated.

All calculations within the function are done in double precision. Format conversions occur only across equal signs (=) in the assignments that define temporary fields.

Syntax: How to Define a Function

DEFINE FUNCTION name (argument1/format1,..., argumentn/formatn)
[tempvariablea/formata [TITLE 'line1[,line2 ...']
 [DESCRiption 'description'] = expressiona;] 
   .
   .
   .
[tempvariablex/formatx = expressionx;]  
name/format = [result_expression];
END

where:

name

Is the name of the function, up to 64 characters. This must be the last field calculated in the function, and is used to return the value of the function to the calling procedure.

argument1...argumentn

Are the argument names. They can be any names that comply with FOCUS field naming rules.

format1...formatn

Are the formats of the function arguments.

If the format of an argument is alphanumeric, the argument value must also be alphanumeric. Shorter arguments are padded on the right with blanks, and longer arguments are truncated.

If the format of an argument is numeric, the argument value must also be numeric. To prevent unexpected results, you must be consistent in your use of data types.

tempvariablea...tempvariablex

Are temporary fields. Temporary fields hold intermediate values used in the function. You can define as many temporary fields as you need.

tempformata...tempformatx

Are the formats of the temporary fields.

line1,line2 ...

Are the lines of default column title to be displayed for the virtual field unless overridden by an AS phrase.

description

Is the description to be associated with the virtual field, enclosed in single quotation marks.

expressiona...expressionx

Are the expressions that calculate the temporary field values. The expressions can use parameters, constants, and other temporary fields defined in the same function.

format

Is the format of the value the function returns.

result_expression

Is the expression that calculates the value returned by the function. The expression can use parameters, constants, and temporary fields defined in the same function.

All names defined in the body of the function are local to the function. The last field defined before the END command in the function definition must have the same name as the function, and represents the return value for the function.

Reference: DEFINE Function Limits and Restrictions

The number of functions you can define and use in a session is virtually unlimited.
A DEFINE function is cleared with the DEFINE FUNCTION CLEAR command. It is not cleared by issuing a join, or by any FOCUS command.
When an expression tries to use a cleared function, an error appears.
DEFINE functions can call other DEFINE functions, but cannot call themselves.
If you overwrite or clear a DEFINE function, a subsequent attempt to use a temporary field that refers to the function generates the following warning:
```
(FOC03665) Error loading external function '%1'
```

Example: Defining a Function

The following example creates and calls the SUBTRACT function. SUBTRACT performs a calculation with the arguments VAL1 and VAL2.

DEFINE FUNCTION SUBTRACT (VAL1/D8, VAL2/D8) 
 SUBTRACT/D8.2 = VAL1 - VAL2; 
END

TABLE FILE MOVIES 
 PRINT TITLE LISTPR IN 35 WHOLESALEPR AND
 COMPUTE PROFIT/D8.2 = SUBTRACT(LISTPR,WHOLESALEPR);
 BY CATEGORY
   WHERE CATEGORY EQ 'MYSTERY' OR 'ACTION'
END

The output is:

CATEGORY  TITLE                   LISTPR  WHOLESALEPR     PROFIT
--------  -----                   ------  -----------     ------
ACTION    JAWS                     19.95        10.99       8.96
          ROBOCOP                  19.98        11.50       8.48
          TOTAL RECALL             19.99        11.99       8.00
          TOP GUN                  14.95         9.99       4.96
          RAMBO III                19.95        10.99       8.96
MYSTERY   REAR WINDOW              19.98         9.00      10.98
          VERTIGO                  19.98         9.00      10.98
          FATAL ATTRACTION         29.98        15.99      13.99
          NORTH BY NORTHWEST       19.98         9.00      10.98
          DEAD RINGERS             25.99        15.99      10.00
          MORNING AFTER, THE       19.95         9.99       9.96
          PSYCHO                   19.98         9.00      10.98
          BIRDS, THE               19.98         9.00      10.98
          SEA OF LOVE              59.99        30.00      29.99

Procedure: How to Display DEFINE Functions

Issue the following command from the Command Console:

? FUNCTION

Example: Displaying DEFINE Functions

Issuing the command

? FUNCTION

displays information similar to the following:

FUNCTIONS	CURRENTLY	ACTIVE

NAME	FORMAT	PARAMETER	FORMAT
----------	---------	---------	-------
SUBTRACT	D8.2	VAL1	D8
		VAL2	D8

If you issue the ? FUNCTION command when no functions are defined, the following appears: