Natural Language Concepts

Natural Overview and Concepts

NATURAL is a programming language developed and marketed by Software AG.

NATURAL supports Rapid Application Development to RDBMS environments with applications that are portable, scaleable and interoperable across multiple computing platforms.

Applications developed using NATURAL are modular, which contributes to its success as a tool for Rapid Application Development. In general, each module is created, maintained and stored independently of any others.

Programs

The simplest type of module is a program. A program may be free-standing or may “call” lower level modules, such as subprograms and subroutines, that also contain executable code.

A NATURAL program can execute in either batch or on-line mode, with full access to database files.

Data definition

DEFINE DATA

.

END-DEFINE

READ Control logic

IF

PERFORM subroutine_1

END-IF

END-READ

DEFINE subroutine_1.

**   Comments

END-SUBROUTINE

END END statement

Subprograms

Common logic (i.e. logic needed by multiple modules or multiple applications) is coded in subprograms so  that it can be “called” as needed. For flexibility, parameter data can be passed directly between a subprogram and the “calling” routine. Using subprograms effectively avoids redundant code, so makes application maintenance

Subroutines

Subroutines are used to code discreet sub-functions to simplify logic and improve the readability and maintainability of the code.

There are 2 types of subroutines:

· in-line subroutines

· external subroutines

In-line subroutines

        A program or subprogram will typically contain one or more in-line subroutines.

External subroutines

       An external subroutine is the same as an in-line subroutine, except that it exists independently (in a module of type subroutine) and can be “called” from any other module.

Copycode

Copycode modules contain lines of source code that can be invoked at “compilation time” into programs, subprograms or external subroutines by means of an in-line INCLUDE statement.

Defining data

     In NATURAL there are 2 ways to define data:

· in-line data definitions

· data definition modules

     There are 3 types of data definition modules:

· local data areas (LDAs)

· parameter data areas (PDAs)

· global data areas (GDAs)

Data definition using a GDA

DEFINE DATA

GLOBAL USING INVDATA /* GDA FOR INVOICING APPLICATION

LOCAL USING INVREDEF /* LDA REDEFINING INVOICING GDA

.

END-DEFINE

For global data there is nothing equivalent to in-line definition.

Programs and external subroutines (including any in-line subroutines within them) have direct access to global data, whereas subprograms  (including any in-line subroutines within them) do not.

An application, batch or on-line, can utilize a global data area (GDA) to store common data that is needed throughout the application. Since the data is stored in memory, access is very efficient.

Report

Edit masks 

       MOVE EDITED #INVOICE-AMT (EM=ZZZZZZ9.99-)

         TO #INV-AMT

Display   DISPLAY #DEPT-NBR #DOLLARS(#DEPT-NBR)

Write

DISPLAY statements are generally used only for casual output, e.g. during debugging. For more formatted output, such as a report, WRITE statements are generally preferred.

WRITE

#DEPT-NBR

7X

#DOLLARS(#DEPT-NBR) (EM=Z,ZZZ,ZZ9.99)