4th Dimension (software)

History

Silver Surfer, as it was known during early development, was developed by Laurent Ribardière in 1984. Following negotiations with Ribardiere it was planned that Apple Inc. (formerly Apple Computer Inc) would publish the software but Apple canceled the plan, reportedly due to pressure from other potential database publishers who claimed that if Apple had their own 'brand' database, 3rd party products would be disadvantaged in the marketplace. Apple tried at the time to ensure well known software publishers supported the Macintosh platform and as a result, the project reverted to Laurent Ribardière, who with the French businesswoman Marylene Delbourg-Delphis published 4th Dimension. Although independently published, Apple supported the new venture and used 4D extensively throughout the organization for projects including fitness center management and CIM (Computer Integrated Manufacturing). A number of Apple personnel became 4D experts, including Lance McAndrew in Apple's Cupertino headquarters and Andrew O'Donoghue in Apple's Irish based European manufacturing headquarters, where a 4th Dimension application managed the entire European Service Center administration.

Over the next few years 4th Dimension's installed base grew and the publisher ACI, established a US-based subsidiary ACIUS, initially led by Guy Kawasaki. After 16 years of operating as ACIUS up to 2000, the name was officially changed to 4D Inc.

In 1993, 4D Server v1.1, the client/server version of 4th Dimension was introduced along with the release of 4th Dimension v3.1.

In 1995, 4D v3.5 went cross-platform and has since then supported both the Microsoft Windows and Apple Macintosh operating systems.

In 1997, 4D v6 was the first version of 4D to contain a fully integrated web server, allowing developers to translate 4D forms into HTML on the fly using only the 4D language.

In 2004, 4D 2004 was the first version of 4D to allow developers to create standalone, client/server, web and Service Oriented Applications (SOA)without changing any code.

In 2008, 4D v11 added a SQL layer to the 4D database engine and extending native SQL in to the 4D programming language which allowed 4D developers to write native SQL code to connect to either local or remote servers

In 2010, 4D v12 integrated the ability to execute PHP functions/scripts from within the 4D programming language. This version also supported new replication and synchronization commands and included a 64 bit version of 4D Server

Architecture

A 4D application can run in either Standalone mode or Client-Server mode.

Single-User

In Standalone mode, the 4D application (4D.exe on Windows or 4D.app on Mac) is used to open the structure file (4DB/4DC) file directly along with the associated data file (4DD).

Client-Server

In the Client-Server paradigm the 4D Server application (4DServer.exe on Windows or 4DServer.app on Mac) is used to open the structure file (4DB/4DC) file directly along with the associated data file (4DD). 4D may then be used in remote mode to connect to the 4D Server.

Application Editions

4D has two applications; 4D and 4D Server. 4D Server runs only as a server but 4D can be run in either standalone or remote mode.

4D

4D can be run in two modes. 4D in single-user mode allows for 1 person to run the application. 4D in remote mode is used for connecting to a 4D Server.

4D Server

4D Server is used for Client-Server connectivity to the application. In this mode, 4D Server loads the structure file (4DB or 4DC) and also the datafile (4DD) and provides network access to 4D (in remote). Each workstation has a dynamically updated cache of the resources they are working with, while the 4D Server maintains the data and code.

Syntax

This section will include syntax examples demonstrating different programming constructs used in 4D, such as for loops and variable usage.

Data Types

4D fields, variables, and expressions can be of the following data types:

More info on 4D data type can be found on the 4D Data Types documentation page

Variable Scope

Local variables are prefixed with a $ like $myLocalVariable and only live for the duration of the method.

Process variables have no prefix like myProcessVariable and live throughout the duration of the process.

Inter-process (or Global) variables are prefixed with a <> like <>myGlobalVariable and live throughout the duration of the application.

For

For(vCounter;1;100) // Do something End for

While

$i :=1 // Initialize the counter While($i<=100) // Loop 100 times // Do something $i :=$i +1 // Need to increment the counter End while

Repeat

$i :=1 // Initialize the counter Repeat // Do something $i :=$i +1 // Need to increment the counter Until($i=100) // Loop 100 times

Optimizing loops

You can use Real, Integer, and Long Integer variables as well as inter-process, process, and local variable counters. For lengthy repetitive loops, especially in compiled mode, use local Long Integer variables.

Here is an example:

C_LONGINT($vlCounter) // use local Long Integer variables For($vlCounter;1;10000) // Do something End for

Nested Loops

The following example goes through all the elements of a two-dimensional array:

For($vlElem;1;Size of array(anArray)) // ... // Do something with the row // ... For($vlSubElem;1;Size of array(anArray{$vlElem})) // Do something with the element anArray{$vlElem}{$vlSubElem}:=... End for End for

The following example builds an array of pointers to all the date fields present in the database:

ARRAY POINTER($apDateFields;0) $vlElem:=0 For($vlTable;1;Get last table number) // loop over each table number with $vTable as the number If(Is table number valid($vlTable)) // check if table number $vTable is valid // only loop on the valid table For($vlField;1;Get last field number($vlTable)) // loop over each field number within current table // with $vlField as the current field number If(Is field number valid($vlTable;$vlField)) // check if field number is valid $vpField:=Field($vlTable;$vlField) // get pointer to field If(Type($vpField->)=Is date) // check if current field is a date // only performs these actions if field is a date $vlElem:=$vlElem+1 INSERT IN ARRAY($apDateFields;$vlElem) $apDateFields{$vlElem}:=$vpField End if End If End for End If End for