Visual FoxPro

Visual FoxPro is a data-centric object-oriented and procedural programming language produced by Microsoft. It is derived from FoxPro (originally known as FoxBASE) which was developed by Fox Software beginning in 1984. Fox Technologies merged with Microsoft in 1992, after which the software acquired further features and the prefix "Visual". The last version of FoxPro (2.6) worked under Mac OS, DOS, Windows, and Unix: Visual FoxPro 3.0, the first "Visual" version, reduced platform support to only Mac and Windows, and later versions were Windows-only. The current version of Visual FoxPro is COM-based and Microsoft has stated that they do not intend to create a Microsoft .NET version.

FoxPro originated as a member of the class of languages commonly referred to as "xBase" languages, which have syntax based on the dBase programming language. Other members of the xBase language family include Clipper and Recital. (A history of the early years of xBase can be found in the dBase article.)

Visual FoxPro, commonly abbreviated as VFP, is tightly integrated with its own relational database engine, which extends FoxPro's xBase capabilities to support SQL query and data manipulation. Unlike most database management systems, Visual FoxPro is a full-featured, dynamic programming language that does not require the use of an additional general-purpose programming environment. It can be used to write not just traditional "fat client" applications, but also middleware and web applications.

Recent history

In late 2002, it was demonstrated that Visual FoxPro can run on Linux under the Wine Windows compatibility suite. In 2003, this led to complaints by Microsoft: it was claimed that the deployment of runtime FoxPro code on non-Windows machines violates the End User License Agreement.^[1]

Visual FoxPro had a rapid rise and fall in popularity as measured by the TIOBE Programming Community Index^[2]. In December 2005, VFP broke into the top 20 for the first time. In June 2006 it peaked at position 12, making it (at the time) a "B" language. By September of 2010, FoxPro and its variants had fallen out of the top 50, where it has remained ever since.

In March 2007, Microsoft announced that there will be no VFP 10^[3], thus making VFP9 (released to manufacturing on December 17, 2004) the last commercial VFP release from Microsoft. The support of Version 9 is ongoing with service packs that were released December 8, 2005 and October 11, 2007.

At the time of the end of life announcement, work on the next release codenamed Sedna (named after a recently discovered dwarf planet) which was built on top of the VFP9 codebase had already begun. "Sedna" is a set of add-ons to VFP 9.0 of xBase components to support a number of interoperability scenarios with various Microsoft technologies including SQL Server 2005, .NET Framework, Windows Vista, Office 2007, Windows Search and Team Foundation Server (TFS). Microsoft released Sedna under the Shared source license on the CodePlex site. Microsoft has clarified that the VFP core will still remain closed source. Sedna was released on January 25, 2008^[4]. As of March 2008, all xBase components of the VFP 9 SP2 (including Sedna) were available for community-development on CodePlex.

In late March 2007 a grassroots campaign was started by the Spanish-speaking FoxPro community at MasFoxPro^[5] ("MoreFoxPro" in English) to sign a petition to Microsoft to continue updating Visual FoxPro or release it to the community as Open Source. On April 3, 2007 the movement was noted by the technical press^[6]

Also on April 3, 2007 Microsoft responded to the petitioner's requests with this statement from Alan Griver:

"We're very aware of the FoxPro community and that played a large part in what we announced on March 13th. It's never an easy decision to announce that we're not going to release another version of a product and it's one that we consider very carefully.

"We're not announcing the end of FoxPro: Obviously, FoxPro applications will continue to work. By some of our internal estimates, there are more applications running in FoxPro 2.6 than there are in VFP and FoxPro 2.6 hasn't been supported in many years. Visual FoxPro 9 will be supported by Microsoft through 2015.

"For Microsoft to continue to evolve the FoxPro base, we would need to look at creating a 64-bit development environment and that would involve an almost complete rewrite of the core product. We've also invested in creating a scalable database with SQL Server, including the freely available SQL Server Express Edition. As far as forming a partnership with a third-party is concerned, we've heard from a number of large FoxPro customers that this would make it impossible for them to continue to use FoxPro since it would no longer be from an approved vendor. We felt that putting the environment into open source on CodePlex, which balances the needs of both the community and the large customers, was the best path forward."

Version information

Operating system compatibility

Information on executable files

Code samples

The FoxPro language contains commands quite similar to other programming languages such as Basic. Loops include do, if, while, for, else commands in a usage easily understood by anyone familiar with other programming languages. Commands take the form of "command" and "endcommand"

Some basic syntax samples:

FOR i = 1 to 10
   x = x + 6.5
ENDFOR
 
IF i = 25
   i = i + 1
ELSE
   i = i + 3
ENDIF
 
x = 1
DO WHILE x < 50
   x =  x + 1
ENDDO

The language also has extensive database manipulation and indexing commands. The "help" index of commands in VFP 9 has several hundred commands and functions described. The examples below show how to code the creation and indexing of tables, however VFP has table and database builder screens which create the tables and indexes without making you write code.

Hello World example:

MESSAGEBOX("Hello World")

Object

loForm = CREATEOBJECT("HiForm")
loForm.Show(1)
 
DEFINE CLASS HiForm AS Form
  AutoCenter = .T.
  Caption = "Hello, World"
 
  ADD OBJECT lblHi as Label WITH ;
    Caption = "Hello, World!"
ENDDEFINE

loMine = CREATEOBJECT("MyClass")
? loMine.cProp1   && This will work. (Double-ampersand marks an end-of-line comment)
? loMine.cProp2   && Program Error: Property CPROP2 is not found.
 
? loMine.MyMethod1()  && This will work.
? loMine.MyMethod2()  && Program Error: Property MYMETHOD2 is not found.
 
DEFINE CLASS MyClass AS Custom
  cProp1 = "My Property"    && This is a public property
  HIDDEN cProp2     && This is a private (hidden) property
 
  PROCEDURE Init()    && Class constructor
    This.cProp2 = "This is a hidden property."
  ENDPROC
 
  PROCEDURE MyMethod1()
    * This is a public method, calling a hidden method that returns
    * the value of a hidden property.
    RETURN This.MyMethod2()
  ENDPROC
 
  HIDDEN PROCEDURE MyMethod2()  && This is a private (hidden) method
    RETURN This.cProp2
  ENDPROC
ENDDEFINE

Data handling

&& Create a table
CREATE TABLE randData (iData I)
 
&& Populate with random data using xBase and SQL DML commands
FOR i = 1 TO 50
    APPEND BLANK
    REPLACE iData WITH (RAND() * 100)
 
    INSERT INTO randData (iData) VALUES (RAND() * 100)
ENDFOR
 
&& Place a structural index on the data
INDEX ON iData TAG iData
CLOSE ALL
 
&& Display ordered data using xBase-style commands
USE randData
SET ORDER TO iData
GO TOP
LIST NEXT 10  && First 10 
GO BOTTOM
SKIP -10
LIST REST     && Last 10
CLOSE ALL
 
&& Browse ordered data using SQL DML commands
SELECT * ;
  FROM randData ;
  ORDER BY iData DESCENDING

ODBC access using SQL passthrough

&& Connect to an ODBC data source
LOCAL nHnd
nHnd = SQLCONNECT ("ODBCDSN", "user", "pwd")
 
&& Execute a SQL command
LOCAL nResult
nResult = SQLEXEC (nHnd, "USE master")
IF nResult < 0
  MESSAGEBOX ("MASTER database does not exist!")
  RETURN
ENDIF
 
&& Retrieve data from the remote server and stores it in
&& a local data cursor
nResult = SQLEXEC (nHnd, "SELECT * FROM authors", "QAUTHORS")
 
&& Update a record in a remote table using parameters
PRIVATE cAuthorID, cAuthorName
cAuthorID = "1001"
cAuthorName = "New name"
nResult = SQLEXEC (nHnd, "UPDATE authors SET auth_name = ?cAuthorName WHERE auth_id = ?cAuthorID")
 
&& Close the connection
SQLDISCONNECT(nHnd)

Beta code names

• VFP 3 - Taz
• VFP 5 - RoadRunner
• VFP 6 - Tahoe
• VFP 7 - Sedona
• VFP 8 - Toledo
• VFP 9 - Europa
• VFP Next - Sedna

References

External links

Microsoft pages

• Main Visual FoxPro Microsoft page
• MSDN FoxPro support board
• VFP's online help
• Microsoft VFP 9 support
• Visual FoxPro Downloads page

Other pages

• Visual FoxPro Wiki A repository of FoxPro information (written in VFP)
• A site devoted to the history of FoxPro
• VFPx A Visual FoxPro Community effort to create open source add-ons for VFP 9.0
• www.visualfoxpro.com An initiative to help Visual FoxPro developers learn Servoy