Angel \”Java\” Lopez on Blog

January 13, 2010

AjClipper: a Clipper-like interpreter that uses .NET

Filed under: .NET, AjClipper, ASP.NET, Open Source Projects — ajlopez @ 10:57 am

You can find a Clipper-like (I wrote Remember Clipper; you’ll find more links in that post) interpreter source code at my Code Katas Google project:

It’s an interpreter, written in C#, that can create and use native .NET objects. I wrote the interpreter to:

– Practice TDD
– Create a simple tool to leverage Clipper knowledge in one of my teams, to learn more .NET concepts

I should write posts about internal implementation, access to .NET objects, manage of work areas, etc… One idea I’m exploring, is running the interpreter from an ASP.NET web page:


(There is a web app in the project containing the above test page).

My collected links about Clipper:

I should improve the access to database, and complete language command and features. Keep tuned!

Angel “Java” Lopez

July 7, 2009

Remember Clipper

Filed under: .NET, AjClipper, Programming Languages — ajlopez @ 9:28 am

These days, I’m working in a reimplementation of a full health systems, originally written in the venerable programming language Clipper. It’s a big project, with many use cases, including administration, pharmacy, stock, diets, health management.

I met DBase II at early 80s. It ran in many operating systems, as an interpreter. At late 80s, I met Clipper from Nantucket, for DOS. Some of you remember Fox, adquired by Microsoft years later.

I found some info about Clipper. Those interested in the language, can visit:

CA-Clipper 5.3 . Guide To CA-Clipper – Menu

Clipper (programming language) – Wikipedia, the free encyclopedia

Code examples at:

The Oasis Clipper Source. Over 300,000,000,000 bytes served!

Frequent asked questions about Clipper and related stuff:

Frequently Asked Questions (FAQ 2.31) about CA-Clipper and CA-Visual Objects

One of the member of the development team, commented that while Clipper was from Nantucket, it kept updated, but when it was bought by Computer Associates, it entered in a shadow, full of pitfalls, so it was surpassed by other options.

If you still have Fox, Clipper, DBase files in your disk, you can check the products from:

CodeBase Products Overview

It seems an interesting open source project, with SQL Server support, running in many plataforms, implementing a Clipper to C compiler:

Harbour Project

As language, Clipper had its quirks, as:

– The use/abuse of SET, as in SET EXACT OFF, SET EXACT ON, that modifies the behaviour of the application
– The concept of work areas
– Thinks like MEMVARS, that I still to understand)

I’m having fun, writing an interpreter, AjClipper in C#:

I have two simple programs running using my interpreter:

? "Hello World"


? "This is a test"

foo := "Hello"

bar := "World"

? foo, " ", bar

You can run them using

AjClipper.Console HelloWorld.prg SimpleTest.prg

It’s not a “killer application”, but it´s taking form. You can see my advances in my AjCodeKatas trunk:

Están escritos los tests (dando verde, por ahora):

Good Code Coverage:


I´m adding any interesting link about Clipper under

I could write an interpreter for Visual Fox dialect? I should study 🙂

Angel “Java” Lopez

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