The Deutsch limit is an adage

Adage

An adage is a short but memorable saying which holds some important fact of experience that is considered true by many people, or that has gained some credibility through its long use....

 about visual programming language

Visual programming language

In computing, a visual programming language is any programming language that lets users create programs by manipulating program elements graphically rather than by specifying them textually. A VPL allows programming with visual expressions, spatial arrangements of text and graphic symbols, used...

s originated by Peter Deutsch

L. Peter Deutsch

L Peter Deutsch or Peter Deutsch is the founder of Aladdin Enterprises and creator of Ghostscript, a free software PostScript and PDF interpreter....

 that states:

You can’t have more than 50 visual primitives on the screen at the same time.

The term was made up by Fred Lakin, after Peter Deutsch

L. Peter Deutsch

L Peter Deutsch or Peter Deutsch is the founder of Aladdin Enterprises and creator of Ghostscript, a free software PostScript and PDF interpreter....

 made the following comment at a talk on visual programming by Scott Kim

Scott Kim

Scott Kim is an American puzzle and computer game designer, artist, and author. He started writing an occasional "Boggler" column for Discover magazine in 1990, and became an exclusive columnist in 1999, and created hundreds of other puzzles for magazines such as Scientific American and Games, as...

 and Warren Robinett

Warren Robinett

Joseph Warren Robinett, Jr. is a designer of interactive computer graphics software, notable as the developer of the Atari 2600's Adventure — the first graphical adventure video game — and as a founder of The Learning Company, where he designed Rocky's Boots and Robot Odyssey...

: "Well, this is all fine and well, but the problem with visual programming languages is that you can’t have more than 50 visual primitives

Language primitive

In computing, language primitives are the simplest elements available in a programming language. A primitive can be defined as the smallest 'unit of processing' available to a programmer of a particular machine, or can be an atomic element of an expression in a language.-Machine level primitives:A...

 on the screen at the same time. How are you going to write an operating system?"

This limit is sometimes cited as an example of the advantage of textual over visual languages, pointing out the greater information density

Information entropy

In information theory, entropy is a measure of the uncertainty associated with a random variable. In this context, the term usually refers to the Shannon entropy, which quantifies the expected value of the information contained in a message, usually in units such as bits...

 of text.

However, criticism of the limit includes that it is not clear whether a similar limit also exist in textual programming languages;http://www.faqs.org/faqs/visual-lang/faq/ and that the limit could be overcome by applying modularity

Modularity (programming)

Modular programming is a software design technique that increases the extent to which software is composed of separate, interchangeable components called modules by breaking down program functions into modules, each of which accomplishes one function and contains everything necessary to accomplish...

to visual programming as is commonly done in textual programming.

External links

• The comp.lang.visual FAQ by David McIntyre
• Parsons and Cranshaw commentary on Deutsch Limit in "Patterns of Visual Programming"
• Baeza-Yates commentary on Visual Programming