White Paper: Dynamic Objects Overview

The Allegro family of development tools from Franz Inc. is based on "Dynamic Objects" (dynamic object-oriented programming) technology via CLOS (the Common Lisp Object System), the most advanced, non-proprietary Dynamic Objects language available today. The following provides some background information on Dynamic Objects technology and CLOS.

The Trend Towards Dynamic Object-Oriented Programming

Object-oriented programming has become the undisputed successor to the structured programming methodologies of the 70's and 80's. Modular software design, code reusability and rapid application development are just some of the many advantages of OO technology that have changed the landscape of software development.

Static OO languages such as C++ have been largely responsible for the rapid growth of OO technology. However, because these languages are not interactive, dynamic OO languages are fast becoming the development tools of choice in many new application areas.

What is Dynamic Object-Oriented Programming?

Dynamic object-oriented programming is a software development technology that enables applications to be tailored during development and at runtime, without access to source code. New objects, new classes and new behavior can be added on the fly.

Dynamic Objects is the enabling technology for user-evolved software. Developers can incrementally test working prototypes with users, resulting in significantly more usable applications. With Dynamic Objects, users can also modify an application's behavior after deployment. Intelligent agents reconfigure software applications by applying new code while the application is running.

As software applications become more intelligent and network-aware, software engineers are turning to Dynamic Objects languages because they are better suited for managing complexity.

Dynamic Objects Languages

The two most prominent Dynamic Objects languages are Smalltalk and CLOS (the Common Lisp Object System). Smalltalk, a "first generation" dynamic object-oriented language, has some limitations. Every piece of data is required to be an object, which compromises computational performance. Smalltalk supports only single inheritance, which limits the design of objects that could be easily built by inheriting. These shortcomings inspired Xerox Parc and other organizations to further explore Dynamic Objects languages. This research led to the development of CLOS, the Common Lisp Object System.

What is CLOS?

CLOS is a commercially proven, non-proprietary dynamic object-oriented language used in many major development projects worldwide. Companies such as Price Waterhouse and AT&T are using CLOS to develop sophisticated applications for financial auditing and telephone switching. General Electric and Pratt & Whitney are designing jet engines with CLOS. Boeing is designing new aircraft. Ford and Jaguar are designing new automobile systems. Motorola and Texas Instruments are using CLOS for manufacturing scheduling and integrated circuit design. And the list goes on.

CLOS Dynamic Objects Technology

CLOS is a leading-edge dynamic object-oriented (Dynamic Objects) programming environment. It is "the only language that meets all of the Gartner Groups 'must-have' and 'should-have' criteria for object-oriented languages" (ATA Research Note, 07/24/95) and is the only object-oriented language to be standardized by the American National Standards Institute (ANSI).

CLOS is a "second generation" dynamic object-oriented language. Limitations in first generation dynamic OO languages such as Smalltalk have been eliminated. For example, CLOS supports multiple inheritance, metaobject protocol, and a choice of dynamic or static typing.

CLOS is ideally suited to large, complex, mission-critical applications development with an emphasis on "user-evolved" development. CLOS enables programmers to build adaptive applications that reflect changing user needs, both throughout the development process and after deployment.

The Allegro Product Line

Franz Inc. is the world's leading supplier of dynamic object-oriented development systems based on CLOS, the ANSI standard OO language. The company's Allegro line of CLOS-based products are top-sellers in such areas as mechanical and electrical CAD, operating systems, process control, knowledge representation, document management, and robotics. Other applications built using Allegro CL include dynamic web servers which can deliver custom-tailored html pages on demand and complex telephone switches that can be dynamically upgraded to offer new telephony services without incurring downtime.

For more information on Allegro CL, please see the Products section on our website!

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