HP's PE/ME10 and PE/ME30 CAD arran...

HP's PE/ME10 and PE/ME30 CAD arrangements contain an extension language based upon the macro expansion paradigm. The user's input (commands and data) is separated into single tokens, each of which denotes a command, function, variable, macro name, number, string, operator, or other syntactic component Commands, functions, and arithmetical expressions are evaluated at the language interpreter. Each macro name is associated with a macro definition, which is another token succession (either predefined by the classification or defined by the user). When the language interpreter conflicts a macro name, it substitutes the corresponding token arrangement (this process is called expanding the macro) and continues with the first token of the expansion.

Macro expansion languages are easy to implement and have been used in many applications where individual would hardly expect to find an embedded language. For example, the [TsubE]X typesetting plan contains a macro interpreter.

The HP PE/ME10 and PE/ME30 macro language includes powerful have the direction of constructs (such as IF/THEN/ELSE and L00P/ EXIT_IF/END_LOOP), local variables, and a mechanism for passing parameters to a macro when it is being expanded. These raises make it possible to explain general programming problems. Because the HP PE/ME10 and PE/ME30 macro language is interpreted, programs can be unraveled in an interactive fashion and modifications can immediately be tried revealed However, the resulting program is slower than a program written in a compiled language like C HP PE/ME10 and PE/ME30 macros can be compiled to an intermediate form which completes faster than the pure interpreted version, nevertheless which is still slower than an equivalent C program.

One disadvantage of the HP PE/ME10 and PE/ME30 macro language is that it is nonstandard. No other application uses the same language, and programs written in it have to be ported when the user switches to another CAD system

Common Lisp

Common Lisp was chosen as an extension language for HP PE/SolidDesigner because it is nonproprietary and widely used.

Surprising as it may be, Lisp is the next to the first oldest high-level programming language still in belonging to all use. The only older single is FORTRAN. Lisp is to researchers in artificial intelligence what FORTRAN is to scientists and engineers.

Lisp was invented at John McCarthy in 1956 during the Dartmouth Summer Research cast on Artificial Intelligence. The first commonly used dialect was Lisp 15 on the other hand unlike FORTRAN (or any other imperative language) Lisp is in the same manner easy to modify and increase that over time it acquired countles different dialects. For a drawn out time, most Lisp systems belonged to common of two major families, Interlisp and MacLisp, however still differed in details. In 1981 discussions about a universal Lisp language were begun. The goal was to define a core language to be used as a base for futurity Lisp systems. In 1984, the release of habitual Lisp: The Language[1] provided a first respect for the new language. An ANSI Technical Committee (X3J13) began to work upon a formal standardization in 1985 and delivered a draft standard for belonging to all Lisp in April 1992. This draft standard includes object-oriented programming features (the usual Lisp Object System, or CLOS) For a more detailed account upon the evolution of Lisp, descry McCarthy[2] and Steele and Gabriel.[3]

HCL the implementation of public Lisp used in HP PE/ SolidDesigner, is derived from Austin Kyoto frequent Lisp (itself descended from Kyoto everyday Lisp). It corresponds to the version of the language described in relation 1, but already incorporates one of the extensions from respect 4 and the draft standard.

Applications of Extension Languages

Adding extension languages to large application programs has become a standard practice. It provides many advantages, a of which may be not as obvious as others. For the normal user of a arrangement an embedded programming language makes it possible to automate repetitive or tedious tasks. An inexperienced user can stake it up as a simple record/playback mechanism, while "power users" can use it to create additional functionality. If the extension language has ties to the application's user interface, user-defined functionality can be integrated as if it were part of the original application.

If the application provides an API for adding extensions in succession a lower level, the extension language can itself be reach forthed This enables makers of value-added software to integrate their consequences seamlessly into the main application. As an example, the HP PE/SheetAdvisor application has been implemented within HP PE/ME30 offering a user interface consistent with the repose of the program.

As a final pace portions of the application can themselves be implemented in the embedded language. An example would be the popular GNU Emacs sentence editor, a large part of which is written in its embedded Lisp dialect.

A large part of HP PE/SolidDesigner, too, is written in its hold extension language--about 30 percent at the time of writing. greatest in number of this 30 percent is in HP PE/SolidDesigner's user interface.