1. <hardware> An electrical conductor.  For distances larger
	than a breadbox, a single line may consist of two electrical
	conductors in twisted, parallel, or concentric arrangement
	used to transport one logical signal.

	By extension, a (usually physical) medium such as an {optical
	fibre} which carries a signal.

	(1995-09-29)

<software> Instructions for a computer in some programming
	language, often {machine language}.  The word "code" is often
	used to distinguish instructions from {data} (e.g. "The code
	is marked 'read-only'") whereas "{software}" is used in
	contrast with "{hardware}" and may consist of more than just
	code.

	(2000-04-08)

1. <hardware> {monitor}.

	2. <language> A vector of pointers to {activation records}.
	The Nth element points to the activation record containing
	variables declared at {lexical depth} N.  This allows faster
	access to variables from outer {scopes} than the alternative
	of linked activation records (but most variable accesses are
	either local or global or occasionally to the immediately
	enclosing scope).  Displays were used in some {ALGOL}
	implementations.

	(1996-02-22)

In {object-oriented programming} sending a message to an
	{object} (to invoke a {method}) is equivalent to calling a
	{procedure} in traditional programming languages, except that
	the actual code executed may only be selected at run time
	depending on the {class} of the object.  Thus, in response to
	the message "drawSelf", the method code invoked would be
	different if the target object were a circle or a square.

	(1995-02-16)

1. A {topic group} on {FidoNet}'s {echomail} system.

	Compare {newsgroup}.

	2. A {Unix} command that just prints its arguments.

	[{Jargon File}]

<language, tool> A {high-level} programming language, started
	by {Larry Wall} in 1987 and developed as an {open source}
	project.  It has an eclectic heritage, deriving from the
	ubiquitous {C} programming language and to a lesser extent
	from {sed}, {awk}, various {Unix} {shell} languages, {Lisp},
	and at least a dozen other tools and languages.  Originally
	developed for {Unix}, it is now available for many
	{platforms}.

	Perl's elaborate support for {regular expression} matching and
	substitution has made it the {language of choice} for tasks
	involving {string manipulation}, whether for text or binary
	data.  It is particularly popular for writing {CGI scripts}.

	The language's highly flexible syntax and concise regular
	expression operators, make densely written Perl code
	indecipherable to the uninitiated.  The syntax is, however,
	really quite simple and powerful and, once the basics have
	been mastered, a joy to write.

	Perl's only {primitive} data type is the "scalar", which can
	hold a number, a string, the undefined value, or a typed
	reference.  Perl's {aggregate} data types are {arrays}, which
	are ordered lists of {scalars} indexed by {natural numbers},
	and hashes (or "{associative arrays}") which are unordered
	lists of scalars indexed by strings.  A reference can point to
	a scalar, array, hash, {function}, or {filehandle}.  {Objects}
	are implemented as references "{blessed}" with a {class} name.
	Strings in Perl are {eight-bit clean}, including {nulls}, and
	so can contain {binary data}.

	Unlike C but like most Lisp dialects, Perl internally and
	dynamically handles all memory allocation, {garbage
	collection}, and type {coercion}.

	Perl supports {closures}, {recursive functions}, {symbols}
	with either {lexical scope} or {dynamic scope}, nested {data
	structures} of arbitrary content and complexity (as lists or
	hashes of references), and packages (which can serve as
	classes, optionally inheriting {methods} from one or more
	other classes).  There is ongoing work on {threads},
	{Unicode}, {exceptions}, and {backtracking}.  Perl program
	files can contain embedded documentation in {POD} (Plain Old
	Documentation), a simple markup language.

	The normal Perl distribution contains documentation for the
	language, as well as over a hundred modules (program
	libraries).  Hundreds more are available from The
	{Comprehensive Perl Archive Network}.  Modules are themselves
	generally written in Perl, but can be implemented as
	interfaces to code in other languages, typically compiled C.

	The free availability of modules for almost any conceivable
	task, as well as the fact that Perl offers direct access to
	almost all {system calls} and places no arbitrary limits on
	data structure size or complexity, has led some to describe
	Perl, in a parody of a famous remark about {lex}, as the
	"Swiss Army chainsaw" of programming.

	The use of Perl has grown significantly since its adoption as
	the language of choice of many {World-Wide Web} developers.
	{CGI} interfaces and libraries for Perl exist for several
	{platforms} and Perl's speed and flexibility make it well
	suited for form processing and on-the-fly {web page} creation.

	Perl programs are generally stored as {text} {source} files,
	which are compiled into {virtual machine} code at run time;
	this, in combination with its rich variety of data types and
	its common use as a glue language, makes Perl somewhat hard to
	classify as either a "{scripting language}" or an
	"{applications language}" -- see {Ousterhout's dichotomy}.
	Perl programs are usually called "Perl scripts", if only for
	historical reasons.

	Version 5 was a major rewrite and enhancement of version 4,
	released sometime before November 1993.  It added real {data
	structures} by way of "references", un-adorned {subroutine}
	calls, and {method} {inheritance}.

	The spelling "Perl" is preferred over the older "PERL" (even
	though some explain the language's name as originating in the
	acronym for "Practical Extraction and Report Language").  The
	program that interprets/compiles Perl code is called
	"perl", typically "/usr/local/bin/perl" or "/usr/bin/perl".

	Current version: 5.005_03 stable, 5.005_62 in development, as
	of 1999-12-04.

	{Home (http://www.perl.com/)}.

	{Usenet} newsgroups: {news:comp.lang.perl.announce},
	{news:comp.lang.perl.misc}.

	["Programming Perl", Larry Wall and Randal L. Schwartz,
	O'Reilly & Associates, Inc.  Sebastopol, CA.  ISBN
	0-93715-64-1].

	["Learning Perl" by Randal L. Schwartz, O'Reilly & Associates,
	Inc., Sebastopol, CA].

	[{Jargon File}]

	(1999-12-04)