资料来源 : Free On-Line Dictionary of Computing

Perl
     
         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)