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diff --git a/contrib/perl5/pod/perlfaq1.pod b/contrib/perl5/pod/perlfaq1.pod deleted file mode 100644 index 68c6bfd..0000000 --- a/contrib/perl5/pod/perlfaq1.pod +++ /dev/null @@ -1,328 +0,0 @@ -=head1 NAME - -perlfaq1 - General Questions About Perl ($Revision: 1.23 $, $Date: 1999/05/23 16:08:30 $) - -=head1 DESCRIPTION - -This section of the FAQ answers very general, high-level questions -about Perl. - -=head2 What is Perl? - -Perl is a high-level programming language with an eclectic heritage -written by Larry Wall and a cast of thousands. It derives from the -ubiquitous C programming language and to a lesser extent from sed, -awk, the Unix shell, and at least a dozen other tools and languages. -Perl's process, file, and text manipulation facilities make it -particularly well-suited for tasks involving quick prototyping, system -utilities, software tools, system management tasks, database access, -graphical programming, networking, and world wide web programming. -These strengths make it especially popular with system administrators -and CGI script authors, but mathematicians, geneticists, journalists, -and even managers also use Perl. Maybe you should, too. - -=head2 Who supports Perl? Who develops it? Why is it free? - -The original culture of the pre-populist Internet and the deeply-held -beliefs of Perl's author, Larry Wall, gave rise to the free and open -distribution policy of perl. Perl is supported by its users. The -core, the standard Perl library, the optional modules, and the -documentation you're reading now were all written by volunteers. See -the personal note at the end of the README file in the perl source -distribution for more details. See L<perlhist> (new as of 5.005) -for Perl's milestone releases. - -In particular, the core development team (known as the Perl Porters) -are a rag-tag band of highly altruistic individuals committed -to producing better software for free than you could hope to -purchase for money. You may snoop on pending developments via -nntp://news.perl.com/perl.porters-gw/ and the Deja archive at -http://www.deja.com/ using the perl.porters-gw newsgroup, or you can -subscribe to the mailing list by sending perl5-porters-request@perl.org -a subscription request. - -While the GNU project includes Perl in its distributions, there's no -such thing as "GNU Perl". Perl is not produced nor maintained by the -Free Software Foundation. Perl's licensing terms are also more open -than GNU software's tend to be. - -You can get commercial support of Perl if you wish, although for most -users the informal support will more than suffice. See the answer to -"Where can I buy a commercial version of perl?" for more information. - -=head2 Which version of Perl should I use? - -You should definitely use version 5. Version 4 is old, limited, and -no longer maintained; its last patch (4.036) was in 1992, long ago and -far away. Sure, it's stable, but so is anything that's dead; in fact, -perl4 had been called a dead, flea-bitten camel carcass. The most recent -production release is 5.6 (although 5.005_03 is still supported). -The most cutting-edge development release is 5.7. Further references -to the Perl language in this document refer to the production release -unless otherwise specified. There may be one or more official bug fixes -by the time you read this, and also perhaps some experimental versions -on the way to the next release. All releases prior to 5.004 were subject -to buffer overruns, a grave security issue. - -=head2 What are perl4 and perl5? - -Perl4 and perl5 are informal names for different versions of the Perl -programming language. It's easier to say "perl5" than it is to say -"the 5(.004) release of Perl", but some people have interpreted this -to mean there's a language called "perl5", which isn't the case. -Perl5 is merely the popular name for the fifth major release (October 1994), -while perl4 was the fourth major release (March 1991). There was also a -perl1 (in January 1988), a perl2 (June 1988), and a perl3 (October 1989). - -The 5.0 release is, essentially, a ground-up rewrite of the original -perl source code from releases 1 through 4. It has been modularized, -object-oriented, tweaked, trimmed, and optimized until it almost doesn't -look like the old code. However, the interface is mostly the same, and -compatibility with previous releases is very high. -See L<perltrap/"Perl4 to Perl5 Traps">. - -To avoid the "what language is perl5?" confusion, some people prefer to -simply use "perl" to refer to the latest version of perl and avoid using -"perl5" altogether. It's not really that big a deal, though. - -See L<perlhist> for a history of Perl revisions. - -=head2 What is perl6? - -At The Second O'Reilly Open Source Software Convention, Larry Wall -announced Perl6 development would begin in earnest. Perl6 was an oft -used term for Chip Salzenberg's project to rewrite Perl in C++ named -Topaz. However, Topaz should not be confused with the nisus to rewrite -Perl while keeping the lessons learned from other software, as well as -Perl5, in mind. - -If you have a desire to help in the crusade to make Perl a better place -then peruse the Perl6 developers page at http://www.perl.org/perl6/ and -get involved. - -The first alpha release is expected by Summer 2001. - -"We're really serious about reinventing everything that needs reinventing." ---Larry Wall - -=head2 How stable is Perl? - -Production releases, which incorporate bug fixes and new functionality, -are widely tested before release. Since the 5.000 release, we have -averaged only about one production release per year. - -Larry and the Perl development team occasionally make changes to the -internal core of the language, but all possible efforts are made toward -backward compatibility. While not quite all perl4 scripts run flawlessly -under perl5, an update to perl should nearly never invalidate a program -written for an earlier version of perl (barring accidental bug fixes -and the rare new keyword). - -=head2 Is Perl difficult to learn? - -No, Perl is easy to start learning--and easy to keep learning. It looks -like most programming languages you're likely to have experience -with, so if you've ever written a C program, an awk script, a shell -script, or even a BASIC program, you're already partway there. - -Most tasks only require a small subset of the Perl language. One of -the guiding mottos for Perl development is "there's more than one way -to do it" (TMTOWTDI, sometimes pronounced "tim toady"). Perl's -learning curve is therefore shallow (easy to learn) and long (there's -a whole lot you can do if you really want). - -Finally, because Perl is frequently (but not always, and certainly not by -definition) an interpreted language, you can write your programs and test -them without an intermediate compilation step, allowing you to experiment -and test/debug quickly and easily. This ease of experimentation flattens -the learning curve even more. - -Things that make Perl easier to learn: Unix experience, almost any kind -of programming experience, an understanding of regular expressions, and -the ability to understand other people's code. If there's something you -need to do, then it's probably already been done, and a working example is -usually available for free. Don't forget the new perl modules, either. -They're discussed in Part 3 of this FAQ, along with CPAN, which is -discussed in Part 2. - -=head2 How does Perl compare with other languages like Java, Python, REXX, Scheme, or Tcl? - -Favorably in some areas, unfavorably in others. Precisely which areas -are good and bad is often a personal choice, so asking this question -on Usenet runs a strong risk of starting an unproductive Holy War. - -Probably the best thing to do is try to write equivalent code to do a -set of tasks. These languages have their own newsgroups in which you -can learn about (but hopefully not argue about) them. - -Some comparison documents can be found at http://language.perl.com/versus/ -if you really can't stop yourself. - -=head2 Can I do [task] in Perl? - -Perl is flexible and extensible enough for you to use on virtually any -task, from one-line file-processing tasks to large, elaborate systems. -For many people, Perl serves as a great replacement for shell scripting. -For others, it serves as a convenient, high-level replacement for most of -what they'd program in low-level languages like C or C++. It's ultimately -up to you (and possibly your management) which tasks you'll use Perl -for and which you won't. - -If you have a library that provides an API, you can make any component -of it available as just another Perl function or variable using a Perl -extension written in C or C++ and dynamically linked into your main -perl interpreter. You can also go the other direction, and write your -main program in C or C++, and then link in some Perl code on the fly, -to create a powerful application. See L<perlembed>. - -That said, there will always be small, focused, special-purpose -languages dedicated to a specific problem domain that are simply more -convenient for certain kinds of problems. Perl tries to be all things -to all people, but nothing special to anyone. Examples of specialized -languages that come to mind include prolog and matlab. - -=head2 When shouldn't I program in Perl? - -When your manager forbids it--but do consider replacing them :-). - -Actually, one good reason is when you already have an existing -application written in another language that's all done (and done -well), or you have an application language specifically designed for a -certain task (e.g. prolog, make). - -For various reasons, Perl is probably not well-suited for real-time -embedded systems, low-level operating systems development work like -device drivers or context-switching code, complex multi-threaded -shared-memory applications, or extremely large applications. You'll -notice that perl is not itself written in Perl. - -The new, native-code compiler for Perl may eventually reduce the -limitations given in the previous statement to some degree, but understand -that Perl remains fundamentally a dynamically typed language, not -a statically typed one. You certainly won't be chastised if you don't -trust nuclear-plant or brain-surgery monitoring code to it. And Larry -will sleep easier, too--Wall Street programs not withstanding. :-) - -=head2 What's the difference between "perl" and "Perl"? - -One bit. Oh, you weren't talking ASCII? :-) Larry now uses "Perl" to -signify the language proper and "perl" the implementation of it, -i.e. the current interpreter. Hence Tom's quip that "Nothing but perl -can parse Perl." You may or may not choose to follow this usage. For -example, parallelism means "awk and perl" and "Python and Perl" look -OK, while "awk and Perl" and "Python and perl" do not. But never -write "PERL", because perl isn't really an acronym, apocryphal -folklore and post-facto expansions notwithstanding. - -=head2 Is it a Perl program or a Perl script? - -Larry doesn't really care. He says (half in jest) that "a script is -what you give the actors. A program is what you give the audience." - -Originally, a script was a canned sequence of normally interactive -commands--that is, a chat script. Something like a UUCP or PPP chat -script or an expect script fits the bill nicely, as do configuration -scripts run by a program at its start up, such F<.cshrc> or F<.ircrc>, -for example. Chat scripts were just drivers for existing programs, -not stand-alone programs in their own right. - -A computer scientist will correctly explain that all programs are -interpreted and that the only question is at what level. But if you -ask this question of someone who isn't a computer scientist, they might -tell you that a I<program> has been compiled to physical machine code -once and can then be run multiple times, whereas a I<script> must be -translated by a program each time it's used. - -Perl programs are (usually) neither strictly compiled nor strictly -interpreted. They can be compiled to a byte-code form (something of a -Perl virtual machine) or to completely different languages, like C or -assembly language. You can't tell just by looking at it whether the -source is destined for a pure interpreter, a parse-tree interpreter, -a byte-code interpreter, or a native-code compiler, so it's hard to give -a definitive answer here. - -Now that "script" and "scripting" are terms that have been seized by -unscrupulous or unknowing marketeers for their own nefarious purposes, -they have begun to take on strange and often pejorative meanings, -like "non serious" or "not real programming". Consequently, some Perl -programmers prefer to avoid them altogether. - -=head2 What is a JAPH? - -These are the "just another perl hacker" signatures that some people -sign their postings with. Randal Schwartz made these famous. About -100 of the earlier ones are available from -http://www.perl.com/CPAN/misc/japh . - -=head2 Where can I get a list of Larry Wall witticisms? - -Over a hundred quips by Larry, from postings of his or source code, -can be found at http://www.perl.com/CPAN/misc/lwall-quotes.txt.gz . - -Newer examples can be found by perusing Larry's postings: - - http://x1.dejanews.com/dnquery.xp?QRY=*&DBS=2&ST=PS&defaultOp=AND&LNG=ALL&format=terse&showsort=date&maxhits=100&subjects=&groups=&authors=larry@*wall.org&fromdate=&todate= - -=head2 How can I convince my sysadmin/supervisor/employees to use version 5/5.005/Perl instead of some other language? - -If your manager or employees are wary of unsupported software, or -software which doesn't officially ship with your operating system, you -might try to appeal to their self-interest. If programmers can be -more productive using and utilizing Perl constructs, functionality, -simplicity, and power, then the typical manager/supervisor/employee -may be persuaded. Regarding using Perl in general, it's also -sometimes helpful to point out that delivery times may be reduced -using Perl compared to other languages. - -If you have a project which has a bottleneck, especially in terms of -translation or testing, Perl almost certainly will provide a viable, -quick solution. In conjunction with any persuasion effort, you -should not fail to point out that Perl is used, quite extensively, and -with extremely reliable and valuable results, at many large computer -software and hardware companies throughout the world. In fact, -many Unix vendors now ship Perl by default. Support is usually -just a news-posting away, if you can't find the answer in the -I<comprehensive> documentation, including this FAQ. - -See http://www.perl.org/advocacy/ for more information. - -If you face reluctance to upgrading from an older version of perl, -then point out that version 4 is utterly unmaintained and unsupported -by the Perl Development Team. Another big sell for Perl5 is the large -number of modules and extensions which greatly reduce development time -for any given task. Also mention that the difference between version -4 and version 5 of Perl is like the difference between awk and C++. -(Well, OK, maybe it's not quite that distinct, but you get the idea.) -If you want support and a reasonable guarantee that what you're -developing will continue to work in the future, then you have to run -the supported version. As of April 2001 that probably means -running either of the releases 5.6.1 (released in April 2001) or -5.005_03 (released in March 1999), although 5.004_05 isn't that bad -if you B<absolutely> need such an old version (released in April 1999) -for stability reasons. Anything older than 5.004_05 shouldn't be used. - -Of particular note is the massive bug hunt for buffer overflow -problems that went into the 5.004 release. All releases prior to -that, including perl4, are considered insecure and should be upgraded -as soon as possible. - -In August 2000 in all Linux distributions a new security problem was -found in the optional 'suidperl' (not built or installed by default) -in all the Perl branches 5.6, 5.005, and 5.004, see -http://www.cpan.org/src/5.0/sperl-2000-08-05/ - -=head1 AUTHOR AND COPYRIGHT - -Copyright (c) 1997, 1998, 1999, 2000, 2001 Tom Christiansen and Nathan -Torkington. All rights reserved. - -When included as an integrated part of the Standard Distribution -of Perl or of its documentation (printed or otherwise), this works is -covered under Perl's Artistic Licence. For separate distributions of -all or part of this FAQ outside of that, see L<perlfaq>. - -Irrespective of its distribution, all code examples here are in the public -domain. You are permitted and encouraged to use this code and any -derivatives thereof in your own programs for fun or for profit as you -see fit. A simple comment in the code giving credit to the FAQ would -be courteous but is not required. |
