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PERLFAQ1(1)	       Perl Programmers	Reference Guide		   PERLFAQ1(1)

NAME
       perlfaq1	- General Questions About Perl

VERSION
       version 5.021011

DESCRIPTION
       This section of the FAQ answers very general, high-level	questions
       about Perl.

   What	is Perl?
       Perl is a high-level programming	language with an eclectic heritage
       written by Larry	Wall and a cast	of thousands.

       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 web programming.

       Perl derives from the ubiquitous	C programming language and to a	lesser
       extent from sed,	awk, the Unix shell, and many other tools and
       languages.

       These strengths make it especially popular with web developers and
       system administrators. Mathematicians, geneticists, journalists,
       managers	and many other people also use Perl.

   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.

       The core	development team (known	as the Perl Porters) are a group 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	the archives
       <http://www.nntp.perl.org/group/perl.perl5.porters/> or read the	faq
       <http://dev.perl.org/perl5/docs/p5p-faq.html>, or you can subscribe to
       the mailing list	by sending perl5-porters-subscribe@perl.org a
       subscription request (an	empty message with no subject is fine).

       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.

   Which version of Perl should	I use?
       (contributed by brian d foy)

       There is	often a	matter of opinion and taste, and there isn't any one
       answer that fits	everyone. In general, you want to use either the
       current stable release, or the stable release immediately prior to that
       one.  Currently,	those are perl5.18.x and perl5.16.x, respectively.

       Beyond that, you	have to	consider several things	and decide which is
       best for	you.

       o   If things aren't broken, upgrading perl may break them (or at least
	   issue new warnings).

       o   The latest versions of perl have more bug fixes.

       o   The Perl community is geared	toward supporting the most recent
	   releases, so	you'll have an easier time finding help	for those.

       o   Versions prior to perl5.004 had serious security problems with
	   buffer overflows, and in some cases have CERT advisories (for
	   instance, <http://www.cert.org/advisories/CA-1997-17.html> ).

       o   The latest versions are probably the	least deployed and widely
	   tested, so you may want to wait a few months	after their release
	   and see what	problems others	have if	you are	risk averse.

       o   The immediate, previous releases (i.e. perl5.14.x ) are usually
	   maintained for a while, although not	at the same level as the
	   current releases.

       o   No one is actively supporting Perl 4. Ten years ago it was a	dead
	   camel carcass (according to this document). Now it's	barely a
	   skeleton as its whitewashed bones have fractured or eroded.

       o   There are really two	tracks of perl development: a maintenance
	   version and an experimental version.	The maintenance	versions are
	   stable, and have an even number as the minor	release	(i.e.
	   perl5.18.x, where 18	is the minor release). The experimental
	   versions may	include	features that don't make it into the stable
	   versions, and have an odd number as the minor release (i.e.
	   perl5.19.x, where 19	is the minor release).

   What	are Perl 4, Perl 5, or Perl 6?
       In short, Perl 4	is the parent to both Perl 5 and Perl 6. Perl 5	is the
       older sibling, and though they are different languages, someone who
       knows one will spot many	similarities in	the other.

       The number after	Perl (i.e. the 5 after Perl 5) is the major release of
       the perl	interpreter as well as the version of the language. Each major
       version has significant differences that	earlier	versions cannot
       support.

       The current major release of Perl is Perl 5, first released in 1994. It
       can run scripts from the	previous major release,	Perl 4 (March 1991),
       but has significant differences.

       Perl 6 is a reinvention of Perl,	it is a	language in the	same lineage
       but not compatible. The two are complementary, not mutually exclusive.
       Perl 6 is not meant to replace Perl 5, and vice versa. See "What	is
       Perl 6?"	below to find out more.

       See perlhist for	a history of Perl revisions.

   What	is Perl	6?
       Perl 6 was originally described as the community's rewrite of Perl 5,
       however as the language evolved,	it became clear	that it	is a separate
       language, but in	the same language family as Perl 5.

       Perl 6 is not intended primarily	as a replacement for Perl 5, but as
       its own thing - and libraries exist to allow you	to call	Perl 5 code
       from Perl 6 programs and	vice versa.

       Contrary	to popular belief, Perl	6 and Perl 5 peacefully	coexist	with
       one another. Perl 6 has proven to be a fascinating source of ideas for
       those using Perl	5 (the Moose object system is a	well-known example).
       There is	overlap	in the communities, and	this overlap fosters the
       tradition of sharing and	borrowing that have been instrumental to
       Perl's success.

       If you want to learn more about Perl 6 read the Perl 6 developers page
       at <http://www.perl6.org/> and get involved.

       "We're really serious about reinventing everything that needs
       reinventing."  --Larry Wall

   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	about one production release per year.

       The Perl	development team occasionally make changes to the internal
       core of the language, but all possible efforts are made toward backward
       compatibility.

   How often are new versions of Perl released?
       Recently, the plan has been to release a	new version of Perl roughly
       every April, but	getting	the release right is more important than
       sticking	rigidly	to a calendar date, so the release date	is somewhat
       flexible.  The historical release dates can be viewed at
       <http://www.cpan.org/src/README.html>.

       Even numbered minor versions (5.14, 5.16, 5.18) are production
       versions, and odd numbered minor	versions (5.15,	5.17, 5.19) are
       development versions. Unless you	want to	try out	an experimental
       feature,	you probably never want	to install a development version of
       Perl.

       The Perl	development team are called Perl 5 Porters, and	their
       organization is described at <http://perldoc.perl.org/perlpolicy.html>.
       The organizational rules	really just boil down to one: Larry is always
       right, even when	he was wrong.

   Is Perl difficult to	learn?
       No, Perl	is easy	to start learning <http://learn.perl.org/> --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 Perl	modules, either.
       They're discussed in Part 3 of this FAQ,	along with CPAN
       <http://www.cpan.org/>, which is	discussed in Part 2.

   How does Perl compare with other languages like Java, Python, REXX, Scheme,
       or Tcl?
       Perl can	be used	for almost any coding problem, even ones which require
       integrating specialist C	code for extra speed. As with any tool it can
       be used well or badly. Perl has many strengths, and a few weaknesses,
       precisely which areas are good and bad is often a personal choice.

       When choosing a language	you should also	be influenced by the resources
       <http://www.cpan.org/>, testing culture <http://www.cpantesters.org/>
       and community <http://www.perl.org/community.html> which	surrounds it.

       For comparisons to a specific language it is often best to create a
       small project in	both languages and compare the results,	make sure to
       use all the resources <http://www.cpan.org/> of each language, as a
       language	is far more than just it's syntax.

   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 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.

   When	shouldn't I program in Perl?
       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).

       If you find that	you need to speed up a specific	part of	a Perl
       application (not	something you often need) you may want to use C, but
       you can access this from	your Perl code with perlxs.

   What's the difference between "perl"	and "Perl"?
       "Perl" is the name of the language. Only	the "P"	is capitalized.	 The
       name of the interpreter (the program which runs the Perl	script)	is
       "perl" with a lowercase "p".

       You may or may not choose to follow this	usage. But never write "PERL",
       because perl is not an acronym.

   What	is a JAPH?
       (contributed by brian d foy)

       JAPH stands for "Just another Perl hacker,", which Randal Schwartz used
       to sign email and usenet	messages starting in the late 1980s. He
       previously used the phrase with many subjects ("Just another x
       hacker,"), so to	distinguish his	JAPH, he started to write them as Perl
       programs:

	   print "Just another Perl hacker,";

       Other people picked up on this and started to write clever or
       obfuscated programs to produce the same output, spinning	things quickly
       out of control while still providing hours of amusement for their
       creators	and readers.

       CPAN has	several	JAPH programs at <http://www.cpan.org/misc/japh>.

   How can I convince others to	use Perl?
       (contributed by brian d foy)

       Appeal to their self interest! If Perl is new (and thus scary) to them,
       find something that Perl	can do to solve	one of their problems. That
       might mean that Perl either saves them something	(time, headaches,
       money) or gives them something (flexibility, power, testability).

       In general, the benefit of a language is	closely	related	to the skill
       of the people using that	language. If you or your team can be faster,
       better, and stronger through Perl, you'll deliver more value. Remember,
       people often respond better to what they	get out	of it. If you run into
       resistance, figure out what those people	get out	of the other choice
       and how Perl might satisfy that requirement.

       You don't have to worry about finding or	paying for Perl; it's freely
       available and several popular operating systems come with Perl.
       Community support in places such	as Perlmonks (
       <http://www.perlmonks.com> ) and	the various Perl mailing lists (
       <http://lists.perl.org> ) means that you	can usually get	quick answers
       to your problems.

       Finally,	keep in	mind that Perl might not be the	right tool for every
       job. You're a much better advocate if your claims are reasonable	and
       grounded	in reality. Dogmatically advocating anything tends to make
       people discount your message. Be	honest about possible disadvantages to
       your choice of Perl since any choice has	trade-offs.

       You might find these links useful:

       o   <http://www.perl.org/about.html>

       o   <http://perltraining.com.au/whyperl.html>

AUTHOR AND COPYRIGHT
       Copyright (c) 1997-2010 Tom Christiansen, Nathan	Torkington, and	other
       authors as noted. All rights reserved.

       This documentation is free; you can redistribute	it and/or modify it
       under the same terms as Perl itself.

       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.

perl v5.26.0			  2017-04-19			   PERLFAQ1(1)

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