X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperlfaq1.pod;h=ba3d64c516bca22d146ec420a30bde22907bedd0;hb=690aedd128c9ed6a5a1b6c64bb938278029bbacb;hp=e9b1ef7184ead5546554d0aa69f8e4fa7945b03a;hpb=213329dd3d3cdcddf6cc727a9d45053e2788898b;p=p5sagit%2Fp5-mst-13.2.git diff --git a/pod/perlfaq1.pod b/pod/perlfaq1.pod index e9b1ef7..ba3d64c 100644 --- a/pod/perlfaq1.pod +++ b/pod/perlfaq1.pod @@ -1,6 +1,6 @@ =head1 NAME -perlfaq1 - General Questions About Perl ($Revision: 1.2 $, $Date: 2001/11/09 08:06:04 $) +perlfaq1 - General Questions About Perl ($Revision: 10427 $) =head1 DESCRIPTION @@ -35,8 +35,12 @@ 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/ +money. You may snoop on pending developments via the archives at +http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/ +and http://archive.develooper.com/perl5-porters@perl.org/ +or the news gateway nntp://nntp.perl.org/perl.perl5.porters or +its web interface at http://nntp.perl.org/group/perl.perl5.porters , +or read the faq at http://dev.perl.org/perl5/docs/p5p-faq.html , or you can subscribe to the mailing list by sending perl5-porters-request@perl.org a subscription request (an empty message with no subject is fine). @@ -52,55 +56,130 @@ users the informal support will more than suffice. See the answer to =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 Version 4 is old, limited, and -no longer maintained; its last patch (4.036) was in 1992, long ago and -far away.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. - -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. +(contributed by brian d foy) + +There is often a matter of opinion and taste, and there isn't any one +answer that fits anyone. In general, you want to use either the current +stable release, or the stable release immediately prior to that one. +Currently, those are perl5.10.x and perl5.8.x, respectively. + +Beyond that, you have to consider several things and decide which is best +for you. + +=over 4 + +=item * + +If things aren't broken, upgrading perl may break them (or at least issue +new warnings). + +=item * + +The latest versions of perl have more bug fixes. + +=item * + +The Perl community is geared toward supporting the most recent releases, +so you'll have an easier time finding help for those. + +=item * + +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 ). + +=item * + +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. + +=item * + +The immediate, previous releases (i.e. perl5.8.x ) are usually maintained +for a while, although not at the same level as the current releases. + +=item * + +No one is actively supporting Perl 4. Five 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. + +=item * + +There is no Perl 6 release scheduled, but it will be available when +it's ready. Stay tuned, but don't worry that you'll have to change +major versions of Perl; no one is going to take Perl 5 away from you. + +=item * + +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. perl5.10.x, where 10 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. perl5.9.x, where 9 is the minor release). + +=back + + +=head2 What are Perl 4, Perl 5, or Perl 6? + +(contributed by brian d foy) + +In short, Perl 4 is the past, Perl 5 is the present, and Perl 6 is the +future. + +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, and was released in 1994. +It can run scripts from the previous major release, Perl 4 (March 1991), +but has significant differences. It introduced the concept of references, +complex data structures, and modules. The Perl 5 interpreter was a +complete re-write of the previous perl sources. + +Perl 6 is the next major version of Perl, but it's still in development +in both its syntax and design. The work started in 2002 and is still +ongoing. Many of the most interesting features have shown up in the +latest versions of Perl 5, and some Perl 5 modules allow you to use some +Perl 6 syntax in your programs. You can learn more about Perl 6 at +http://dev.perl.org/perl6/ . See L for a history of Perl revisions. -=head2 What is perl6? +=head2 What was Ponie? -At The Second O'Reilly Open Source Software Convention, Larry Wall -announced Perl6 development would begin in earnest. Perl6 was an oft +(contributed by brian d foy) + +Ponie stands for "Perl On the New Internal Engine", started by Arthur +Bergman from Fotango in 2003, and subsequently run as a project of The +Perl Foundation. It was abandoned in 2006 +( http://www.nntp.perl.org/group/perl.ponie.dev/487 ). + +Instead of using the current Perl internals, Ponie aimed to create a +new one that would provide a translation path from Perl 5 to Perl 6 +(or anything else that targets Parrot, actually). You would have been +able to just keep using Perl 5 with Parrot, the virtual machine which +will compile and run Perl 6 bytecode. + +=head2 What is Perl 6? + +At The Second O'Reilly Open Source Software Convention, Larry Wall +announced Perl 6 development would begin in earnest. Perl 6 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. +Topaz. However, Topaz provided valuable insights to the next version +of Perl and its implementation, but was ultimately abandoned. -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. +If you want to learn more about Perl 6, or have a desire to help in +the crusade to make Perl a better place then peruse the Perl 6 developers +page at http://dev.perl.org/perl6/ and get involved. -The first alpha release is expected by Summer 2001. +Perl 6 is not scheduled for release yet, and Perl 5 will still be supported +for quite awhile after its release. Do not wait for Perl 6 to do whatever +you need to do. "We're really serious about reinventing everything that needs reinventing." --Larry Wall @@ -113,8 +192,8 @@ 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 +backward compatibility. While not quite all Perl 4 scripts run flawlessly +under Perl 5, 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). @@ -141,7 +220,7 @@ 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. +usually available for free. Don't forget Perl modules, either. They're discussed in Part 3 of this FAQ, along with CPAN, which is discussed in Part 2. @@ -155,7 +234,7 @@ 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/ +Some comparison documents can be found at http://www.perl.com/doc/FMTEYEWTK/versus/ if you really can't stop yourself. =head2 Can I do [task] in Perl? @@ -196,9 +275,7 @@ 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 +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. :-) @@ -206,13 +283,23 @@ 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. +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." + +Before the first edition of I, people commonly +referred to the language as "perl", and its name appeared that way in +the title because it referred to the interpreter. In the book, Randal +Schwartz capitalised the language's name to make it stand out better +when typeset. This convention was adopted by the community, and the +second edition became I, using the capitalized +version of the name to refer to the language. + +You may or may not choose to follow this usage. For example, +parallelism means "awk and perl" and "Python and Perl" look good, while +"awk and Perl" and "Python and perl" do not. But never write "PERL", +because perl is not an acronym, apocryphal folklore and post-facto +expansions notwithstanding. =head2 Is it a Perl program or a Perl script? @@ -233,14 +320,6 @@ tell you that a I has been compiled to physical machine code once and can then be run multiple times, whereas a I