From: Tom Christiansen Date: Thu, 7 Jan 1999 23:05:02 +0000 (-0700) Subject: FAQ jumbo patch from tchrist. X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=65acb1b1d672587d3a0d073613a475584830e38e;p=p5sagit%2Fp5-mst-13.2.git FAQ jumbo patch from tchrist. Message-Id: <199901080605.XAA20229@jhereg.perl.com> To: pumpkings@jhereg.perl.com Subject: newest version of perlfaq.pod Date: Thu, 7 Jan 1999 23:05:02 -0700 Message-Id: <199901080605.XAA20231@jhereg.perl.com> From: Tom Christiansen To: pumpkings@jhereg.perl.com Subject: newest version of perlfaq1.pod Date: Thu, 7 Jan 1999 23:05:02 -0700 Message-Id: <199901080605.XAA20233@jhereg.perl.com> From: Tom Christiansen To: pumpkings@jhereg.perl.com Subject: newest version of perlfaq2.pod Date: Thu, 7 Jan 1999 23:05:02 -0700 Message-Id: <199901080605.XAA20235@jhereg.perl.com> From: Tom Christiansen To: pumpkings@jhereg.perl.com Subject: newest version of perlfaq3.pod Date: Thu, 7 Jan 1999 23:05:02 -0700 Message-Id: <199901080605.XAA20237@jhereg.perl.com> From: Tom Christiansen To: pumpkings@jhereg.perl.com Subject: newest version of perlfaq4.pod Date: Thu, 7 Jan 1999 23:05:02 -0700 Message-Id: <199901080605.XAA20239@jhereg.perl.com> From: Tom Christiansen To: pumpkings@jhereg.perl.com Subject: newest version of perlfaq5.pod Date: Thu, 7 Jan 1999 23:05:02 -0700 Message-Id: <199901080605.XAA20241@jhereg.perl.com> From: Tom Christiansen To: pumpkings@jhereg.perl.com Subject: newest version of perlfaq6.pod Date: Thu, 7 Jan 1999 23:05:02 -0700 Message-Id: <199901080605.XAA20243@jhereg.perl.com> From: Tom Christiansen To: pumpkings@jhereg.perl.com Subject: newest version of perlfaq7.pod Date: Thu, 7 Jan 1999 23:05:03 -0700 Message-Id: <199901080605.XAA20245@jhereg.perl.com> From: Tom Christiansen To: pumpkings@jhereg.perl.com Subject: newest version of perlfaq8.pod Date: Thu, 7 Jan 1999 23:05:03 -0700 Message-Id: <199901080605.XAA20257@jhereg.perl.com> From: Tom Christiansen To: pumpkings@jhereg.perl.com Subject: newest version of perlfaq9.pod Date: Thu, 7 Jan 1999 23:05:03 -0700 p4raw-id: //depot/cfgperl@2588 --- diff --git a/pod/perlfaq.pod b/pod/perlfaq.pod index e6be112..cb35493 100644 --- a/pod/perlfaq.pod +++ b/pod/perlfaq.pod @@ -1,6 +1,6 @@ =head1 NAME -perlfaq - frequently asked questions about Perl ($Date: 1998/08/05 12:09:32 $) +perlfaq - frequently asked questions about Perl ($Date: 1999/01/08 05:54:52 $) =head1 DESCRIPTION @@ -16,42 +16,682 @@ This document. Very general, high-level information about Perl. +=over 4 + +=item * What is Perl? + +=item * Who supports Perl? Who develops it? Why is it free? + +=item * Which version of Perl should I use? + +=item * What are perl4 and perl5? + +=item * What is perl6? + +=item * How stable is Perl? + +=item * Is Perl difficult to learn? + +=item * How does Perl compare with other languages like Java, Python, REXX, Scheme, or Tcl? + +=item * Can I do [task] in Perl? + +=item * When shouldn't I program in Perl? + +=item * What's the difference between "perl" and "Perl"? + +=item * Is it a Perl program or a Perl script? + +=item * What is a JAPH? + +=item * Where can I get a list of Larry Wall witticisms? + +=item * How can I convince my sysadmin/supervisor/employees to use version (5/5.005/Perl instead of some other language)? + +=back + + =item L: Obtaining and Learning about Perl Where to find source and documentation to Perl, support, and related matters. +=over 4 + +=item * What machines support Perl? Where do I get it? + +=item * How can I get a binary version of Perl? + +=item * I don't have a C compiler on my system. How can I compile perl? + +=item * I copied the Perl binary from one machine to another, but scripts don't work. + +=item * I grabbed the sources and tried to compile but gdbm/dynamic loading/malloc/linking/... failed. How do I make it work? + +=item * What modules and extensions are available for Perl? What is CPAN? What does CPAN/src/... mean? + +=item * Is there an ISO or ANSI certified version of Perl? + +=item * Where can I get information on Perl? + +=item * What are the Perl newsgroups on USENET? Where do I post questions? + +=item * Where should I post source code? + +=item * Perl Books + +=item * Perl in Magazines + +=item * Perl on the Net: FTP and WWW Access + +=item * What mailing lists are there for perl? + +=item * Archives of comp.lang.perl.misc + +=item * Where can I buy a commercial version of Perl? + +=item * Where do I send bug reports? + +=item * What is perl.com? + +=back + + =item L: Programming Tools Programmer tools and programming support. +=over 4 + +=item * How do I do (anything)? + +=item * How can I use Perl interactively? + +=item * Is there a Perl shell? + +=item * How do I debug my Perl programs? + +=item * How do I profile my Perl programs? + +=item * How do I cross-reference my Perl programs? + +=item * Is there a pretty-printer (formatter) for Perl? + +=item * Is there a ctags for Perl? + +=item * Is there an IDE or Windows Perl Editor? + +=item * Where can I get Perl macros for vi? + +=item * Where can I get perl-mode for emacs? + +=item * How can I use curses with Perl? + +=item * How can I use X or Tk with Perl? + +=item * How can I generate simple menus without using CGI or Tk? + +=item * What is undump? + +=item * How can I make my Perl program run faster? + +=item * How can I make my Perl program take less memory? + +=item * Is it unsafe to return a pointer to local data? + +=item * How can I free an array or hash so my program shrinks? + +=item * How can I make my CGI script more efficient? + +=item * How can I hide the source for my Perl program? + +=item * How can I compile my Perl program into byte code or C? + +=item * How can I compile Perl into Java? + +=item * How can I get C<#!perl> to work on [MS-DOS,NT,...]? + +=item * Can I write useful perl programs on the command line? + +=item * Why don't perl one-liners work on my DOS/Mac/VMS system? + +=item * Where can I learn about CGI or Web programming in Perl? + +=item * Where can I learn about object-oriented Perl programming? + +=item * Where can I learn about linking C with Perl? [h2xs, xsubpp] + +=item * I've read perlembed, perlguts, etc., but I can't embed perl in +my C program, what am I doing wrong? + +=item * When I tried to run my script, I got this message. What does it +mean? + +=item * What's MakeMaker? + +=back + + =item L: Data Manipulation Manipulating numbers, dates, strings, arrays, hashes, and miscellaneous data issues. +=over 4 + +=item * Why am I getting long decimals (eg, 19.9499999999999) instead of the numbers I should be getting (eg, 19.95)? + +=item * Why isn't my octal data interpreted correctly? + +=item * Does Perl have a round() function? What about ceil() and floor()? Trig functions? + +=item * How do I convert bits into ints? + +=item * Why doesn't & work the way I want it to? + +=item * How do I multiply matrices? + +=item * How do I perform an operation on a series of integers? + +=item * How can I output Roman numerals? + +=item * Why aren't my random numbers random? + +=item * How do I find the week-of-the-year/day-of-the-year? + +=item * How can I compare two dates and find the difference? + +=item * How can I take a string and turn it into epoch seconds? + +=item * How can I find the Julian Day? + +=item * How do I find yesterday's date? + +=item * Does Perl have a year 2000 problem? Is Perl Y2K compliant? + +=item * How do I validate input? + +=item * How do I unescape a string? + +=item * How do I remove consecutive pairs of characters? + +=item * How do I expand function calls in a string? + +=item * How do I find matching/nesting anything? + +=item * How do I reverse a string? + +=item * How do I expand tabs in a string? + +=item * How do I reformat a paragraph? + +=item * How can I access/change the first N letters of a string? + +=item * How do I change the Nth occurrence of something? + +=item * How can I count the number of occurrences of a substring within a string? + +=item * How do I capitalize all the words on one line? + +=item * How can I split a [character] delimited string except when inside +[character]? (Comma-separated files) + +=item * How do I strip blank space from the beginning/end of a string? + +=item * How do I pad a string with blanks or pad a number with zeroes? + +=item * How do I extract selected columns from a string? + +=item * How do I find the soundex value of a string? + +=item * How can I expand variables in text strings? + +=item * What's wrong with always quoting "$vars"? + +=item * Why don't my EEHERE documents work? + +=item * What is the difference between a list and an array? + +=item * What is the difference between $array[1] and @array[1]? + +=item * How can I extract just the unique elements of an array? + +=item * How can I tell whether a list or array contains a certain element? + +=item * How do I compute the difference of two arrays? How do I compute the intersection of two arrays? + +=item * How do I test whether two arrays or hashes are equal? + +=item * How do I find the first array element for which a condition is true? + +=item * How do I handle linked lists? + +=item * How do I handle circular lists? + +=item * How do I shuffle an array randomly? + +=item * How do I process/modify each element of an array? + +=item * How do I select a random element from an array? + +=item * How do I permute N elements of a list? + +=item * How do I sort an array by (anything)? + +=item * How do I manipulate arrays of bits? + +=item * Why does defined() return true on empty arrays and hashes? + +=item * How do I process an entire hash? + +=item * What happens if I add or remove keys from a hash while iterating over it? + +=item * How do I look up a hash element by value? + +=item * How can I know how many entries are in a hash? + +=item * How do I sort a hash (optionally by value instead of key)? + +=item * How can I always keep my hash sorted? + +=item * What's the difference between "delete" and "undef" with hashes? + +=item * Why don't my tied hashes make the defined/exists distinction? + +=item * How do I reset an each() operation part-way through? + +=item * How can I get the unique keys from two hashes? + +=item * How can I store a multidimensional array in a DBM file? + +=item * How can I make my hash remember the order I put elements into it? + +=item * Why does passing a subroutine an undefined element in a hash create it? + +=item * How can I make the Perl equivalent of a C structure/C++ class/hash or array of hashes or arrays? + +=item * How can I use a reference as a hash key? + +=item * How do I handle binary data correctly? + +=item * How do I determine whether a scalar is a number/whole/integer/float? + +=item * How do I keep persistent data across program calls? + +=item * How do I print out or copy a recursive data structure? + +=item * How do I define methods for every class/object? + +=item * How do I verify a credit card checksum? + +=item * How do I pack arrays of doubles or floats for XS code? + +=back + + =item L: Files and Formats I/O and the "f" issues: filehandles, flushing, formats and footers. +=over 4 + +=item * How do I flush/unbuffer an output filehandle? Why must I do this? + +=item * How do I change one line in a file/delete a line in a file/insert a line in the middle of a file/append to the beginning of a file? + +=item * How do I count the number of lines in a file? + +=item * How do I make a temporary file name? + +=item * How can I manipulate fixed-record-length files? + +=item * How can I make a filehandle local to a subroutine? How do I pass filehandles between subroutines? How do I make an array of filehandles? + +=item * How can I use a filehandle indirectly? + +=item * How can I set up a footer format to be used with write()? + +=item * How can I write() into a string? + +=item * How can I output my numbers with commas added? + +=item * How can I translate tildes (~) in a filename? + +=item * How come when I open a file read-write it wipes it out? + +=item * Why do I sometimes get an "Argument list too long" when I use E*E? + +=item * Is there a leak/bug in glob()? + +=item * How can I open a file with a leading "E" or trailing blanks? + +=item * How can I reliably rename a file? + +=item * How can I lock a file? + +=item * Why can't I just open(FH, ">file.lock")? + +=item * I still don't get locking. I just want to increment the number in the file. How can I do this? + +=item * How do I randomly update a binary file? + +=item * How do I get a file's timestamp in perl? + +=item * How do I set a file's timestamp in perl? + +=item * How do I print to more than one file at once? + +=item * How can I read in a file by paragraphs? + +=item * How can I read a single character from a file? From the keyboard? + +=item * How can I tell whether there's a character waiting on a filehandle? + +=item * How do I do a C in perl? + +=item * How do I dup() a filehandle in Perl? + +=item * How do I close a file descriptor by number? + +=item * Why can't I use "C:\temp\foo" in DOS paths? What doesn't `C:\temp\foo.exe` work? + +=item * Why doesn't glob("*.*") get all the files? + +=item * Why does Perl let me delete read-only files? Why does C<-i> clobber protected files? Isn't this a bug in Perl? + +=item * How do I select a random line from a file? + +=item * Why do I get weird spaces when I print an array of lines? + +=back + + =item L: Regexps Pattern matching and regular expressions. +=over 4 + +=item * How can I hope to use regular expressions without creating illegible and unmaintainable code? + +=item * I'm having trouble matching over more than one line. What's wrong? + +=item * How can I pull out lines between two patterns that are themselves on different lines? + +=item * I put a regular expression into $/ but it didn't work. What's wrong? + +=item * How do I substitute case insensitively on the LHS, but preserving case on the RHS? + +=item * How can I make C<\w> match national character sets? + +=item * How can I match a locale-smart version of C? + +=item * How can I quote a variable to use in a regexp? + +=item * What is C really for? + +=item * How do I use a regular expression to strip C style comments from a file? + +=item * Can I use Perl regular expressions to match balanced text? + +=item * What does it mean that regexps are greedy? How can I get around it? + +=item * How do I process each word on each line? + +=item * How can I print out a word-frequency or line-frequency summary? + +=item * How can I do approximate matching? + +=item * How do I efficiently match many regular expressions at once? + +=item * Why don't word-boundary searches with C<\b> work for me? + +=item * Why does using $&, $`, or $' slow my program down? + +=item * What good is C<\G> in a regular expression? + +=item * Are Perl regexps DFAs or NFAs? Are they POSIX compliant? + +=item * What's wrong with using grep or map in a void context? + +=item * How can I match strings with multibyte characters? + +=item * How do I match a pattern that is supplied by the user? + +=back + + =item L: General Perl Language Issues General Perl language issues that don't clearly fit into any of the other sections. +=over 4 + +=item * Can I get a BNF/yacc/RE for the Perl language? + +=item * What are all these $@%* punctuation signs, and how do I know when to use them? + +=item * Do I always/never have to quote my strings or use semicolons and commas? + +=item * How do I skip some return values? + +=item * How do I temporarily block warnings? + +=item * What's an extension? + +=item * Why do Perl operators have different precedence than C operators? + +=item * How do I declare/create a structure? + +=item * How do I create a module? + +=item * How do I create a class? + +=item * How can I tell if a variable is tainted? + +=item * What's a closure? + +=item * What is variable suicide and how can I prevent it? + +=item * How can I pass/return a {Function, FileHandle, Array, Hash, Method, Regexp}? + +=item * How do I create a static variable? + +=item * What's the difference between dynamic and lexical (static) scoping? Between local() and my()? + +=item * How can I access a dynamic variable while a similarly named lexical is in scope? + +=item * What's the difference between deep and shallow binding? + +=item * Why doesn't "my($foo) = EFILEE;" work right? + +=item * How do I redefine a builtin function, operator, or method? + +=item * What's the difference between calling a function as &foo and foo()? + +=item * How do I create a switch or case statement? + +=item * How can I catch accesses to undefined variables/functions/methods? + +=item * Why can't a method included in this same file be found? + +=item * How can I find out my current package? + +=item * How can I comment out a large block of perl code? + +=item * How do I clear a package? + +=back + + =item L: System Interaction Interprocess communication (IPC), control over the user-interface (keyboard, screen and pointing devices). +=over 4 + +=item * How do I find out which operating system I'm running under? + +=item * How come exec() doesn't return? + +=item * How do I do fancy stuff with the keyboard/screen/mouse? + +=item * How do I print something out in color? + +=item * How do I read just one key without waiting for a return key? + +=item * How do I check whether input is ready on the keyboard? + +=item * How do I clear the screen? + +=item * How do I get the screen size? + +=item * How do I ask the user for a password? + +=item * How do I read and write the serial port? + +=item * How do I decode encrypted password files? + +=item * How do I start a process in the background? + +=item * How do I trap control characters/signals? + +=item * How do I modify the shadow password file on a Unix system? + +=item * How do I set the time and date? + +=item * How can I sleep() or alarm() for under a second? + +=item * How can I measure time under a second? + +=item * How can I do an atexit() or setjmp()/longjmp()? (Exception handling) + +=item * Why doesn't my sockets program work under System V (Solaris)? What does the error message "Protocol not supported" mean? + +=item * How can I call my system's unique C functions from Perl? + +=item * Where do I get the include files to do ioctl() or syscall()? + +=item * Why do setuid perl scripts complain about kernel problems? + +=item * How can I open a pipe both to and from a command? + +=item * Why can't I get the output of a command with system()? + +=item * How can I capture STDERR from an external command? + +=item * Why doesn't open() return an error when a pipe open fails? + +=item * What's wrong with using backticks in a void context? + +=item * How can I call backticks without shell processing? + +=item * Why can't my script read from STDIN after I gave it EOF (^D on Unix, ^Z on MS-DOS)? + +=item * How can I convert my shell script to perl? + +=item * Can I use perl to run a telnet or ftp session? + +=item * How can I write expect in Perl? + +=item * Is there a way to hide perl's command line from programs such as "ps"? + +=item * I {changed directory, modified my environment} in a perl script. How come the change disappeared when I exited the script? How do I get my changes to be visible? + +=item * How do I close a process's filehandle without waiting for it to complete? + +=item * How do I fork a daemon process? + +=item * How do I make my program run with sh and csh? + +=item * How do I find out if I'm running interactively or not? + +=item * How do I timeout a slow event? + +=item * How do I set CPU limits? + +=item * How do I avoid zombies on a Unix system? + +=item * How do I use an SQL database? + +=item * How do I make a system() exit on control-C? + +=item * How do I open a file without blocking? + +=item * How do I install a CPAN module? + +=item * What's the difference between require and use? + +=item * How do I keep my own module/library directory? + +=item * How do I add the directory my program lives in to the module/library search path? + +=item * How do I add a directory to my include path at runtime? + +=item * What is socket.ph and where do I get it? + +=back + + =item L: Networking Networking, the Internet, and a few on the web. +=over 4 + +=item * My CGI script runs from the command line but not the browser. (500 Server Error) + +=item * How can I get better error messages from a CGI program? + +=item * How do I remove HTML from a string? + +=item * How do I extract URLs? + +=item * How do I download a file from the user's machine? How do I open a file on another machine? + +=item * How do I make a pop-up menu in HTML? + +=item * How do I fetch an HTML file? + +=item * How do I automate an HTML form submission? + +=item * How do I decode or create those %-encodings on the web? + +=item * How do I redirect to another page? + +=item * How do I put a password on my web pages? + +=item * How do I edit my .htpasswd and .htgroup files with Perl? + +=item * How do I make sure users can't enter values into a form that cause my CGI script to do bad things? + +=item * How do I parse a mail header? + +=item * How do I decode a CGI form? + +=item * How do I check a valid mail address? + +=item * How do I decode a MIME/BASE64 string? + +=item * How do I return the user's mail address? + +=item * How do I send mail? + +=item * How do I read mail? + +=item * How do I find out my hostname/domainname/IP address? + +=item * How do I fetch a news article or the active newsgroups? + +=item * How do I fetch/put an FTP file? + +=item * How can I do RPC in Perl? + +=back + + =back =head2 Where to get this document @@ -66,6 +706,7 @@ at http://www.perl.com/perl/faq/ . You may mail corrections, additions, and suggestions to perlfaq-suggestions@perl.com . This alias should not be used to I FAQs. It's for fixing the current FAQ. +Send questions to the comp.lang.perl.misc newsgroup. =head2 What will happen if you mail your Perl programming problems to the authors @@ -88,7 +729,7 @@ Perl Porters. =head1 Author and Copyright Information -Copyright (c) 1997, 1998 Tom Christiansen and Nathan Torkington. +Copyright (c) 1997-1999 Tom Christiansen and Nathan Torkington. All rights reserved. =head2 Bundled Distributions @@ -117,6 +758,11 @@ in respect of this information or its use. =over 4 +=item 7/January/99 + +Small touchups here and there. Added all questions in this +document as a sort of table of contents. + =item 22/June/98 Significant changes throughout in preparation for the 5.005 @@ -170,3 +816,4 @@ This is the initial release of version 3 of the FAQ; consequently there have been no changes since its initial release. =back + diff --git a/pod/perlfaq1.pod b/pod/perlfaq1.pod index c6d53b3..6a752b9 100644 --- a/pod/perlfaq1.pod +++ b/pod/perlfaq1.pod @@ -1,6 +1,6 @@ =head1 NAME -perlfaq1 - General Questions About Perl ($Revision: 1.15 $, $Date: 1998/08/05 11:52:24 $) +perlfaq1 - General Questions About Perl ($Revision: 1.20 $, $Date: 1999/01/08 04:22:09 $) =head1 DESCRIPTION @@ -32,12 +32,14 @@ the personal note at the end of the README file in the perl source distribution for more details. See L (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 news://news.perl.com/perl.porters-gw/ and -http://www.frii.com/~gnat/perl/porters/summary.html. +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 News archive at +http://www.dejanews.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 @@ -51,12 +53,16 @@ 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. The most -recent production release is 5.005_01. Further references to the Perl -language in this document refer to this production release unless -otherwise specified. There may be one or more official bug fixes for -5.005_01 by the time you read this, and also perhaps some experimental -versions on the way to the next release. +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 5.005_02 (although 5.004_04 is still supported). +The most cutting-edge development release is 5.005_54. 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 for 5.005_02 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? @@ -68,11 +74,12 @@ 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 complete rewrite of the perl source -code from the ground up. 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. +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 @@ -80,6 +87,27 @@ simply use "perl" to refer to the latest version of perl and avoid using See L for a history of Perl revisions. +=head2 What is perl6? + +Perl6 is a semi-jocular reference to the Topaz project. Headed by Chip +Salzenberg, Topaz is yet-another ground-up rewrite of the current release +of Perl, one whose major goal is to create a more maintainable core than +found in release 5. Written in nominally portable C++, Topaz hopes to +maintain 100% source-compatibility with previous releases of Perl but to +run significantly faster and smaller. The Topaz team hopes to provide +an XS compatibility interface to allow most XS modules to work unchanged, +albeit perhaps without the efficiency that the new interface uowld allow. +New features in Topaz are as yet undetermined, and will be addressed +once compatibility and performance goals are met. + +If you are a hard-working C++ wizard with a firm command of Perl's +internals, and you would like to work on the project, send a request to +perl6-porters-request@perl.org to subscribe to the Topaz mailing list. + +There is no ETA for Topaz. It is expected to be several years before it +achieves enough robustness, compatibility, portability, and performance +to replace perl5 for ordinary use by mere mortals. + =head2 How stable is Perl? Production releases, which incorporate bug fixes and new functionality, @@ -106,18 +134,18 @@ 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, Perl is (frequently) an interpreted language. This means -that 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. +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 the CPAN, which is +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? @@ -130,22 +158,25 @@ 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 almost any -task, from one-line file-processing tasks to complex 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. +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. +to create a powerful application. See L. That said, there will always be small, focused, special-purpose languages dedicated to a specific problem domain that are simply more @@ -164,17 +195,16 @@ 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 multithreaded +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 reduce the limitations given -in the previous statement to some degree, but understand that Perl -remains fundamentally a dynamically typed language, and not a -statically typed one. You certainly won't be chastized 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. :-) +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"? @@ -183,33 +213,58 @@ 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. +ok, while "awk and Perl" and "Python and perl" do not. But never +write "PERL", because perl isn't really an acronym, aprocryphal +folklore and post-facto expansions notwithstanding. =head2 Is it a Perl program or a Perl script? -It doesn't matter. - -In "standard terminology" a I has been compiled to physical -machine code once, and can then be be run multiple times, whereas a -I