Adding upstream version 4.22.0.upstream/4.22.0

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1161 insertions, 0 deletions

diff --git a/upstream/debian-unstable/man1/perlfaq3.1 b/upstream/debian-unstable/man1/perlfaq3.1
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+.\" Automatically generated by Pod::Man 5.01 (Pod::Simple 3.43)
+.\"
+.\" Standard preamble:
+.\" ========================================================================
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+.if n .sp
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+.de Ve \" End verbatim text
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+.    ds C' ""
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+.    ds C`
+.    ds C'
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+.\"
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+.ie \n(.g .ds Aq \(aq
+.el       .ds Aq '
+.\"
+.\" If the F register is >0, we'll generate index entries on stderr for
+.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
+.\" entries marked with X<> in POD.  Of course, you'll have to process the
+.\" output yourself in some meaningful fashion.
+.\"
+.\" Avoid warning from groff about undefined register 'F'.
+.de IX
+..
+.nr rF 0
+.if \n(.g .if rF .nr rF 1
+.if (\n(rF:(\n(.g==0)) \{\
+.    if \nF \{\
+.        de IX
+.        tm Index:\\$1\t\\n%\t"\\$2"
+..
+.        if !\nF==2 \{\
+.            nr % 0
+.            nr F 2
+.        \}
+.    \}
+.\}
+.rr rF
+.\" ========================================================================
+.\"
+.IX Title "PERLFAQ3 1"
+.TH PERLFAQ3 1 2024-01-12 "perl v5.38.2" "Perl Programmers Reference Guide"
+.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
+.\" way too many mistakes in technical documents.
+.if n .ad l
+.nh
+.SH NAME
+perlfaq3 \- Programming Tools
+.SH VERSION
+.IX Header "VERSION"
+version 5.20210520
+.SH DESCRIPTION
+.IX Header "DESCRIPTION"
+This section of the FAQ answers questions related to programmer tools
+and programming support.
+.SS "How do I do (anything)?"
+.IX Subsection "How do I do (anything)?"
+Have you looked at CPAN (see perlfaq2)? The chances are that
+someone has already written a module that can solve your problem.
+Have you read the appropriate manpages? Here's a brief index:
+.IP Basics 4
+.IX Item "Basics"
+.RS 4
+.PD 0
+.IP "perldata \- Perl data types" 4
+.IX Item "perldata - Perl data types"
+.IP "perlvar \- Perl pre-defined variables" 4
+.IX Item "perlvar - Perl pre-defined variables"
+.IP "perlsyn \- Perl syntax" 4
+.IX Item "perlsyn - Perl syntax"
+.IP "perlop \- Perl operators and precedence" 4
+.IX Item "perlop - Perl operators and precedence"
+.IP "perlsub \- Perl subroutines" 4
+.IX Item "perlsub - Perl subroutines"
+.RE
+.RS 4
+.RE
+.IP Execution 4
+.IX Item "Execution"
+.RS 4
+.IP "perlrun \- how to execute the Perl interpreter" 4
+.IX Item "perlrun - how to execute the Perl interpreter"
+.IP "perldebug \- Perl debugging" 4
+.IX Item "perldebug - Perl debugging"
+.RE
+.RS 4
+.RE
+.IP Functions 4
+.IX Item "Functions"
+.RS 4
+.IP "perlfunc \- Perl builtin functions" 4
+.IX Item "perlfunc - Perl builtin functions"
+.RE
+.RS 4
+.RE
+.IP Objects 4
+.IX Item "Objects"
+.RS 4
+.IP "perlref \- Perl references and nested data structures" 4
+.IX Item "perlref - Perl references and nested data structures"
+.IP "perlmod \- Perl modules (packages and symbol tables)" 4
+.IX Item "perlmod - Perl modules (packages and symbol tables)"
+.IP "perlobj \- Perl objects" 4
+.IX Item "perlobj - Perl objects"
+.IP "perltie \- how to hide an object class in a simple variable" 4
+.IX Item "perltie - how to hide an object class in a simple variable"
+.RE
+.RS 4
+.RE
+.IP "Data Structures" 4
+.IX Item "Data Structures"
+.RS 4
+.IP "perlref \- Perl references and nested data structures" 4
+.IX Item "perlref - Perl references and nested data structures"
+.IP "perllol \- Manipulating arrays of arrays in Perl" 4
+.IX Item "perllol - Manipulating arrays of arrays in Perl"
+.IP "perldsc \- Perl Data Structures Cookbook" 4
+.IX Item "perldsc - Perl Data Structures Cookbook"
+.RE
+.RS 4
+.RE
+.IP Modules 4
+.IX Item "Modules"
+.RS 4
+.IP "perlmod \- Perl modules (packages and symbol tables)" 4
+.IX Item "perlmod - Perl modules (packages and symbol tables)"
+.IP "perlmodlib \- constructing new Perl modules and finding existing ones" 4
+.IX Item "perlmodlib - constructing new Perl modules and finding existing ones"
+.RE
+.RS 4
+.RE
+.IP Regexes 4
+.IX Item "Regexes"
+.RS 4
+.IP "perlre \- Perl regular expressions" 4
+.IX Item "perlre - Perl regular expressions"
+.IP "perlfunc \- Perl builtin functions>" 4
+.IX Item "perlfunc - Perl builtin functions>"
+.IP "perlop \- Perl operators and precedence" 4
+.IX Item "perlop - Perl operators and precedence"
+.IP "perllocale \- Perl locale handling (internationalization and localization)" 4
+.IX Item "perllocale - Perl locale handling (internationalization and localization)"
+.RE
+.RS 4
+.RE
+.IP "Moving to perl5" 4
+.IX Item "Moving to perl5"
+.RS 4
+.IP "perltrap \- Perl traps for the unwary" 4
+.IX Item "perltrap - Perl traps for the unwary"
+.IP perl 4
+.IX Item "perl"
+.RE
+.RS 4
+.RE
+.IP "Linking with C" 4
+.IX Item "Linking with C"
+.RS 4
+.IP "perlxstut \- Tutorial for writing XSUBs" 4
+.IX Item "perlxstut - Tutorial for writing XSUBs"
+.IP "perlxs \- XS language reference manual" 4
+.IX Item "perlxs - XS language reference manual"
+.IP "perlcall \- Perl calling conventions from C" 4
+.IX Item "perlcall - Perl calling conventions from C"
+.IP "perlguts \- Introduction to the Perl API" 4
+.IX Item "perlguts - Introduction to the Perl API"
+.IP "perlembed \- how to embed perl in your C program" 4
+.IX Item "perlembed - how to embed perl in your C program"
+.RE
+.RS 4
+.RE
+.IP Various 4
+.IX Item "Various"
+.PD
+<http://www.cpan.org/misc/olddoc/FMTEYEWTK.tgz>
+(not a man-page but still useful, a collection of various essays on
+Perl techniques)
+.PP
+A crude table of contents for the Perl manpage set is found in perltoc.
+.SS "How can I use Perl interactively?"
+.IX Subsection "How can I use Perl interactively?"
+The typical approach uses the Perl debugger, described in the
+\&\fBperldebug\fR\|(1) manpage, on an "empty" program, like this:
+.PP
+.Vb 1
+\&    perl \-de 42
+.Ve
+.PP
+Now just type in any legal Perl code, and it will be immediately
+evaluated. You can also examine the symbol table, get stack
+backtraces, check variable values, set breakpoints, and other
+operations typically found in symbolic debuggers.
+.PP
+You can also use Devel::REPL which is an interactive shell for Perl,
+commonly known as a REPL \- Read, Evaluate, Print, Loop. It provides
+various handy features.
+.SS "How do I find which modules are installed on my system?"
+.IX Subsection "How do I find which modules are installed on my system?"
+From the command line, you can use the \f(CW\*(C`cpan\*(C'\fR command's \f(CW\*(C`\-l\*(C'\fR switch:
+.PP
+.Vb 1
+\&    $ cpan \-l
+.Ve
+.PP
+You can also use \f(CW\*(C`cpan\*(C'\fR's \f(CW\*(C`\-a\*(C'\fR switch to create an autobundle file
+that \f(CW\*(C`CPAN.pm\*(C'\fR understands and can use to re-install every module:
+.PP
+.Vb 1
+\&    $ cpan \-a
+.Ve
+.PP
+Inside a Perl program, you can use the ExtUtils::Installed module to
+show all installed distributions, although it can take awhile to do
+its magic. The standard library which comes with Perl just shows up
+as "Perl" (although you can get those with Module::CoreList).
+.PP
+.Vb 1
+\&    use ExtUtils::Installed;
+\&
+\&    my $inst    = ExtUtils::Installed\->new();
+\&    my @modules = $inst\->modules();
+.Ve
+.PP
+If you want a list of all of the Perl module filenames, you
+can use File::Find::Rule:
+.PP
+.Vb 1
+\&    use File::Find::Rule;
+\&
+\&    my @files = File::Find::Rule\->
+\&        extras({follow => 1})\->
+\&        file()\->
+\&        name( \*(Aq*.pm\*(Aq )\->
+\&        in( @INC )
+\&        ;
+.Ve
+.PP
+If you do not have that module, you can do the same thing
+with File::Find which is part of the standard library:
+.PP
+.Vb 2
+\&    use File::Find;
+\&    my @files;
+\&
+\&    find(
+\&        {
+\&        wanted => sub {
+\&            push @files, $File::Find::fullname
+\&            if \-f $File::Find::fullname && /\e.pm$/
+\&        },
+\&        follow => 1,
+\&        follow_skip => 2,
+\&        },
+\&        @INC
+\&    );
+\&
+\&    print join "\en", @files;
+.Ve
+.PP
+If you simply need to check quickly to see if a module is
+available, you can check for its documentation. If you can
+read the documentation the module is most likely installed.
+If you cannot read the documentation, the module might not
+have any (in rare cases):
+.PP
+.Vb 1
+\&    $ perldoc Module::Name
+.Ve
+.PP
+You can also try to include the module in a one-liner to see if
+perl finds it:
+.PP
+.Vb 1
+\&    $ perl \-MModule::Name \-e1
+.Ve
+.PP
+(If you don't receive a "Can't locate ... in \f(CW@INC\fR" error message, then Perl
+found the module name you asked for.)
+.SS "How do I debug my Perl programs?"
+.IX Subsection "How do I debug my Perl programs?"
+(contributed by brian d foy)
+.PP
+Before you do anything else, you can help yourself by ensuring that
+you let Perl tell you about problem areas in your code. By turning
+on warnings and strictures, you can head off many problems before
+they get too big. You can find out more about these in strict
+and warnings.
+.PP
+.Vb 3
+\&    #!/usr/bin/perl
+\&    use strict;
+\&    use warnings;
+.Ve
+.PP
+Beyond that, the simplest debugger is the \f(CW\*(C`print\*(C'\fR function. Use it
+to look at values as you run your program:
+.PP
+.Vb 1
+\&    print STDERR "The value is [$value]\en";
+.Ve
+.PP
+The Data::Dumper module can pretty-print Perl data structures:
+.PP
+.Vb 2
+\&    use Data::Dumper qw( Dumper );
+\&    print STDERR "The hash is " . Dumper( \e%hash ) . "\en";
+.Ve
+.PP
+Perl comes with an interactive debugger, which you can start with the
+\&\f(CW\*(C`\-d\*(C'\fR switch. It's fully explained in perldebug.
+.PP
+If you'd like a graphical user interface and you have Tk, you can use
+\&\f(CW\*(C`ptkdb\*(C'\fR. It's on CPAN and available for free.
+.PP
+If you need something much more sophisticated and controllable, Leon
+Brocard's Devel::ebug (which you can call with the \f(CW\*(C`\-D\*(C'\fR switch as \f(CW\*(C`\-Debug\*(C'\fR)
+gives you the programmatic hooks into everything you need to write your
+own (without too much pain and suffering).
+.PP
+You can also use a commercial debugger such as Affrus (Mac OS X), Komodo
+from Activestate (Windows and Mac OS X), or EPIC (most platforms).
+.SS "How do I profile my Perl programs?"
+.IX Subsection "How do I profile my Perl programs?"
+(contributed by brian d foy, updated Fri Jul 25 12:22:26 PDT 2008)
+.PP
+The \f(CW\*(C`Devel\*(C'\fR namespace has several modules which you can use to
+profile your Perl programs.
+.PP
+The Devel::NYTProf (New York Times Profiler) does both statement
+and subroutine profiling. It's available from CPAN and you also invoke
+it with the \f(CW\*(C`\-d\*(C'\fR switch:
+.PP
+.Vb 1
+\&    perl \-d:NYTProf some_perl.pl
+.Ve
+.PP
+It creates a database of the profile information that you can turn into
+reports. The \f(CW\*(C`nytprofhtml\*(C'\fR command turns the data into an HTML report
+similar to the Devel::Cover report:
+.PP
+.Vb 1
+\&    nytprofhtml
+.Ve
+.PP
+You might also be interested in using the Benchmark to
+measure and compare code snippets.
+.PP
+You can read more about profiling in \fIProgramming Perl\fR, chapter 20,
+or \fIMastering Perl\fR, chapter 5.
+.PP
+perldebguts documents creating a custom debugger if you need to
+create a special sort of profiler. brian d foy describes the process
+in \fIThe Perl Journal\fR, "Creating a Perl Debugger",
+<http://www.ddj.com/184404522> , and "Profiling in Perl"
+<http://www.ddj.com/184404580> .
+.PP
+Perl.com has two interesting articles on profiling: "Profiling Perl",
+by Simon Cozens, <https://www.perl.com/pub/2004/06/25/profiling.html/>
+and "Debugging and Profiling mod_perl Applications", by Frank Wiles,
+<http://www.perl.com/pub/a/2006/02/09/debug_mod_perl.html> .
+.PP
+Randal L. Schwartz writes about profiling in "Speeding up Your Perl
+Programs" for \fIUnix Review\fR,
+<http://www.stonehenge.com/merlyn/UnixReview/col49.html> , and "Profiling
+in Template Toolkit via Overriding" for \fILinux Magazine\fR,
+<http://www.stonehenge.com/merlyn/LinuxMag/col75.html> .
+.SS "How do I cross-reference my Perl programs?"
+.IX Subsection "How do I cross-reference my Perl programs?"
+The B::Xref module can be used to generate cross-reference reports
+for Perl programs.
+.PP
+.Vb 1
+\&    perl \-MO=Xref[,OPTIONS] scriptname.plx
+.Ve
+.SS "Is there a pretty-printer (formatter) for Perl?"
+.IX Subsection "Is there a pretty-printer (formatter) for Perl?"
+Perl::Tidy comes with a perl script perltidy which indents and
+reformats Perl scripts to make them easier to read by trying to follow
+the rules of the perlstyle. If you write Perl, or spend much time reading
+Perl, you will probably find it useful.
+.PP
+Of course, if you simply follow the guidelines in perlstyle,
+you shouldn't need to reformat. The habit of formatting your code
+as you write it will help prevent bugs. Your editor can and should
+help you with this. The perl-mode or newer cperl-mode for emacs
+can provide remarkable amounts of help with most (but not all)
+code, and even less programmable editors can provide significant
+assistance. Tom Christiansen and many other VI users swear by
+the following settings in vi and its clones:
+.PP
+.Vb 2
+\&    set ai sw=4
+\&    map! ^O {^M}^[O^T
+.Ve
+.PP
+Put that in your \fI.exrc\fR file (replacing the caret characters
+with control characters) and away you go. In insert mode, ^T is
+for indenting, ^D is for undenting, and ^O is for blockdenting\-\-as
+it were. A more complete example, with comments, can be found at
+<http://www.cpan.org/authors/id/T/TO/TOMC/scripts/toms.exrc.gz>
+.SS "Is there an IDE or Windows Perl Editor?"
+.IX Subsection "Is there an IDE or Windows Perl Editor?"
+Perl programs are just plain text, so any editor will do.
+.PP
+If you're on Unix, you already have an IDE\-\-Unix itself. The Unix
+philosophy is the philosophy of several small tools that each do one
+thing and do it well. It's like a carpenter's toolbox.
+.PP
+If you want an IDE, check the following (in alphabetical order, not
+order of preference):
+.IP Eclipse 4
+.IX Item "Eclipse"
+<http://e\-p\-i\-c.sf.net/>
+.Sp
+The Eclipse Perl Integration Project integrates Perl
+editing/debugging with Eclipse.
+.IP Enginsite 4
+.IX Item "Enginsite"
+<http://www.enginsite.com/>
+.Sp
+Perl Editor by EngInSite is a complete integrated development
+environment (IDE) for creating, testing, and  debugging  Perl scripts;
+the tool runs on Windows 9x/NT/2000/XP or later.
+.IP "IntelliJ IDEA" 4
+.IX Item "IntelliJ IDEA"
+<https://plugins.jetbrains.com/plugin/7796>
+.Sp
+Camelcade plugin provides Perl5 support in IntelliJ IDEA and other JetBrains IDEs.
+.IP Kephra 4
+.IX Item "Kephra"
+<http://kephra.sf.net>
+.Sp
+GUI editor written in Perl using wxWidgets and Scintilla with lots of smaller features.
+Aims for a UI based on Perl principles like TIMTOWTDI and "easy things should be easy,
+hard things should be possible".
+.IP Komodo 4
+.IX Item "Komodo"
+<http://www.ActiveState.com/Products/Komodo/>
+.Sp
+ActiveState's cross-platform (as of October 2004, that's Windows, Linux,
+and Solaris), multi-language IDE has Perl support, including a regular expression
+debugger and remote debugging.
+.IP Notepad++ 4
+.IX Item "Notepad++"
+<http://notepad\-plus.sourceforge.net/>
+.IP "Open Perl IDE" 4
+.IX Item "Open Perl IDE"
+<http://open\-perl\-ide.sourceforge.net/>
+.Sp
+Open Perl IDE is an integrated development environment for writing
+and debugging Perl scripts with ActiveState's ActivePerl distribution
+under Windows 95/98/NT/2000.
+.IP OptiPerl 4
+.IX Item "OptiPerl"
+<http://www.optiperl.com/>
+.Sp
+OptiPerl is a Windows IDE with simulated CGI environment, including
+debugger and syntax-highlighting editor.
+.IP Padre 4
+.IX Item "Padre"
+<http://padre.perlide.org/>
+.Sp
+Padre is cross-platform IDE for Perl written in Perl using wxWidgets to provide
+a native look and feel. It's open source under the Artistic License. It
+is one of the newer Perl IDEs.
+.IP PerlBuilder 4
+.IX Item "PerlBuilder"
+<http://www.solutionsoft.com/perl.htm>
+.Sp
+PerlBuilder is an integrated development environment for Windows that
+supports Perl development.
+.IP visiPerl+ 4
+.IX Item "visiPerl+"
+<http://helpconsulting.net/visiperl/index.html>
+.Sp
+From Help Consulting, for Windows.
+.IP "Visual Perl" 4
+.IX Item "Visual Perl"
+<http://www.activestate.com/Products/Visual_Perl/>
+.Sp
+Visual Perl is a Visual Studio.NET plug-in from ActiveState.
+.IP Zeus 4
+.IX Item "Zeus"
+<http://www.zeusedit.com/lookmain.html>
+.Sp
+Zeus for Windows is another Win32 multi-language editor/IDE
+that comes with support for Perl.
+.PP
+For editors: if you're on Unix you probably have vi or a vi clone
+already, and possibly an emacs too, so you may not need to download
+anything. In any emacs the cperl-mode (M\-x cperl-mode) gives you
+perhaps the best available Perl editing mode in any editor.
+.PP
+If you are using Windows, you can use any editor that lets you work
+with plain text, such as NotePad or WordPad. Word processors, such as
+Microsoft Word or WordPerfect, typically do not work since they insert
+all sorts of behind-the-scenes information, although some allow you to
+save files as "Text Only". You can also download text editors designed
+specifically for programming, such as Textpad (
+<http://www.textpad.com/> ) and UltraEdit ( <http://www.ultraedit.com/> ),
+among others.
+.PP
+If you are using MacOS, the same concerns apply. MacPerl (for Classic
+environments) comes with a simple editor. Popular external editors are
+BBEdit ( <http://www.barebones.com/products/bbedit/> ) or Alpha (
+<http://www.his.com/~jguyer/Alpha/Alpha8.html> ). MacOS X users can use
+Unix editors as well.
+.IP "GNU Emacs" 4
+.IX Item "GNU Emacs"
+<http://www.gnu.org/software/emacs/windows/ntemacs.html>
+.IP MicroEMACS 4
+.IX Item "MicroEMACS"
+<http://www.microemacs.de/>
+.IP XEmacs 4
+.IX Item "XEmacs"
+<http://www.xemacs.org/Download/index.html>
+.IP Jed 4
+.IX Item "Jed"
+<http://space.mit.edu/~davis/jed/>
+.PP
+or a vi clone such as
+.IP Vim 4
+.IX Item "Vim"
+<http://www.vim.org/>
+.IP Vile 4
+.IX Item "Vile"
+<http://invisible\-island.net/vile/vile.html>
+.PP
+The following are Win32 multilanguage editor/IDEs that support Perl:
+.IP MultiEdit 4
+.IX Item "MultiEdit"
+<http://www.MultiEdit.com/>
+.IP SlickEdit 4
+.IX Item "SlickEdit"
+<http://www.slickedit.com/>
+.IP ConTEXT 4
+.IX Item "ConTEXT"
+<http://www.contexteditor.org/>
+.PP
+There is also a toyedit Text widget based editor written in Perl
+that is distributed with the Tk module on CPAN. The ptkdb
+( <http://ptkdb.sourceforge.net/> ) is a Perl/Tk\-based debugger that
+acts as a development environment of sorts. Perl Composer
+( <http://perlcomposer.sourceforge.net/> ) is an IDE for Perl/Tk
+GUI creation.
+.PP
+In addition to an editor/IDE you might be interested in a more
+powerful shell environment for Win32. Your options include
+.IP bash 4
+.IX Item "bash"
+from the Cygwin package ( <http://cygwin.com/> )
+.IP zsh 4
+.IX Item "zsh"
+<http://www.zsh.org/>
+.PP
+Cygwin is covered by the GNU General Public
+License (but that shouldn't matter for Perl use). Cygwin
+contains (in addition to the shell) a comprehensive set
+of standard Unix toolkit utilities.
+.IP "BBEdit and TextWrangler" 4
+.IX Item "BBEdit and TextWrangler"
+are text editors for OS X that have a Perl sensitivity mode
+( <http://www.barebones.com/> ).
+.SS "Where can I get Perl macros for vi?"
+.IX Subsection "Where can I get Perl macros for vi?"
+For a complete version of Tom Christiansen's vi configuration file,
+see <http://www.cpan.org/authors/id/T/TO/TOMC/scripts/toms.exrc.gz> ,
+the standard benchmark file for vi emulators. The file runs best with nvi,
+the current version of vi out of Berkeley, which incidentally can be built
+with an embedded Perl interpreter\-\-see <http://www.cpan.org/src/misc/> .
+.SS "Where can I get perl-mode or cperl-mode for emacs?"
+.IX Xref "emacs"
+.IX Subsection "Where can I get perl-mode or cperl-mode for emacs?"
+Since Emacs version 19 patchlevel 22 or so, there have been both a
+perl\-mode.el and support for the Perl debugger built in. These should
+come with the standard Emacs 19 distribution.
+.PP
+Note that the perl-mode of emacs will have fits with \f(CW"main\*(Aqfoo"\fR
+(single quote), and mess up the indentation and highlighting. You
+are probably using \f(CW"main::foo"\fR in new Perl code anyway, so this
+shouldn't be an issue.
+.PP
+For CPerlMode, see <http://www.emacswiki.org/cgi\-bin/wiki/CPerlMode>
+.SS "How can I use curses with Perl?"
+.IX Subsection "How can I use curses with Perl?"
+The Curses module from CPAN provides a dynamically loadable object
+module interface to a curses library. A small demo can be found at the
+directory <http://www.cpan.org/authors/id/T/TO/TOMC/scripts/rep.gz> ;
+this program repeats a command and updates the screen as needed, rendering
+\&\fBrep ps axu\fR similar to \fBtop\fR.
+.SS "How can I write a GUI (X, Tk, Gtk, etc.) in Perl?"
+.IX Xref "GUI Tk Wx WxWidgets Gtk Gtk2 CamelBones Qt"
+.IX Subsection "How can I write a GUI (X, Tk, Gtk, etc.) in Perl?"
+(contributed by Ben Morrow)
+.PP
+There are a number of modules which let you write GUIs in Perl. Most
+GUI toolkits have a perl interface: an incomplete list follows.
+.IP Tk 4
+.IX Item "Tk"
+This works under Unix and Windows, and the current version doesn't
+look half as bad under Windows as it used to. Some of the gui elements
+still don't 'feel' quite right, though. The interface is very natural
+and 'perlish', making it easy to use in small scripts that just need a
+simple gui. It hasn't been updated in a while.
+.IP Wx 4
+.IX Item "Wx"
+This is a Perl binding for the cross-platform wxWidgets toolkit
+( <http://www.wxwidgets.org> ). It works under Unix, Win32 and Mac OS X,
+using native widgets (Gtk under Unix). The interface follows the C++
+interface closely, but the documentation is a little sparse for someone
+who doesn't know the library, mostly just referring you to the C++
+documentation.
+.IP "Gtk and Gtk2" 4
+.IX Item "Gtk and Gtk2"
+These are Perl bindings for the Gtk toolkit ( <http://www.gtk.org> ). The
+interface changed significantly between versions 1 and 2 so they have
+separate Perl modules. It runs under Unix, Win32 and Mac OS X (currently
+it requires an X server on Mac OS, but a 'native' port is underway), and
+the widgets look the same on every platform: i.e., they don't match the
+native widgets. As with Wx, the Perl bindings follow the C API closely,
+and the documentation requires you to read the C documentation to
+understand it.
+.IP Win32::GUI 4
+.IX Item "Win32::GUI"
+This provides access to most of the Win32 GUI widgets from Perl.
+Obviously, it only runs under Win32, and uses native widgets. The Perl
+interface doesn't really follow the C interface: it's been made more
+Perlish, and the documentation is pretty good. More advanced stuff may
+require familiarity with the C Win32 APIs, or reference to MSDN.
+.IP CamelBones 4
+.IX Item "CamelBones"
+CamelBones ( <http://camelbones.sourceforge.net> ) is a Perl interface to
+Mac OS X's Cocoa GUI toolkit, and as such can be used to produce native
+GUIs on Mac OS X. It's not on CPAN, as it requires frameworks that
+CPAN.pm doesn't know how to install, but installation is via the
+standard OSX package installer. The Perl API is, again, very close to
+the ObjC API it's wrapping, and the documentation just tells you how to
+translate from one to the other.
+.IP Qt 4
+.IX Item "Qt"
+There is a Perl interface to TrollTech's Qt toolkit, but it does not
+appear to be maintained.
+.IP Athena 4
+.IX Item "Athena"
+Sx is an interface to the Athena widget set which comes with X, but
+again it appears not to be much used nowadays.
+.SS "How can I make my Perl program run faster?"
+.IX Subsection "How can I make my Perl program run faster?"
+The best way to do this is to come up with a better algorithm. This
+can often make a dramatic difference. Jon Bentley's book
+\&\fIProgramming Pearls\fR (that's not a misspelling!)  has some good tips
+on optimization, too. Advice on benchmarking boils down to: benchmark
+and profile to make sure you're optimizing the right part, look for
+better algorithms instead of microtuning your code, and when all else
+fails consider just buying faster hardware. You will probably want to
+read the answer to the earlier question "How do I profile my Perl
+programs?" if you haven't done so already.
+.PP
+A different approach is to autoload seldom-used Perl code. See the
+AutoSplit and AutoLoader modules in the standard distribution for
+that. Or you could locate the bottleneck and think about writing just
+that part in C, the way we used to take bottlenecks in C code and
+write them in assembler. Similar to rewriting in C, modules that have
+critical sections can be written in C (for instance, the PDL module
+from CPAN).
+.PP
+If you're currently linking your perl executable to a shared
+\&\fIlibc.so\fR, you can often gain a 10\-25% performance benefit by
+rebuilding it to link with a static libc.a instead. This will make a
+bigger perl executable, but your Perl programs (and programmers) may
+thank you for it. See the \fIINSTALL\fR file in the source distribution
+for more information.
+.PP
+The undump program was an ancient attempt to speed up Perl program by
+storing the already-compiled form to disk. This is no longer a viable
+option, as it only worked on a few architectures, and wasn't a good
+solution anyway.
+.SS "How can I make my Perl program take less memory?"
+.IX Subsection "How can I make my Perl program take less memory?"
+When it comes to time-space tradeoffs, Perl nearly always prefers to
+throw memory at a problem. Scalars in Perl use more memory than
+strings in C, arrays take more than that, and hashes use even more. While
+there's still a lot to be done, recent releases have been addressing
+these issues. For example, as of 5.004, duplicate hash keys are
+shared amongst all hashes using them, so require no reallocation.
+.PP
+In some cases, using \fBsubstr()\fR or \fBvec()\fR to simulate arrays can be
+highly beneficial. For example, an array of a thousand booleans will
+take at least 20,000 bytes of space, but it can be turned into one
+125\-byte bit vector\-\-a considerable memory savings. The standard
+Tie::SubstrHash module can also help for certain types of data
+structure. If you're working with specialist data structures
+(matrices, for instance) modules that implement these in C may use
+less memory than equivalent Perl modules.
+.PP
+Another thing to try is learning whether your Perl was compiled with
+the system malloc or with Perl's builtin malloc. Whichever one it
+is, try using the other one and see whether this makes a difference.
+Information about malloc is in the \fIINSTALL\fR file in the source
+distribution. You can find out whether you are using perl's malloc by
+typing \f(CW\*(C`perl \-V:usemymalloc\*(C'\fR.
+.PP
+Of course, the best way to save memory is to not do anything to waste
+it in the first place. Good programming practices can go a long way
+toward this:
+.IP "Don't slurp!" 4
+.IX Item "Don't slurp!"
+Don't read an entire file into memory if you can process it line
+by line. Or more concretely, use a loop like this:
+.Sp
+.Vb 6
+\&    #
+\&    # Good Idea
+\&    #
+\&    while (my $line = <$file_handle>) {
+\&       # ...
+\&    }
+.Ve
+.Sp
+instead of this:
+.Sp
+.Vb 7
+\&    #
+\&    # Bad Idea
+\&    #
+\&    my @data = <$file_handle>;
+\&    foreach (@data) {
+\&        # ...
+\&    }
+.Ve
+.Sp
+When the files you're processing are small, it doesn't much matter which
+way you do it, but it makes a huge difference when they start getting
+larger.
+.IP "Use map and grep selectively" 4
+.IX Item "Use map and grep selectively"
+Remember that both map and grep expect a LIST argument, so doing this:
+.Sp
+.Vb 1
+\&        @wanted = grep {/pattern/} <$file_handle>;
+.Ve
+.Sp
+will cause the entire file to be slurped. For large files, it's better
+to loop:
+.Sp
+.Vb 3
+\&        while (<$file_handle>) {
+\&                push(@wanted, $_) if /pattern/;
+\&        }
+.Ve
+.IP "Avoid unnecessary quotes and stringification" 4
+.IX Item "Avoid unnecessary quotes and stringification"
+Don't quote large strings unless absolutely necessary:
+.Sp
+.Vb 1
+\&        my $copy = "$large_string";
+.Ve
+.Sp
+makes 2 copies of \f(CW$large_string\fR (one for \f(CW$copy\fR and another for the
+quotes), whereas
+.Sp
+.Vb 1
+\&        my $copy = $large_string;
+.Ve
+.Sp
+only makes one copy.
+.Sp
+Ditto for stringifying large arrays:
+.Sp
+.Vb 4
+\&    {
+\&    local $, = "\en";
+\&    print @big_array;
+\&    }
+.Ve
+.Sp
+is much more memory-efficient than either
+.Sp
+.Vb 1
+\&    print join "\en", @big_array;
+.Ve
+.Sp
+or
+.Sp
+.Vb 4
+\&    {
+\&    local $" = "\en";
+\&    print "@big_array";
+\&    }
+.Ve
+.IP "Pass by reference" 4
+.IX Item "Pass by reference"
+Pass arrays and hashes by reference, not by value. For one thing, it's
+the only way to pass multiple lists or hashes (or both) in a single
+call/return. It also avoids creating a copy of all the contents. This
+requires some judgement, however, because any changes will be propagated
+back to the original data. If you really want to mangle (er, modify) a
+copy, you'll have to sacrifice the memory needed to make one.
+.IP "Tie large variables to disk" 4
+.IX Item "Tie large variables to disk"
+For "big" data stores (i.e. ones that exceed available memory) consider
+using one of the DB modules to store it on disk instead of in RAM. This
+will incur a penalty in access time, but that's probably better than
+causing your hard disk to thrash due to massive swapping.
+.SS "Is it safe to return a reference to local or lexical data?"
+.IX Subsection "Is it safe to return a reference to local or lexical data?"
+Yes. Perl's garbage collection system takes care of this so
+everything works out right.
+.PP
+.Vb 4
+\&    sub makeone {
+\&        my @a = ( 1 .. 10 );
+\&        return \e@a;
+\&    }
+\&
+\&    for ( 1 .. 10 ) {
+\&        push @many, makeone();
+\&    }
+\&
+\&    print $many[4][5], "\en";
+\&
+\&    print "@many\en";
+.Ve
+.SS "How can I free an array or hash so my program shrinks?"
+.IX Subsection "How can I free an array or hash so my program shrinks?"
+(contributed by Michael Carman)
+.PP
+You usually can't. Memory allocated to lexicals (i.e. \fBmy()\fR variables)
+cannot be reclaimed or reused even if they go out of scope. It is
+reserved in case the variables come back into scope. Memory allocated
+to global variables can be reused (within your program) by using
+\&\fBundef()\fR and/or \fBdelete()\fR.
+.PP
+On most operating systems, memory allocated to a program can never be
+returned to the system. That's why long-running programs sometimes re\-
+exec themselves. Some operating systems (notably, systems that use
+\&\fBmmap\fR\|(2) for allocating large chunks of memory) can reclaim memory that
+is no longer used, but on such systems, perl must be configured and
+compiled to use the OS's malloc, not perl's.
+.PP
+In general, memory allocation and de-allocation isn't something you can
+or should be worrying about much in Perl.
+.PP
+See also "How can I make my Perl program take less memory?"
+.SS "How can I make my CGI script more efficient?"
+.IX Subsection "How can I make my CGI script more efficient?"
+Beyond the normal measures described to make general Perl programs
+faster or smaller, a CGI program has additional issues. It may be run
+several times per second. Given that each time it runs it will need
+to be re-compiled and will often allocate a megabyte or more of system
+memory, this can be a killer. Compiling into C \fBisn't going to help
+you\fR because the process start-up overhead is where the bottleneck is.
+.PP
+There are three popular ways to avoid this overhead. One solution
+involves running the Apache HTTP server (available from
+<http://www.apache.org/> ) with either of the mod_perl or mod_fastcgi
+plugin modules.
+.PP
+With mod_perl and the Apache::Registry module (distributed with
+mod_perl), httpd will run with an embedded Perl interpreter which
+pre-compiles your script and then executes it within the same address
+space without forking. The Apache extension also gives Perl access to
+the internal server API, so modules written in Perl can do just about
+anything a module written in C can. For more on mod_perl, see
+<http://perl.apache.org/>
+.PP
+With the FCGI module (from CPAN) and the mod_fastcgi
+module (available from <http://www.fastcgi.com/> ) each of your Perl
+programs becomes a permanent CGI daemon process.
+.PP
+Finally, Plack is a Perl module and toolkit that contains PSGI middleware,
+helpers and adapters to web servers, allowing you to easily deploy scripts which
+can continue running, and provides flexibility with regards to which web server
+you use. It can allow existing CGI scripts to enjoy this flexibility and
+performance with minimal changes, or can be used along with modern Perl web
+frameworks to make writing and deploying web services with Perl a breeze.
+.PP
+These solutions can have far-reaching effects on your system and on the way you
+write your CGI programs, so investigate them with care.
+.PP
+See also
+<http://www.cpan.org/modules/by\-category/15_World_Wide_Web_HTML_HTTP_CGI/> .
+.SS "How can I hide the source for my Perl program?"
+.IX Subsection "How can I hide the source for my Perl program?"
+Delete it. :\-) Seriously, there are a number of (mostly
+unsatisfactory) solutions with varying levels of "security".
+.PP
+First of all, however, you \fIcan't\fR take away read permission, because
+the source code has to be readable in order to be compiled and
+interpreted. (That doesn't mean that a CGI script's source is
+readable by people on the web, though\-\-only by people with access to
+the filesystem.)  So you have to leave the permissions at the socially
+friendly 0755 level.
+.PP
+Some people regard this as a security problem. If your program does
+insecure things and relies on people not knowing how to exploit those
+insecurities, it is not secure. It is often possible for someone to
+determine the insecure things and exploit them without viewing the
+source. Security through obscurity, the name for hiding your bugs
+instead of fixing them, is little security indeed.
+.PP
+You can try using encryption via source filters (Starting from Perl
+5.8 the Filter::Simple and Filter::Util::Call modules are included in
+the standard distribution), but any decent programmer will be able to
+decrypt it. You can try using the byte code compiler and interpreter
+described later in perlfaq3, but the curious might still be able to
+de-compile it. You can try using the native-code compiler described
+later, but crackers might be able to disassemble it. These pose
+varying degrees of difficulty to people wanting to get at your code,
+but none can definitively conceal it (true of every language, not just
+Perl).
+.PP
+It is very easy to recover the source of Perl programs. You simply
+feed the program to the perl interpreter and use the modules in
+the B:: hierarchy. The B::Deparse module should be able to
+defeat most attempts to hide source. Again, this is not
+unique to Perl.
+.PP
+If you're concerned about people profiting from your code, then the
+bottom line is that nothing but a restrictive license will give you
+legal security. License your software and pepper it with threatening
+statements like "This is unpublished proprietary software of XYZ Corp.
+Your access to it does not give you permission to use it blah blah
+blah."  We are not lawyers, of course, so you should see a lawyer if
+you want to be sure your license's wording will stand up in court.
+.SS "How can I compile my Perl program into byte code or C?"
+.IX Subsection "How can I compile my Perl program into byte code or C?"
+(contributed by brian d foy)
+.PP
+In general, you can't do this. There are some things that may work
+for your situation though. People usually ask this question
+because they want to distribute their works without giving away
+the source code, and most solutions trade disk space for convenience.
+You probably won't see much of a speed increase either, since most
+solutions simply bundle a Perl interpreter in the final product
+(but see "How can I make my Perl program run faster?").
+.PP
+The Perl Archive Toolkit is Perl's analog to Java's JAR. It's freely
+available and on CPAN ( <https://metacpan.org/pod/PAR> ).
+.PP
+There are also some commercial products that may work for you, although
+you have to buy a license for them.
+.PP
+The Perl Dev Kit ( <http://www.activestate.com/Products/Perl_Dev_Kit/> )
+from ActiveState can "Turn your Perl programs into ready-to-run
+executables for HP-UX, Linux, Solaris and Windows."
+.PP
+Perl2Exe ( <http://www.indigostar.com/perl2exe.htm> ) is a command line
+program for converting perl scripts to executable files. It targets both
+Windows and Unix platforms.
+.ie n .SS "How can I get ""#!perl"" to work on [MS\-DOS,NT,...]?"
+.el .SS "How can I get \f(CW#!perl\fP to work on [MS\-DOS,NT,...]?"
+.IX Subsection "How can I get #!perl to work on [MS-DOS,NT,...]?"
+For OS/2 just use
+.PP
+.Vb 1
+\&    extproc perl \-S \-your_switches
+.Ve
+.PP
+as the first line in \f(CW\*(C`*.cmd\*(C'\fR file (\f(CW\*(C`\-S\*(C'\fR due to a bug in cmd.exe's
+"extproc" handling). For DOS one should first invent a corresponding
+batch file and codify it in \f(CW\*(C`ALTERNATE_SHEBANG\*(C'\fR (see the
+\&\fIdosish.h\fR file in the source distribution for more information).
+.PP
+The Win95/NT installation, when using the ActiveState port of Perl,
+will modify the Registry to associate the \f(CW\*(C`.pl\*(C'\fR extension with the
+perl interpreter. If you install another port, perhaps even building
+your own Win95/NT Perl from the standard sources by using a Windows port
+of gcc (e.g., with cygwin or mingw32), then you'll have to modify
+the Registry yourself. In addition to associating \f(CW\*(C`.pl\*(C'\fR with the
+interpreter, NT people can use: \f(CW\*(C`SET PATHEXT=%PATHEXT%;.PL\*(C'\fR to let them
+run the program \f(CW\*(C`install\-linux.pl\*(C'\fR merely by typing \f(CW\*(C`install\-linux\*(C'\fR.
+.PP
+Under "Classic" MacOS, a perl program will have the appropriate Creator and
+Type, so that double-clicking them will invoke the MacPerl application.
+Under Mac OS X, clickable apps can be made from any \f(CW\*(C`#!\*(C'\fR script using Wil
+Sanchez' DropScript utility: <http://www.wsanchez.net/software/> .
+.PP
+\&\fIIMPORTANT!\fR: Whatever you do, PLEASE don't get frustrated, and just
+throw the perl interpreter into your cgi-bin directory, in order to
+get your programs working for a web server. This is an EXTREMELY big
+security risk. Take the time to figure out how to do it correctly.
+.SS "Can I write useful Perl programs on the command line?"
+.IX Subsection "Can I write useful Perl programs on the command line?"
+Yes. Read perlrun for more information. Some examples follow.
+(These assume standard Unix shell quoting rules.)
+.PP
+.Vb 2
+\&    # sum first and last fields
+\&    perl \-lane \*(Aqprint $F[0] + $F[\-1]\*(Aq *
+\&
+\&    # identify text files
+\&    perl \-le \*(Aqfor(@ARGV) {print if \-f && \-T _}\*(Aq *
+\&
+\&    # remove (most) comments from C program
+\&    perl \-0777 \-pe \*(Aqs{/\e*.*?\e*/}{}gs\*(Aq foo.c
+\&
+\&    # make file a month younger than today, defeating reaper daemons
+\&    perl \-e \*(Aq$X=24*60*60; utime(time(),time() + 30 * $X,@ARGV)\*(Aq *
+\&
+\&    # find first unused uid
+\&    perl \-le \*(Aq$i++ while getpwuid($i); print $i\*(Aq
+\&
+\&    # display reasonable manpath
+\&    echo $PATH | perl \-nl \-072 \-e \*(Aq
+\&    s![^/+]*$!man!&&\-d&&!$s{$_}++&&push@m,$_;END{print"@m"}\*(Aq
+.Ve
+.PP
+OK, the last one was actually an Obfuscated Perl Contest entry. :\-)
+.SS "Why don't Perl one-liners work on my DOS/Mac/VMS system?"
+.IX Subsection "Why don't Perl one-liners work on my DOS/Mac/VMS system?"
+The problem is usually that the command interpreters on those systems
+have rather different ideas about quoting than the Unix shells under
+which the one-liners were created. On some systems, you may have to
+change single-quotes to double ones, which you must \fINOT\fR do on Unix
+or Plan9 systems. You might also have to change a single % to a %%.
+.PP
+For example:
+.PP
+.Vb 2
+\&    # Unix (including Mac OS X)
+\&    perl \-e \*(Aqprint "Hello world\en"\*(Aq
+\&
+\&    # DOS, etc.
+\&    perl \-e "print \e"Hello world\en\e""
+\&
+\&    # Mac Classic
+\&    print "Hello world\en"
+\&     (then Run "Myscript" or Shift\-Command\-R)
+\&
+\&    # MPW
+\&    perl \-e \*(Aqprint "Hello world\en"\*(Aq
+\&
+\&    # VMS
+\&    perl \-e "print ""Hello world\en"""
+.Ve
+.PP
+The problem is that none of these examples are reliable: they depend on the
+command interpreter. Under Unix, the first two often work. Under DOS,
+it's entirely possible that neither works. If 4DOS was the command shell,
+you'd probably have better luck like this:
+.PP
+.Vb 1
+\&  perl \-e "print <Ctrl\-x>"Hello world\en<Ctrl\-x>""
+.Ve
+.PP
+Under the Mac, it depends which environment you are using. The MacPerl
+shell, or MPW, is much like Unix shells in its support for several
+quoting variants, except that it makes free use of the Mac's non-ASCII
+characters as control characters.
+.PP
+Using \fBqq()\fR, q(), and \fBqx()\fR, instead of "double quotes", 'single
+quotes', and `backticks`, may make one-liners easier to write.
+.PP
+There is no general solution to all of this. It is a mess.
+.PP
+[Some of this answer was contributed by Kenneth Albanowski.]
+.SS "Where can I learn about CGI or Web programming in Perl?"
+.IX Subsection "Where can I learn about CGI or Web programming in Perl?"
+For modules, get the CGI or LWP modules from CPAN. For textbooks,
+see the two especially dedicated to web stuff in the question on
+books. For problems and questions related to the web, like "Why
+do I get 500 Errors" or "Why doesn't it run from the browser right
+when it runs fine on the command line", see the troubleshooting
+guides and references in perlfaq9 or in the CGI MetaFAQ:
+.PP
+.Vb 1
+\&    L<http://www.perl.org/CGI_MetaFAQ.html>
+.Ve
+.PP
+Looking into <https://plackperl.org> and modern Perl web frameworks is highly recommended,
+though; web programming in Perl has evolved a long way from the old days of
+simple CGI scripts.
+.SS "Where can I learn about object-oriented Perl programming?"
+.IX Subsection "Where can I learn about object-oriented Perl programming?"
+A good place to start is perlootut, and you can use perlobj for
+reference.
+.PP
+A good book on OO on Perl is the "Object-Oriented Perl"
+by Damian Conway from Manning Publications, or "Intermediate Perl"
+by Randal Schwartz, brian d foy, and Tom Phoenix from O'Reilly Media.
+.SS "Where can I learn about linking C with Perl?"
+.IX Subsection "Where can I learn about linking C with Perl?"
+If you want to call C from Perl, start with perlxstut,
+moving on to perlxs, xsubpp, and perlguts. If you want to
+call Perl from C, then read perlembed, perlcall, and
+perlguts. Don't forget that you can learn a lot from looking at
+how the authors of existing extension modules wrote their code and
+solved their problems.
+.PP
+You might not need all the power of XS. The Inline::C module lets
+you put C code directly in your Perl source. It handles all the
+magic to make it work. You still have to learn at least some of
+the perl API but you won't have to deal with the complexity of the
+XS support files.
+.SS "I've read perlembed, perlguts, etc., but I can't embed perl in my C program; what am I doing wrong?"
+.IX Subsection "I've read perlembed, perlguts, etc., but I can't embed perl in my C program; what am I doing wrong?"
+Download the ExtUtils::Embed kit from CPAN and run `make test'. If
+the tests pass, read the pods again and again and again. If they
+fail, submit a bug report to <https://github.com/Perl/perl5/issues>
+with the output of
+\&\f(CW\*(C`make test TEST_VERBOSE=1\*(C'\fR along with \f(CW\*(C`perl \-V\*(C'\fR.
+.SS "When I tried to run my script, I got this message. What does it mean?"
+.IX Subsection "When I tried to run my script, I got this message. What does it mean?"
+A complete list of Perl's error messages and warnings with explanatory
+text can be found in perldiag. You can also use the splain program
+(distributed with Perl) to explain the error messages:
+.PP
+.Vb 2
+\&    perl program 2>diag.out
+\&    splain [\-v] [\-p] diag.out
+.Ve
+.PP
+or change your program to explain the messages for you:
+.PP
+.Vb 1
+\&    use diagnostics;
+.Ve
+.PP
+or
+.PP
+.Vb 1
+\&    use diagnostics \-verbose;
+.Ve
+.SS "What's MakeMaker?"
+.IX Subsection "What's MakeMaker?"
+(contributed by brian d foy)
+.PP
+The ExtUtils::MakeMaker module, better known simply as "MakeMaker",
+turns a Perl script, typically called \f(CW\*(C`Makefile.PL\*(C'\fR, into a Makefile.
+The Unix tool \f(CW\*(C`make\*(C'\fR uses this file to manage dependencies and actions
+to process and install a Perl distribution.
+.SH "AUTHOR AND COPYRIGHT"
+.IX Header "AUTHOR AND COPYRIGHT"
+Copyright (c) 1997\-2010 Tom Christiansen, Nathan Torkington, and
+other authors as noted. All rights reserved.
+.PP
+This documentation is free; you can redistribute it and/or modify it
+under the same terms as Perl itself.
+.PP
+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.