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perlfaq3 - Programming Tools ($Revision: 1.38 $, $Date: 1999/05/23 16:08:30 $)
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This section of the FAQ answers questions related to programmer tools
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and programming support.
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=head2 How do I do (anything)?
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Have you looked at CPAN (see L<perlfaq2>)? The chances are that
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someone has already written a module that can solve your problem.
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Have you read the appropriate man pages? Here's a brief index:
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Basics perldata, perlvar, perlsyn, perlop, perlsub
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Execution perlrun, perldebug
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Objects perlref, perlmod, perlobj, perltie
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Data Structures perlref, perllol, perldsc
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Modules perlmod, perlmodlib, perlsub
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Regexes perlre, perlfunc, perlop, perllocale
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Moving to perl5 perltrap, perl
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Linking w/C perlxstut, perlxs, perlcall, perlguts, perlembed
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Various http://www.perl.com/CPAN/doc/FMTEYEWTK/index.html
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(not a man-page but still useful)
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A crude table of contents for the Perl man page set is found in L<perltoc>.
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=head2 How can I use Perl interactively?
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The typical approach uses the Perl debugger, described in the
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perldebug(1) man page, on an ``empty'' program, like this:
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Now just type in any legal Perl code, and it will be immediately
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evaluated. You can also examine the symbol table, get stack
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backtraces, check variable values, set breakpoints, and other
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operations typically found in symbolic debuggers.
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=head2 Is there a Perl shell?
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In general, no. The Shell.pm module (distributed with Perl) makes
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Perl try commands which aren't part of the Perl language as shell
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commands. perlsh from the source distribution is simplistic and
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uninteresting, but may still be what you want.
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=head2 How do I debug my Perl programs?
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Have you tried C<use warnings> or used C<-w>? They enable warnings
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to detect dubious practices.
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Have you tried C<use strict>? It prevents you from using symbolic
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references, makes you predeclare any subroutines that you call as bare
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words, and (probably most importantly) forces you to predeclare your
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variables with C<my>, C<our>, or C<use vars>.
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Did you check the return values of each and every system call? The operating
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system (and thus Perl) tells you whether they worked, and if not
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open(FH, "> /etc/cantwrite")
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or die "Couldn't write to /etc/cantwrite: $!\n";
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Did you read L<perltrap>? It's full of gotchas for old and new Perl
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programmers and even has sections for those of you who are upgrading
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from languages like I<awk> and I<C>.
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Have you tried the Perl debugger, described in L<perldebug>? You can
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step through your program and see what it's doing and thus work out
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why what it's doing isn't what it should be doing.
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=head2 How do I profile my Perl programs?
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You should get the Devel::DProf module from the standard distribution
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(or separately on CPAN) and also use Benchmark.pm from the standard
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distribution. The Benchmark module lets you time specific portions of
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your code, while Devel::DProf gives detailed breakdowns of where your
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Here's a sample use of Benchmark:
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@junk = `cat /etc/motd`;
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'map' => sub { my @a = @junk;
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'for' => sub { my @a = @junk;
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This is what it prints (on one machine--your results will be dependent
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on your hardware, operating system, and the load on your machine):
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Benchmark: timing 10000 iterations of for, map...
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for: 4 secs ( 3.97 usr 0.01 sys = 3.98 cpu)
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map: 6 secs ( 4.97 usr 0.00 sys = 4.97 cpu)
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Be aware that a good benchmark is very hard to write. It only tests the
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data you give it and proves little about the differing complexities
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of contrasting algorithms.
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=head2 How do I cross-reference my Perl programs?
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The B::Xref module, shipped with the new, alpha-release Perl compiler
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(not the general distribution prior to the 5.005 release), can be used
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to generate cross-reference reports for Perl programs.
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perl -MO=Xref[,OPTIONS] scriptname.plx
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=head2 Is there a pretty-printer (formatter) for Perl?
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There is no program that will reformat Perl as much as indent(1) does
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for C. The complex feedback between the scanner and the parser (this
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feedback is what confuses the vgrind and emacs programs) makes it
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challenging at best to write a stand-alone Perl parser.
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Of course, if you simply follow the guidelines in L<perlstyle>, you
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shouldn't need to reformat. The habit of formatting your code as you
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write it will help prevent bugs. Your editor can and should help you
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with this. The perl-mode or newer cperl-mode for emacs can provide
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remarkable amounts of help with most (but not all) code, and even less
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programmable editors can provide significant assistance. Tom swears
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by the following settings in vi and its clones:
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Now put that in your F<.exrc> file (replacing the caret characters
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with control characters) and away you go. In insert mode, ^T is
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for indenting, ^D is for undenting, and ^O is for blockdenting--
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as it were. If you haven't used the last one, you're missing
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a lot. A more complete example, with comments, can be found at
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http://www.perl.com/CPAN-local/authors/id/TOMC/scripts/toms.exrc.gz
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If you are used to using the I<vgrind> program for printing out nice code
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to a laser printer, you can take a stab at this using
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http://www.perl.com/CPAN/doc/misc/tips/working.vgrind.entry, but the
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results are not particularly satisfying for sophisticated code.
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The a2ps at http://www.infres.enst.fr/%7Edemaille/a2ps/ does lots of things
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related to generating nicely printed output of documents.
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=head2 Is there a ctags for Perl?
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There's a simple one at
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http://www.perl.com/CPAN/authors/id/TOMC/scripts/ptags.gz which may do
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the trick. And if not, it's easy to hack into what you want.
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=head2 Is there an IDE or Windows Perl Editor?
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Perl programs are just plain text, so any editor will do.
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If you're on Unix, you already have an IDE--Unix itself. The UNIX
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philosophy is the philosophy of several small tools that each do one
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thing and do it well. It's like a carpenter's toolbox.
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If you want a Windows IDE, check the following:
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http://www.codemagiccd.com/
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ActiveState's cross-platform, multi-language IDE has Perl support,
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including a regular expression debugger and remote debugging
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(http://www.ActiveState.com/Products/Komodo/index.html).
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(Visual Perl, a Visual Studio.NET plug-in is currently (early 2001)
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in beta (http://www.ActiveState.com/Products/VisualPerl/index.html)).
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=item The Object System
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(http://www.castlelink.co.uk/object_system/) is a Perl web
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applications development IDE.
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(http://www.solutionsoft.com/perl.htm) is an integrated development
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environment for Windows that supports Perl development.
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=item Perl code magic
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(http://www.petes-place.com/codemagic.html).
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http://helpconsulting.net/visiperl/, from Help Consulting.
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For editors: if you're on Unix you probably have vi or a vi clone already,
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and possibly an emacs too, so you may not need to download anything.
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In any emacs the cperl-mode (M-x cperl-mode) gives you perhaps the
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best available Perl editing mode in any editor.
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For Windows editors: you can download an Emacs
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http://www.gnu.org/software/emacs/windows/ntemacs.html
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http://members.nbci.com/uemacs/
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http://www.xemacs.org/Download/index.html
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or a vi clone such as
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ftp://ftp.cs.pdx.edu/pub/elvis/ http://www.fh-wedel.de/elvis/
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win32: http://www.cs.vu.nl/%7Etmgil/vi.html
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For vi lovers in general, Windows or elsewhere:
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http://www.thomer.com/thomer/vi/vi.html.
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nvi (http://www.bostic.com/vi/, available from CPAN in src/misc/) is
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yet another vi clone, unfortunately not available for Windows, but in
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UNIX platforms you might be interested in trying it out, firstly because
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strictly speaking it is not a vi clone, it is the real vi, or the new
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incarnation of it, and secondly because you can embed Perl inside it
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to use Perl as the scripting language. nvi is not alone in this,
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though: at least also vim and vile offer an embedded Perl.
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The following are Win32 multilanguage editor/IDESs that support Perl:
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http://www.starbase.com/
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http://www.MultiEdit.com/
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http://www.slickedit.com/
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There is also a toyedit Text widget based editor written in Perl
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that is distributed with the Tk module on CPAN. The ptkdb
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(http://world.std.com/~aep/ptkdb/) is a Perl/tk based debugger that
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acts as a development environment of sorts. Perl Composer
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(http://perlcomposer.sourceforge.net/vperl.html) is an IDE for Perl/Tk
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In addition to an editor/IDE you might be interested in a more
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powerful shell environment for Win32. Your options include
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from the Cygwin package (http://sources.redhat.com/cygwin/)
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from the MKS Toolkit (http://www.mks.com/), or the Bourne shell of
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the U/WIN environment (http://www.research.att.com/sw/tools/uwin/)
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ftp://ftp.astron.com/pub/tcsh/, see also
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http://www.primate.wisc.edu/software/csh-tcsh-book/
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ftp://ftp.blarg.net/users/amol/zsh/, see also http://www.zsh.org/
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MKS and U/WIN are commercial (U/WIN is free for educational and
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research purposes), Cygwin is covered by the GNU Public License (but
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that shouldn't matter for Perl use). The Cygwin, MKS, and U/WIN all
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contain (in addition to the shells) a comprehensive set of standard
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UNIX toolkit utilities.
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If you're transferring text files between Unix and Windows using FTP
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be sure to transfer them in ASCII mode so the ends of lines are
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appropriately converted.
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On Mac OS the MacPerl Application comes with a simple 32k text editor
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that behaves like a rudimentary IDE. In contrast to the MacPerl Application
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the MPW Perl tool can make use of the MPW Shell itself as an editor (with
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=item BBEdit and BBEdit Lite
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are text editors for Mac OS that have a Perl sensitivity mode
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(http://web.barebones.com/).
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is an editor, written and extensible in Tcl, that nonetheless has
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built in support for several popular markup and programming languages
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including Perl and HTML (http://alpha.olm.net/).
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Pepper and Pe are programming language sensitive text editors for Mac
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OS X and BeOS respectively (http://www.hekkelman.com/).
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=head2 Where can I get Perl macros for vi?
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For a complete version of Tom Christiansen's vi configuration file,
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see http://www.perl.com/CPAN/authors/Tom_Christiansen/scripts/toms.exrc.gz ,
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the standard benchmark file for vi emulators. The file runs best with nvi,
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the current version of vi out of Berkeley, which incidentally can be built
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with an embedded Perl interpreter--see http://www.perl.com/CPAN/src/misc.
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=head2 Where can I get perl-mode for emacs?
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Since Emacs version 19 patchlevel 22 or so, there have been both a
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perl-mode.el and support for the Perl debugger built in. These should
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come with the standard Emacs 19 distribution.
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In the Perl source directory, you'll find a directory called "emacs",
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which contains a cperl-mode that color-codes keywords, provides
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context-sensitive help, and other nifty things.
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Note that the perl-mode of emacs will have fits with C<"main'foo">
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(single quote), and mess up the indentation and highlighting. You
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are probably using C<"main::foo"> in new Perl code anyway, so this
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shouldn't be an issue.
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=head2 How can I use curses with Perl?
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The Curses module from CPAN provides a dynamically loadable object
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module interface to a curses library. A small demo can be found at the
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directory http://www.perl.com/CPAN/authors/Tom_Christiansen/scripts/rep;
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this program repeats a command and updates the screen as needed, rendering
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B<rep ps axu> similar to B<top>.
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=head2 How can I use X or Tk with Perl?
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Tk is a completely Perl-based, object-oriented interface to the Tk toolkit
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that doesn't force you to use Tcl just to get at Tk. Sx is an interface
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to the Athena Widget set. Both are available from CPAN. See the
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directory http://www.perl.com/CPAN/modules/by-category/08_User_Interfaces/
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Invaluable for Perl/Tk programming are the Perl/Tk FAQ at
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http://w4.lns.cornell.edu/%7Epvhp/ptk/ptkTOC.html , the Perl/Tk Reference
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http://www.perl.com/CPAN-local/authors/Stephen_O_Lidie/ , and the
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http://www-users.cs.umn.edu/%7Eamundson/perl/perltk/toc.html .
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=head2 How can I generate simple menus without using CGI or Tk?
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The http://www.perl.com/CPAN/authors/id/SKUNZ/perlmenu.v4.0.tar.gz
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module, which is curses-based, can help with this.
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=head2 What is undump?
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See the next question on ``How can I make my Perl program run faster?''
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=head2 How can I make my Perl program run faster?
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The best way to do this is to come up with a better algorithm. This
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can often make a dramatic difference. Jon Bentley's book
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``Programming Pearls'' (that's not a misspelling!) has some good tips
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on optimization, too. Advice on benchmarking boils down to: benchmark
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and profile to make sure you're optimizing the right part, look for
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better algorithms instead of microtuning your code, and when all else
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fails consider just buying faster hardware.
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A different approach is to autoload seldom-used Perl code. See the
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AutoSplit and AutoLoader modules in the standard distribution for
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that. Or you could locate the bottleneck and think about writing just
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that part in C, the way we used to take bottlenecks in C code and
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write them in assembler. Similar to rewriting in C,
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modules that have critical sections can be written in C (for instance, the
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PDL module from CPAN).
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In some cases, it may be worth it to use the backend compiler to
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produce byte code (saving compilation time) or compile into C, which
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will certainly save compilation time and sometimes a small amount (but
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not much) execution time. See the question about compiling your Perl
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programs for more on the compiler--the wins aren't as obvious as you'd
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If you're currently linking your perl executable to a shared I<libc.so>,
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you can often gain a 10-25% performance benefit by rebuilding it to
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link with a static libc.a instead. This will make a bigger perl
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executable, but your Perl programs (and programmers) may thank you for
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it. See the F<INSTALL> file in the source distribution for more
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Unsubstantiated reports allege that Perl interpreters that use sfio
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outperform those that don't (for I/O intensive applications). To try
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this, see the F<INSTALL> file in the source distribution, especially
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the ``Selecting File I/O mechanisms'' section.
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The undump program was an old attempt to speed up your Perl program
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by storing the already-compiled form to disk. This is no longer
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a viable option, as it only worked on a few architectures, and
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wasn't a good solution anyway.
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=head2 How can I make my Perl program take less memory?
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When it comes to time-space tradeoffs, Perl nearly always prefers to
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throw memory at a problem. Scalars in Perl use more memory than
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strings in C, arrays take more than that, and hashes use even more. While
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there's still a lot to be done, recent releases have been addressing
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these issues. For example, as of 5.004, duplicate hash keys are
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shared amongst all hashes using them, so require no reallocation.
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In some cases, using substr() or vec() to simulate arrays can be
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highly beneficial. For example, an array of a thousand booleans will
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take at least 20,000 bytes of space, but it can be turned into one
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125-byte bit vector--a considerable memory savings. The standard
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Tie::SubstrHash module can also help for certain types of data
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structure. If you're working with specialist data structures
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(matrices, for instance) modules that implement these in C may use
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less memory than equivalent Perl modules.
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Another thing to try is learning whether your Perl was compiled with
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the system malloc or with Perl's builtin malloc. Whichever one it
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is, try using the other one and see whether this makes a difference.
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Information about malloc is in the F<INSTALL> file in the source
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distribution. You can find out whether you are using perl's malloc by
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typing C<perl -V:usemymalloc>.
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=head2 Is it unsafe to return a pointer to local data?
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No, Perl's garbage collection system takes care of this.
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push @many, makeone();
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print $many[4][5], "\n";
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=head2 How can I free an array or hash so my program shrinks?
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You can't. On most operating systems, memory allocated to a program
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can never be returned to the system. That's why long-running programs
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sometimes re-exec themselves. Some operating systems (notably,
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FreeBSD and Linux) allegedly reclaim large chunks of memory that is no
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longer used, but it doesn't appear to happen with Perl (yet). The Mac
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appears to be the only platform that will reliably (albeit, slowly)
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return memory to the OS.
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We've had reports that on Linux (Redhat 5.1) on Intel, C<undef
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$scalar> will return memory to the system, while on Solaris 2.6 it
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won't. In general, try it yourself and see.
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However, judicious use of my() on your variables will help make sure
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that they go out of scope so that Perl can free up that space for
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use in other parts of your program. A global variable, of course, never
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goes out of scope, so you can't get its space automatically reclaimed,
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although undef()ing and/or delete()ing it will achieve the same effect.
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In general, memory allocation and de-allocation isn't something you can
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or should be worrying about much in Perl, but even this capability
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(preallocation of data types) is in the works.
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=head2 How can I make my CGI script more efficient?
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Beyond the normal measures described to make general Perl programs
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faster or smaller, a CGI program has additional issues. It may be run
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several times per second. Given that each time it runs it will need
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to be re-compiled and will often allocate a megabyte or more of system
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memory, this can be a killer. Compiling into C B<isn't going to help
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you> because the process start-up overhead is where the bottleneck is.
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There are two popular ways to avoid this overhead. One solution
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involves running the Apache HTTP server (available from
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http://www.apache.org/) with either of the mod_perl or mod_fastcgi
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With mod_perl and the Apache::Registry module (distributed with
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mod_perl), httpd will run with an embedded Perl interpreter which
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pre-compiles your script and then executes it within the same address
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space without forking. The Apache extension also gives Perl access to
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the internal server API, so modules written in Perl can do just about
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anything a module written in C can. For more on mod_perl, see
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http://perl.apache.org/
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With the FCGI module (from CPAN) and the mod_fastcgi
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module (available from http://www.fastcgi.com/) each of your Perl
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programs becomes a permanent CGI daemon process.
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Both of these solutions can have far-reaching effects on your system
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and on the way you write your CGI programs, so investigate them with
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See http://www.perl.com/CPAN/modules/by-category/15_World_Wide_Web_HTML_HTTP_CGI/ .
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A non-free, commercial product, ``The Velocity Engine for Perl'',
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(http://www.binevolve.com/ or http://www.binevolve.com/velocigen/ )
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might also be worth looking at. It will allow you to increase the
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performance of your Perl programs, running programs up to 25 times
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faster than normal CGI Perl when running in persistent Perl mode or 4
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to 5 times faster without any modification to your existing CGI
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programs. Fully functional evaluation copies are available from the
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=head2 How can I hide the source for my Perl program?
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Delete it. :-) Seriously, there are a number of (mostly
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unsatisfactory) solutions with varying levels of ``security''.
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First of all, however, you I<can't> take away read permission, because
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the source code has to be readable in order to be compiled and
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interpreted. (That doesn't mean that a CGI script's source is
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readable by people on the web, though--only by people with access to
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the filesystem.) So you have to leave the permissions at the socially
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Some people regard this as a security problem. If your program does
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insecure things and relies on people not knowing how to exploit those
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insecurities, it is not secure. It is often possible for someone to
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determine the insecure things and exploit them without viewing the
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source. Security through obscurity, the name for hiding your bugs
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instead of fixing them, is little security indeed.
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You can try using encryption via source filters (Filter::* from CPAN),
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but any decent programmer will be able to decrypt it. You can try using
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the byte code compiler and interpreter described below, but the curious
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might still be able to de-compile it. You can try using the native-code
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compiler described below, but crackers might be able to disassemble it.
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These pose varying degrees of difficulty to people wanting to get at
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your code, but none can definitively conceal it (true of every
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language, not just Perl).
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If you're concerned about people profiting from your code, then the
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bottom line is that nothing but a restrictive license will give you
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legal security. License your software and pepper it with threatening
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statements like ``This is unpublished proprietary software of XYZ Corp.
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Your access to it does not give you permission to use it blah blah
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blah.'' We are not lawyers, of course, so you should see a lawyer if
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you want to be sure your license's wording will stand up in court.
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=head2 How can I compile my Perl program into byte code or C?
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Malcolm Beattie has written a multifunction backend compiler,
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available from CPAN, that can do both these things. It is included
581
in the perl5.005 release, but is still considered experimental.
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This means it's fun to play with if you're a programmer but not
583
really for people looking for turn-key solutions.
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Merely compiling into C does not in and of itself guarantee that your
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code will run very much faster. That's because except for lucky cases
587
where a lot of native type inferencing is possible, the normal Perl
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run-time system is still present and so your program will take just as
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long to run and be just as big. Most programs save little more than
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compilation time, leaving execution no more than 10-30% faster. A few
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rare programs actually benefit significantly (even running several times
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faster), but this takes some tweaking of your code.
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You'll probably be astonished to learn that the current version of the
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compiler generates a compiled form of your script whose executable is
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just as big as the original perl executable, and then some. That's
597
because as currently written, all programs are prepared for a full
598
eval() statement. You can tremendously reduce this cost by building a
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shared I<libperl.so> library and linking against that. See the
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F<INSTALL> podfile in the Perl source distribution for details. If
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you link your main perl binary with this, it will make it minuscule.
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For example, on one author's system, F</usr/bin/perl> is only 11k in
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In general, the compiler will do nothing to make a Perl program smaller,
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faster, more portable, or more secure. In fact, it can make your
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situation worse. The executable will be bigger, your VM system may take
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longer to load the whole thing, the binary is fragile and hard to fix,
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and compilation never stopped software piracy in the form of crackers,
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viruses, or bootleggers. The real advantage of the compiler is merely
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packaging, and once you see the size of what it makes (well, unless
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you use a shared I<libperl.so>), you'll probably want a complete
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=head2 How can I compile Perl into Java?
617
You can also integrate Java and Perl with the
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Perl Resource Kit from O'Reilly and Associates. See
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http://www.oreilly.com/catalog/prkunix/ .
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Perl 5.6 comes with Java Perl Lingo, or JPL. JPL, still in
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development, allows Perl code to be called from Java. See jpl/README
623
in the Perl source tree.
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=head2 How can I get C<#!perl> to work on [MS-DOS,NT,...]?
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extproc perl -S -your_switches
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as the first line in C<*.cmd> file (C<-S> due to a bug in cmd.exe's
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`extproc' handling). For DOS one should first invent a corresponding
633
batch file and codify it in C<ALTERNATIVE_SHEBANG> (see the
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F<INSTALL> file in the source distribution for more information).
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The Win95/NT installation, when using the ActiveState port of Perl,
637
will modify the Registry to associate the C<.pl> extension with the
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perl interpreter. If you install another port, perhaps even building
639
your own Win95/NT Perl from the standard sources by using a Windows port
640
of gcc (e.g., with cygwin or mingw32), then you'll have to modify
641
the Registry yourself. In addition to associating C<.pl> with the
642
interpreter, NT people can use: C<SET PATHEXT=%PATHEXT%;.PL> to let them
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run the program C<install-linux.pl> merely by typing C<install-linux>.
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Macintosh Perl programs will have the appropriate Creator and
646
Type, so that double-clicking them will invoke the Perl application.
648
I<IMPORTANT!>: Whatever you do, PLEASE don't get frustrated, and just
649
throw the perl interpreter into your cgi-bin directory, in order to
650
get your programs working for a web server. This is an EXTREMELY big
651
security risk. Take the time to figure out how to do it correctly.
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=head2 Can I write useful Perl programs on the command line?
655
Yes. Read L<perlrun> for more information. Some examples follow.
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(These assume standard Unix shell quoting rules.)
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# sum first and last fields
659
perl -lane 'print $F[0] + $F[-1]' *
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# identify text files
662
perl -le 'for(@ARGV) {print if -f && -T _}' *
664
# remove (most) comments from C program
665
perl -0777 -pe 's{/\*.*?\*/}{}gs' foo.c
667
# make file a month younger than today, defeating reaper daemons
668
perl -e '$X=24*60*60; utime(time(),time() + 30 * $X,@ARGV)' *
670
# find first unused uid
671
perl -le '$i++ while getpwuid($i); print $i'
673
# display reasonable manpath
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echo $PATH | perl -nl -072 -e '
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s![^/+]*$!man!&&-d&&!$s{$_}++&&push@m,$_;END{print"@m"}'
677
OK, the last one was actually an Obfuscated Perl Contest entry. :-)
679
=head2 Why don't Perl one-liners work on my DOS/Mac/VMS system?
681
The problem is usually that the command interpreters on those systems
682
have rather different ideas about quoting than the Unix shells under
683
which the one-liners were created. On some systems, you may have to
684
change single-quotes to double ones, which you must I<NOT> do on Unix
685
or Plan9 systems. You might also have to change a single % to a %%.
690
perl -e 'print "Hello world\n"'
693
perl -e "print \"Hello world\n\""
696
print "Hello world\n"
697
(then Run "Myscript" or Shift-Command-R)
700
perl -e "print ""Hello world\n"""
702
The problem is that none of these examples are reliable: they depend on the
703
command interpreter. Under Unix, the first two often work. Under DOS,
704
it's entirely possible that neither works. If 4DOS was the command shell,
705
you'd probably have better luck like this:
707
perl -e "print <Ctrl-x>"Hello world\n<Ctrl-x>""
709
Under the Mac, it depends which environment you are using. The MacPerl
710
shell, or MPW, is much like Unix shells in its support for several
711
quoting variants, except that it makes free use of the Mac's non-ASCII
712
characters as control characters.
714
Using qq(), q(), and qx(), instead of "double quotes", 'single
715
quotes', and `backticks`, may make one-liners easier to write.
717
There is no general solution to all of this. It is a mess, pure and
718
simple. Sucks to be away from Unix, huh? :-)
720
[Some of this answer was contributed by Kenneth Albanowski.]
722
=head2 Where can I learn about CGI or Web programming in Perl?
724
For modules, get the CGI or LWP modules from CPAN. For textbooks,
725
see the two especially dedicated to web stuff in the question on
726
books. For problems and questions related to the web, like ``Why
727
do I get 500 Errors'' or ``Why doesn't it run from the browser right
728
when it runs fine on the command line'', see these sources:
731
http://www.w3.org/Security/Faq/
734
http://www.boutell.com/faq/
737
http://www.webthing.com/tutorials/cgifaq.html
740
http://www.w3.org/pub/WWW/Protocols/HTTP/
743
http://www.w3.org/TR/REC-html40/
744
http://www.w3.org/pub/WWW/MarkUp/
747
http://www.w3.org/CGI/
750
http://www.go2net.com/people/paulp/cgi-security/safe-cgi.txt
752
=head2 Where can I learn about object-oriented Perl programming?
754
A good place to start is L<perltoot>, and you can use L<perlobj>,
755
L<perlboot>, and L<perlbot> for reference. Perltoot didn't come out
756
until the 5.004 release; you can get a copy (in pod, html, or
757
postscript) from http://www.perl.com/CPAN/doc/FMTEYEWTK/ .
759
=head2 Where can I learn about linking C with Perl? [h2xs, xsubpp]
761
If you want to call C from Perl, start with L<perlxstut>,
762
moving on to L<perlxs>, L<xsubpp>, and L<perlguts>. If you want to
763
call Perl from C, then read L<perlembed>, L<perlcall>, and
764
L<perlguts>. Don't forget that you can learn a lot from looking at
765
how the authors of existing extension modules wrote their code and
766
solved their problems.
768
=head2 I've read perlembed, perlguts, etc., but I can't embed perl in
769
my C program; what am I doing wrong?
771
Download the ExtUtils::Embed kit from CPAN and run `make test'. If
772
the tests pass, read the pods again and again and again. If they
773
fail, see L<perlbug> and send a bug report with the output of
774
C<make test TEST_VERBOSE=1> along with C<perl -V>.
776
=head2 When I tried to run my script, I got this message. What does it
779
A complete list of Perl's error messages and warnings with explanatory
780
text can be found in L<perldiag>. You can also use the splain program
781
(distributed with Perl) to explain the error messages:
783
perl program 2>diag.out
784
splain [-v] [-p] diag.out
786
or change your program to explain the messages for you:
792
use diagnostics -verbose;
794
=head2 What's MakeMaker?
796
This module (part of the standard Perl distribution) is designed to
797
write a Makefile for an extension module from a Makefile.PL. For more
798
information, see L<ExtUtils::MakeMaker>.
800
=head1 AUTHOR AND COPYRIGHT
802
Copyright (c) 1997-1999 Tom Christiansen and Nathan Torkington.
805
When included as an integrated part of the Standard Distribution
806
of Perl or of its documentation (printed or otherwise), this works is
807
covered under Perl's Artistic License. For separate distributions of
808
all or part of this FAQ outside of that, see L<perlfaq>.
810
Irrespective of its distribution, all code examples here are in the public
811
domain. You are permitted and encouraged to use this code and any
812
derivatives thereof in your own programs for fun or for profit as you
813
see fit. A simple comment in the code giving credit to the FAQ would
814
be courteous but is not required.
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0CPAN/Pod-Simple-3.03/t/test_old_perlfaq3.pod
