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68dc0745 | 1 | =head1 NAME |
2 | ||
c195e131 | 3 | perlfaq3 - Programming Tools ($Revision: 10127 $) |
68dc0745 | 4 | |
5 | =head1 DESCRIPTION | |
6 | ||
7 | This section of the FAQ answers questions related to programmer tools | |
8 | and programming support. | |
9 | ||
10 | =head2 How do I do (anything)? | |
11 | ||
12 | Have you looked at CPAN (see L<perlfaq2>)? The chances are that | |
13 | someone has already written a module that can solve your problem. | |
3958b146 | 14 | Have you read the appropriate manpages? Here's a brief index: |
68dc0745 | 15 | |
5a964f20 TC |
16 | Basics perldata, perlvar, perlsyn, perlop, perlsub |
17 | Execution perlrun, perldebug | |
18 | Functions perlfunc | |
68dc0745 | 19 | Objects perlref, perlmod, perlobj, perltie |
20 | Data Structures perlref, perllol, perldsc | |
f102b883 | 21 | Modules perlmod, perlmodlib, perlsub |
d92eb7b0 | 22 | Regexes perlre, perlfunc, perlop, perllocale |
68dc0745 | 23 | Moving to perl5 perltrap, perl |
24 | Linking w/C perlxstut, perlxs, perlcall, perlguts, perlembed | |
06a5f41f JH |
25 | Various http://www.cpan.org/misc/olddoc/FMTEYEWTK.tgz |
26 | (not a man-page but still useful, a collection | |
27 | of various essays on Perl techniques) | |
68dc0745 | 28 | |
3958b146 | 29 | A crude table of contents for the Perl manpage set is found in L<perltoc>. |
68dc0745 | 30 | |
31 | =head2 How can I use Perl interactively? | |
32 | ||
33 | The typical approach uses the Perl debugger, described in the | |
b432a672 | 34 | perldebug(1) manpage, on an "empty" program, like this: |
68dc0745 | 35 | |
36 | perl -de 42 | |
37 | ||
38 | Now just type in any legal Perl code, and it will be immediately | |
39 | evaluated. You can also examine the symbol table, get stack | |
40 | backtraces, check variable values, set breakpoints, and other | |
92c2ed05 | 41 | operations typically found in symbolic debuggers. |
68dc0745 | 42 | |
43 | =head2 Is there a Perl shell? | |
44 | ||
a05e4845 RGS |
45 | The psh (Perl sh) is currently at version 1.8. The Perl Shell is a shell |
46 | that combines the interactive nature of a Unix shell with the power of | |
47 | Perl. The goal is a full featured shell that behaves as expected for | |
48 | normal shell activity and uses Perl syntax and functionality for | |
49 | control-flow statements and other things. You can get psh at | |
50 | http://sourceforge.net/projects/psh/ . | |
55e174a4 | 51 | |
f3b9614f RGS |
52 | Zoidberg is a similar project and provides a shell written in perl, |
53 | configured in perl and operated in perl. It is intended as a login shell | |
54 | and development environment. It can be found at http://zoidberg.sf.net/ | |
55 | or your local CPAN mirror. | |
56 | ||
55e174a4 | 57 | The Shell.pm module (distributed with Perl) makes Perl try commands |
a05e4845 RGS |
58 | which aren't part of the Perl language as shell commands. perlsh from |
59 | the source distribution is simplistic and uninteresting, but may still | |
60 | be what you want. | |
68dc0745 | 61 | |
49d635f9 RGS |
62 | =head2 How do I find which modules are installed on my system? |
63 | ||
a05e4845 RGS |
64 | You can use the ExtUtils::Installed module to show all installed |
65 | distributions, although it can take awhile to do its magic. The | |
66 | standard library which comes with Perl just shows up as "Perl" (although | |
67 | you can get those with Module::CoreList). | |
49d635f9 RGS |
68 | |
69 | use ExtUtils::Installed; | |
197aec24 | 70 | |
49d635f9 RGS |
71 | my $inst = ExtUtils::Installed->new(); |
72 | my @modules = $inst->modules(); | |
73 | ||
74 | If you want a list of all of the Perl module filenames, you | |
75 | can use File::Find::Rule. | |
76 | ||
77 | use File::Find::Rule; | |
197aec24 | 78 | |
49d635f9 RGS |
79 | my @files = File::Find::Rule->file()->name( '*.pm' )->in( @INC ); |
80 | ||
81 | If you do not have that module, you can do the same thing | |
197aec24 | 82 | with File::Find which is part of the standard library. |
49d635f9 RGS |
83 | |
84 | use File::Find; | |
85 | my @files; | |
86 | ||
54bd407c | 87 | find( |
58103a2e RGS |
88 | sub { |
89 | push @files, $File::Find::name | |
90 | if -f $File::Find::name && /\.pm$/ | |
a05e4845 | 91 | }, |
58103a2e | 92 | |
54bd407c | 93 | @INC |
a05e4845 | 94 | ); |
49d635f9 | 95 | |
a05e4845 | 96 | print join "\n", @files; |
197aec24 | 97 | |
49d635f9 RGS |
98 | If you simply need to quickly check to see if a module is |
99 | available, you can check for its documentation. If you can | |
197aec24 | 100 | read the documentation the module is most likely installed. |
49d635f9 RGS |
101 | If you cannot read the documentation, the module might not |
102 | have any (in rare cases). | |
103 | ||
104 | prompt% perldoc Module::Name | |
105 | ||
106 | You can also try to include the module in a one-liner to see if | |
107 | perl finds it. | |
108 | ||
109 | perl -MModule::Name -e1 | |
197aec24 | 110 | |
68dc0745 | 111 | =head2 How do I debug my Perl programs? |
112 | ||
500071f4 RGS |
113 | (contributed by brian d foy) |
114 | ||
115 | Before you do anything else, you can help yourself by ensuring that | |
116 | you let Perl tell you about problem areas in your code. By turning | |
ac9dac7f | 117 | on warnings and strictures, you can head off many problems before |
500071f4 RGS |
118 | they get too big. You can find out more about these in L<strict> |
119 | and L<warnings>. | |
120 | ||
121 | #!/usr/bin/perl | |
122 | use strict; | |
123 | use warnings; | |
ac9dac7f | 124 | |
500071f4 RGS |
125 | Beyond that, the simplest debugger is the C<print> function. Use it |
126 | to look at values as you run your program: | |
127 | ||
128 | print STDERR "The value is [$value]\n"; | |
68dc0745 | 129 | |
500071f4 | 130 | The C<Data::Dumper> module can pretty-print Perl data structures: |
68dc0745 | 131 | |
ac9dac7f RGS |
132 | use Data::Dumper qw( Dumper ); |
133 | print STDERR "The hash is " . Dumper( \%hash ) . "\n"; | |
134 | ||
500071f4 RGS |
135 | Perl comes with an interactive debugger, which you can start with the |
136 | C<-d> switch. It's fully explained in L<perldebug>. | |
68dc0745 | 137 | |
500071f4 RGS |
138 | If you'd like a graphical user interface and you have Tk, you can use |
139 | C<ptkdb>. It's on CPAN and available for free. | |
68dc0745 | 140 | |
c195e131 | 141 | If you need something much more sophisticated and controllable, Leon |
500071f4 RGS |
142 | Brocard's Devel::ebug (which you can call with the -D switch as -Debug) |
143 | gives you the programmatic hooks into everything you need to write your | |
144 | own (without too much pain and suffering). | |
92c2ed05 | 145 | |
500071f4 RGS |
146 | You can also use a commercial debugger such as Affrus (Mac OS X), Komodo |
147 | from Activestate (Windows and Mac OS X), or EPIC (most platforms). | |
68dc0745 | 148 | |
149 | =head2 How do I profile my Perl programs? | |
150 | ||
e083a89c | 151 | You should get the Devel::DProf module from the standard distribution |
197aec24 RGS |
152 | (or separately on CPAN) and also use Benchmark.pm from the standard |
153 | distribution. The Benchmark module lets you time specific portions of | |
154 | your code, while Devel::DProf gives detailed breakdowns of where your | |
e083a89c | 155 | code spends its time. |
68dc0745 | 156 | |
92c2ed05 GS |
157 | Here's a sample use of Benchmark: |
158 | ||
159 | use Benchmark; | |
160 | ||
161 | @junk = `cat /etc/motd`; | |
162 | $count = 10_000; | |
163 | ||
164 | timethese($count, { | |
165 | 'map' => sub { my @a = @junk; | |
166 | map { s/a/b/ } @a; | |
6c43ef16 | 167 | return @a }, |
92c2ed05 | 168 | 'for' => sub { my @a = @junk; |
92c2ed05 GS |
169 | for (@a) { s/a/b/ }; |
170 | return @a }, | |
171 | }); | |
172 | ||
173 | This is what it prints (on one machine--your results will be dependent | |
174 | on your hardware, operating system, and the load on your machine): | |
175 | ||
176 | Benchmark: timing 10000 iterations of for, map... | |
177 | for: 4 secs ( 3.97 usr 0.01 sys = 3.98 cpu) | |
178 | map: 6 secs ( 4.97 usr 0.00 sys = 4.97 cpu) | |
179 | ||
65acb1b1 | 180 | Be aware that a good benchmark is very hard to write. It only tests the |
a6dd486b | 181 | data you give it and proves little about the differing complexities |
65acb1b1 TC |
182 | of contrasting algorithms. |
183 | ||
68dc0745 | 184 | =head2 How do I cross-reference my Perl programs? |
185 | ||
197aec24 | 186 | The B::Xref module can be used to generate cross-reference reports |
83ded9ee | 187 | for Perl programs. |
68dc0745 | 188 | |
c8db1d39 | 189 | perl -MO=Xref[,OPTIONS] scriptname.plx |
68dc0745 | 190 | |
191 | =head2 Is there a pretty-printer (formatter) for Perl? | |
192 | ||
55e174a4 JH |
193 | Perltidy is a Perl script which indents and reformats Perl scripts |
194 | to make them easier to read by trying to follow the rules of the | |
195 | L<perlstyle>. If you write Perl scripts, or spend much time reading | |
196 | them, you will probably find it useful. It is available at | |
197 | http://perltidy.sourceforge.net | |
198 | ||
199 | Of course, if you simply follow the guidelines in L<perlstyle>, | |
200 | you shouldn't need to reformat. The habit of formatting your code | |
201 | as you write it will help prevent bugs. Your editor can and should | |
202 | help you with this. The perl-mode or newer cperl-mode for emacs | |
203 | can provide remarkable amounts of help with most (but not all) | |
204 | code, and even less programmable editors can provide significant | |
205 | assistance. Tom Christiansen and many other VI users swear by | |
206 | the following settings in vi and its clones: | |
65acb1b1 TC |
207 | |
208 | set ai sw=4 | |
d92eb7b0 | 209 | map! ^O {^M}^[O^T |
65acb1b1 | 210 | |
55e174a4 | 211 | Put that in your F<.exrc> file (replacing the caret characters |
65acb1b1 | 212 | with control characters) and away you go. In insert mode, ^T is |
ac9dac7f RGS |
213 | for indenting, ^D is for undenting, and ^O is for blockdenting--as |
214 | it were. A more complete example, with comments, can be found at | |
213329dd | 215 | http://www.cpan.org/authors/id/TOMC/scripts/toms.exrc.gz |
92c2ed05 | 216 | |
49d635f9 | 217 | The a2ps http://www-inf.enst.fr/%7Edemaille/a2ps/black+white.ps.gz does |
06a5f41f | 218 | lots of things related to generating nicely printed output of |
c195e131 | 219 | documents. |
65acb1b1 | 220 | |
d92eb7b0 | 221 | =head2 Is there a ctags for Perl? |
68dc0745 | 222 | |
b68463f7 RGS |
223 | (contributed by brian d foy) |
224 | ||
ac9dac7f RGS |
225 | Ctags uses an index to quickly find things in source code, and many |
226 | popular editors support ctags for several different languages, | |
227 | including Perl. | |
228 | ||
b68463f7 | 229 | Exuberent ctags supports Perl: http://ctags.sourceforge.net/ |
bc06af74 | 230 | |
b68463f7 | 231 | You might also try pltags: http://www.mscha.com/pltags.zip |
65acb1b1 TC |
232 | |
233 | =head2 Is there an IDE or Windows Perl Editor? | |
234 | ||
6641ed39 JH |
235 | Perl programs are just plain text, so any editor will do. |
236 | ||
6641ed39 JH |
237 | If you're on Unix, you already have an IDE--Unix itself. The UNIX |
238 | philosophy is the philosophy of several small tools that each do one | |
239 | thing and do it well. It's like a carpenter's toolbox. | |
240 | ||
28b41a80 RGS |
241 | If you want an IDE, check the following (in alphabetical order, not |
242 | order of preference): | |
68fbfbd7 JH |
243 | |
244 | =over 4 | |
245 | ||
28b41a80 RGS |
246 | =item Eclipse |
247 | ||
b68463f7 RGS |
248 | http://e-p-i-c.sf.net/ |
249 | ||
6670e5e7 | 250 | The Eclipse Perl Integration Project integrates Perl |
28b41a80 RGS |
251 | editing/debugging with Eclipse. |
252 | ||
b68463f7 RGS |
253 | =item Enginsite |
254 | ||
255 | http://www.enginsite.com/ | |
256 | ||
257 | Perl Editor by EngInSite is a complete integrated development | |
258 | environment (IDE) for creating, testing, and debugging Perl scripts; | |
259 | the tool runs on Windows 9x/NT/2000/XP or later. | |
28b41a80 | 260 | |
68fbfbd7 JH |
261 | =item Komodo |
262 | ||
b68463f7 RGS |
263 | http://www.ActiveState.com/Products/Komodo/ |
264 | ||
28b41a80 RGS |
265 | ActiveState's cross-platform (as of October 2004, that's Windows, Linux, |
266 | and Solaris), multi-language IDE has Perl support, including a regular expression | |
b68463f7 | 267 | debugger and remote debugging. |
68fbfbd7 | 268 | |
ac1094a1 JH |
269 | =item Open Perl IDE |
270 | ||
b68463f7 RGS |
271 | http://open-perl-ide.sourceforge.net/ |
272 | ||
ac1094a1 JH |
273 | Open Perl IDE is an integrated development environment for writing |
274 | and debugging Perl scripts with ActiveState's ActivePerl distribution | |
275 | under Windows 95/98/NT/2000. | |
276 | ||
28b41a80 RGS |
277 | =item OptiPerl |
278 | ||
b68463f7 RGS |
279 | http://www.optiperl.com/ |
280 | ||
281 | OptiPerl is a Windows IDE with simulated CGI environment, including | |
282 | debugger and syntax highlighting editor. | |
28b41a80 | 283 | |
5ca69f12 JH |
284 | =item PerlBuilder |
285 | ||
b68463f7 RGS |
286 | http://www.solutionsoft.com/perl.htm |
287 | ||
288 | PerlBuidler is an integrated development environment for Windows that | |
289 | supports Perl development. | |
8782d048 | 290 | |
68fbfbd7 JH |
291 | =item visiPerl+ |
292 | ||
b68463f7 RGS |
293 | http://helpconsulting.net/visiperl/ |
294 | ||
ac1094a1 | 295 | From Help Consulting, for Windows. |
68fbfbd7 | 296 | |
28b41a80 RGS |
297 | =item Visual Perl |
298 | ||
b68463f7 RGS |
299 | http://www.activestate.com/Products/Visual_Perl/ |
300 | ||
28b41a80 | 301 | Visual Perl is a Visual Studio.NET plug-in from ActiveState. |
29b1171f | 302 | |
b68463f7 RGS |
303 | =item Zeus |
304 | ||
305 | http://www.zeusedit.com/lookmain.html | |
306 | ||
307 | Zeus for Window is another Win32 multi-language editor/IDE | |
308 | that comes with support for Perl: | |
29b1171f | 309 | |
68fbfbd7 JH |
310 | =back |
311 | ||
b68463f7 RGS |
312 | For editors: if you're on Unix you probably have vi or a vi clone |
313 | already, and possibly an emacs too, so you may not need to download | |
314 | anything. In any emacs the cperl-mode (M-x cperl-mode) gives you | |
315 | perhaps the best available Perl editing mode in any editor. | |
316 | ||
317 | If you are using Windows, you can use any editor that lets you work | |
318 | with plain text, such as NotePad or WordPad. Word processors, such as | |
319 | Microsoft Word or WordPerfect, typically do not work since they insert | |
320 | all sorts of behind-the-scenes information, although some allow you to | |
321 | save files as "Text Only". You can also download text editors designed | |
322 | specifically for programming, such as Textpad ( | |
323 | http://www.textpad.com/ ) and UltraEdit ( http://www.ultraedit.com/ ), | |
324 | among others. | |
325 | ||
326 | If you are using MacOS, the same concerns apply. MacPerl (for Classic | |
327 | environments) comes with a simple editor. Popular external editors are | |
328 | BBEdit ( http://www.bbedit.com/ ) or Alpha ( | |
329 | http://www.his.com/~jguyer/Alpha/Alpha8.html ). MacOS X users can use | |
c195e131 | 330 | Unix editors as well. |
68fbfbd7 JH |
331 | |
332 | =over 4 | |
333 | ||
334 | =item GNU Emacs | |
335 | ||
336 | http://www.gnu.org/software/emacs/windows/ntemacs.html | |
337 | ||
338 | =item MicroEMACS | |
339 | ||
49d635f9 | 340 | http://www.microemacs.de/ |
68fbfbd7 JH |
341 | |
342 | =item XEmacs | |
343 | ||
344 | http://www.xemacs.org/Download/index.html | |
345 | ||
49d635f9 RGS |
346 | =item Jed |
347 | ||
348 | http://space.mit.edu/~davis/jed/ | |
349 | ||
68fbfbd7 JH |
350 | =back |
351 | ||
352 | or a vi clone such as | |
353 | ||
354 | =over 4 | |
355 | ||
356 | =item Elvis | |
357 | ||
358 | ftp://ftp.cs.pdx.edu/pub/elvis/ http://www.fh-wedel.de/elvis/ | |
359 | ||
360 | =item Vile | |
361 | ||
49d635f9 | 362 | http://dickey.his.com/vile/vile.html |
68fbfbd7 JH |
363 | |
364 | =item Vim | |
365 | ||
366 | http://www.vim.org/ | |
367 | ||
68fbfbd7 JH |
368 | =back |
369 | ||
5a13f98a | 370 | For vi lovers in general, Windows or elsewhere: |
f05bbc40 JH |
371 | |
372 | http://www.thomer.com/thomer/vi/vi.html | |
6641ed39 | 373 | |
f224927c | 374 | nvi ( http://www.bostic.com/vi/ , available from CPAN in src/misc/) is |
5a13f98a | 375 | yet another vi clone, unfortunately not available for Windows, but in |
6641ed39 JH |
376 | UNIX platforms you might be interested in trying it out, firstly because |
377 | strictly speaking it is not a vi clone, it is the real vi, or the new | |
378 | incarnation of it, and secondly because you can embed Perl inside it | |
379 | to use Perl as the scripting language. nvi is not alone in this, | |
7c82de66 | 380 | though: at least also vim and vile offer an embedded Perl. |
614a1598 | 381 | |
68fbfbd7 JH |
382 | The following are Win32 multilanguage editor/IDESs that support Perl: |
383 | ||
384 | =over 4 | |
385 | ||
386 | =item Codewright | |
387 | ||
c98c5709 | 388 | http://www.borland.com/codewright/ |
68fbfbd7 JH |
389 | |
390 | =item MultiEdit | |
391 | ||
392 | http://www.MultiEdit.com/ | |
393 | ||
394 | =item SlickEdit | |
395 | ||
396 | http://www.slickedit.com/ | |
397 | ||
398 | =back | |
8782d048 | 399 | |
6641ed39 JH |
400 | There is also a toyedit Text widget based editor written in Perl |
401 | that is distributed with the Tk module on CPAN. The ptkdb | |
c195e131 | 402 | ( http://ptkdb.sourceforge.net/ ) is a Perl/tk based debugger that |
8782d048 | 403 | acts as a development environment of sorts. Perl Composer |
49d635f9 | 404 | ( http://perlcomposer.sourceforge.net/ ) is an IDE for Perl/Tk |
e083a89c JH |
405 | GUI creation. |
406 | ||
8782d048 | 407 | In addition to an editor/IDE you might be interested in a more |
68fbfbd7 JH |
408 | powerful shell environment for Win32. Your options include |
409 | ||
410 | =over 4 | |
411 | ||
412 | =item Bash | |
413 | ||
1577cd80 | 414 | from the Cygwin package ( http://sources.redhat.com/cygwin/ ) |
68fbfbd7 JH |
415 | |
416 | =item Ksh | |
417 | ||
f224927c | 418 | from the MKS Toolkit ( http://www.mks.com/ ), or the Bourne shell of |
1577cd80 | 419 | the U/WIN environment ( http://www.research.att.com/sw/tools/uwin/ ) |
68fbfbd7 JH |
420 | |
421 | =item Tcsh | |
422 | ||
f224927c | 423 | ftp://ftp.astron.com/pub/tcsh/ , see also |
68fbfbd7 JH |
424 | http://www.primate.wisc.edu/software/csh-tcsh-book/ |
425 | ||
426 | =item Zsh | |
427 | ||
ac9dac7f | 428 | http://www.zsh.org/ |
68fbfbd7 JH |
429 | |
430 | =back | |
431 | ||
614a1598 JH |
432 | MKS and U/WIN are commercial (U/WIN is free for educational and |
433 | research purposes), Cygwin is covered by the GNU Public License (but | |
434 | that shouldn't matter for Perl use). The Cygwin, MKS, and U/WIN all | |
435 | contain (in addition to the shells) a comprehensive set of standard | |
436 | UNIX toolkit utilities. | |
8782d048 | 437 | |
5a13f98a JH |
438 | If you're transferring text files between Unix and Windows using FTP |
439 | be sure to transfer them in ASCII mode so the ends of lines are | |
440 | appropriately converted. | |
441 | ||
e083a89c JH |
442 | On Mac OS the MacPerl Application comes with a simple 32k text editor |
443 | that behaves like a rudimentary IDE. In contrast to the MacPerl Application | |
733271b5 | 444 | the MPW Perl tool can make use of the MPW Shell itself as an editor (with |
68fbfbd7 JH |
445 | no 32k limit). |
446 | ||
447 | =over 4 | |
448 | ||
c98c5709 | 449 | =item Affrus |
68fbfbd7 | 450 | |
d7f8936a | 451 | is a full Perl development environment with full debugger support |
7678cced | 452 | ( http://www.latenightsw.com ). |
68fbfbd7 JH |
453 | |
454 | =item Alpha | |
455 | ||
456 | is an editor, written and extensible in Tcl, that nonetheless has | |
733271b5 | 457 | built in support for several popular markup and programming languages |
c98c5709 RGS |
458 | including Perl and HTML ( http://www.his.com/~jguyer/Alpha/Alpha8.html ). |
459 | ||
460 | =item BBEdit and BBEdit Lite | |
461 | ||
462 | are text editors for Mac OS that have a Perl sensitivity mode | |
463 | ( http://web.barebones.com/ ). | |
464 | ||
68fbfbd7 JH |
465 | |
466 | =back | |
467 | ||
468 | Pepper and Pe are programming language sensitive text editors for Mac | |
1577cd80 | 469 | OS X and BeOS respectively ( http://www.hekkelman.com/ ). |
68dc0745 | 470 | |
471 | =head2 Where can I get Perl macros for vi? | |
472 | ||
473 | For a complete version of Tom Christiansen's vi configuration file, | |
a93751fa | 474 | see http://www.cpan.org/authors/Tom_Christiansen/scripts/toms.exrc.gz , |
a6dd486b | 475 | the standard benchmark file for vi emulators. The file runs best with nvi, |
5a964f20 | 476 | the current version of vi out of Berkeley, which incidentally can be built |
bfeeaf1b | 477 | with an embedded Perl interpreter--see http://www.cpan.org/src/misc/ . |
68dc0745 | 478 | |
479 | =head2 Where can I get perl-mode for emacs? | |
480 | ||
481 | Since Emacs version 19 patchlevel 22 or so, there have been both a | |
87275199 | 482 | perl-mode.el and support for the Perl debugger built in. These should |
68dc0745 | 483 | come with the standard Emacs 19 distribution. |
484 | ||
87275199 | 485 | In the Perl source directory, you'll find a directory called "emacs", |
68dc0745 | 486 | which contains a cperl-mode that color-codes keywords, provides |
487 | context-sensitive help, and other nifty things. | |
488 | ||
92c2ed05 | 489 | Note that the perl-mode of emacs will have fits with C<"main'foo"> |
d92eb7b0 | 490 | (single quote), and mess up the indentation and highlighting. You |
65acb1b1 | 491 | are probably using C<"main::foo"> in new Perl code anyway, so this |
92c2ed05 | 492 | shouldn't be an issue. |
68dc0745 | 493 | |
494 | =head2 How can I use curses with Perl? | |
495 | ||
496 | The Curses module from CPAN provides a dynamically loadable object | |
5a964f20 | 497 | module interface to a curses library. A small demo can be found at the |
49d635f9 | 498 | directory http://www.cpan.org/authors/Tom_Christiansen/scripts/rep.gz ; |
5a964f20 TC |
499 | this program repeats a command and updates the screen as needed, rendering |
500 | B<rep ps axu> similar to B<top>. | |
68dc0745 | 501 | |
c195e131 RGS |
502 | =head2 How can I write a GUI (X, Tk, Gtk, etc.) in Perl? |
503 | X<GUI> X<Tk> X<Wx> X<WxWidgets> X<Gtk> X<Gtk2> X<CamelBones> X<Qt> | |
68dc0745 | 504 | |
c195e131 | 505 | (contributed by Ben Morrow) |
68dc0745 | 506 | |
c195e131 RGS |
507 | There are a number of modules which let you write GUIs in Perl. Most |
508 | GUI toolkits have a perl interface: an incomplete list follows. | |
509 | ||
510 | =over 4 | |
511 | ||
512 | =item Tk | |
513 | ||
514 | This works under Unix and Windows, and the current version doesn't | |
515 | look half as bad under Windows as it used to. Some of the gui elements | |
516 | still don't 'feel' quite right, though. The interface is very natural | |
517 | and 'perlish', making it easy to use in small scripts that just need a | |
518 | simple gui. It hasn't been updated in a while. | |
519 | ||
520 | =item Wx | |
521 | ||
522 | This is a Perl binding for the cross-platform wxWidgets toolkit | |
523 | L<http://www.wxwidgets.org>. It works under Unix, Win32 and Mac OS X, | |
524 | using native widgets (Gtk under Unix). The interface follows the C++ | |
525 | interface closely, but the documentation is a little sparse for someone | |
526 | who doesn't know the library, mostly just referring you to the C++ | |
527 | documentation. | |
528 | ||
529 | =item Gtk and Gtk2 | |
530 | ||
531 | These are Perl bindings for the Gtk toolkit L<http://www.gtk.org>. The | |
532 | interface changed significantly between versions 1 and 2 so they have | |
533 | separate Perl modules. It runs under Unix, Win32 and Mac OS X (currently | |
534 | it requires an X server on Mac OS, but a 'native' port is underway), and | |
535 | the widgets look the same on every plaform: i.e., they don't match the | |
536 | native widgets. As with Wx, the Perl bindings follow the C API closely, | |
537 | and the documentation requires you to read the C documentation to | |
538 | understand it. | |
539 | ||
540 | =item Win32::GUI | |
541 | ||
542 | This provides access to most of the Win32 GUI widgets from Perl. | |
543 | Obviously, it only runs under Win32, and uses native widgets. The Perl | |
544 | interface doesn't really follow the C interface: it's been made more | |
545 | Perlish, and the documentation is pretty good. More advanced stuff may | |
546 | require familiarity with the C Win32 APIs, or reference to MSDN. | |
547 | ||
548 | =item CamelBones | |
549 | ||
550 | CamelBones L<http://camelbones.sourceforge.net> is a Perl interface to | |
551 | Mac OS X's Cocoa GUI toolkit, and as such can be used to produce native | |
552 | GUIs on Mac OS X. It's not on CPAN, as it requires frameworks that | |
553 | CPAN.pm doesn't know how to install, but installation is via the | |
554 | standard OSX package installer. The Perl API is, again, very close to | |
555 | the ObjC API it's wrapping, and the documentation just tells you how to | |
556 | translate from one to the other. | |
557 | ||
558 | =item Qt | |
559 | ||
560 | There is a Perl interface to TrollTech's Qt toolkit, but it does not | |
561 | appear to be maintained. | |
562 | ||
563 | =item Athena | |
564 | ||
565 | Sx is an interface to the Athena widget set which comes with X, but | |
566 | again it appears not to be much used nowadays. | |
567 | ||
568 | =back | |
92c2ed05 | 569 | |
68dc0745 | 570 | =head2 How can I make my Perl program run faster? |
571 | ||
92c2ed05 | 572 | The best way to do this is to come up with a better algorithm. This |
b73a15ae | 573 | can often make a dramatic difference. Jon Bentley's book |
5cd0b561 | 574 | I<Programming Pearls> (that's not a misspelling!) has some good tips |
92c2ed05 GS |
575 | on optimization, too. Advice on benchmarking boils down to: benchmark |
576 | and profile to make sure you're optimizing the right part, look for | |
577 | better algorithms instead of microtuning your code, and when all else | |
57b19278 | 578 | fails consider just buying faster hardware. You will probably want to |
b432a672 AL |
579 | read the answer to the earlier question "How do I profile my Perl |
580 | programs?" if you haven't done so already. | |
68dc0745 | 581 | |
92c2ed05 | 582 | A different approach is to autoload seldom-used Perl code. See the |
68dc0745 | 583 | AutoSplit and AutoLoader modules in the standard distribution for |
584 | that. Or you could locate the bottleneck and think about writing just | |
585 | that part in C, the way we used to take bottlenecks in C code and | |
5cd0b561 RGS |
586 | write them in assembler. Similar to rewriting in C, modules that have |
587 | critical sections can be written in C (for instance, the PDL module | |
588 | from CPAN). | |
589 | ||
590 | If you're currently linking your perl executable to a shared | |
591 | I<libc.so>, you can often gain a 10-25% performance benefit by | |
592 | rebuilding it to link with a static libc.a instead. This will make a | |
593 | bigger perl executable, but your Perl programs (and programmers) may | |
594 | thank you for it. See the F<INSTALL> file in the source distribution | |
595 | for more information. | |
596 | ||
597 | The undump program was an ancient attempt to speed up Perl program by | |
598 | storing the already-compiled form to disk. This is no longer a viable | |
599 | option, as it only worked on a few architectures, and wasn't a good | |
600 | solution anyway. | |
68dc0745 | 601 | |
602 | =head2 How can I make my Perl program take less memory? | |
603 | ||
604 | When it comes to time-space tradeoffs, Perl nearly always prefers to | |
605 | throw memory at a problem. Scalars in Perl use more memory than | |
65acb1b1 | 606 | strings in C, arrays take more than that, and hashes use even more. While |
68dc0745 | 607 | there's still a lot to be done, recent releases have been addressing |
608 | these issues. For example, as of 5.004, duplicate hash keys are | |
609 | shared amongst all hashes using them, so require no reallocation. | |
610 | ||
611 | In some cases, using substr() or vec() to simulate arrays can be | |
612 | highly beneficial. For example, an array of a thousand booleans will | |
613 | take at least 20,000 bytes of space, but it can be turned into one | |
a6dd486b | 614 | 125-byte bit vector--a considerable memory savings. The standard |
68dc0745 | 615 | Tie::SubstrHash module can also help for certain types of data |
616 | structure. If you're working with specialist data structures | |
617 | (matrices, for instance) modules that implement these in C may use | |
618 | less memory than equivalent Perl modules. | |
619 | ||
620 | Another thing to try is learning whether your Perl was compiled with | |
54310121 | 621 | the system malloc or with Perl's builtin malloc. Whichever one it |
68dc0745 | 622 | is, try using the other one and see whether this makes a difference. |
623 | Information about malloc is in the F<INSTALL> file in the source | |
624 | distribution. You can find out whether you are using perl's malloc by | |
625 | typing C<perl -V:usemymalloc>. | |
626 | ||
24f1ba9b JH |
627 | Of course, the best way to save memory is to not do anything to waste |
628 | it in the first place. Good programming practices can go a long way | |
629 | toward this: | |
630 | ||
631 | =over 4 | |
632 | ||
633 | =item * Don't slurp! | |
634 | ||
635 | Don't read an entire file into memory if you can process it line | |
636 | by line. Or more concretely, use a loop like this: | |
637 | ||
638 | # | |
639 | # Good Idea | |
640 | # | |
641 | while (<FILE>) { | |
642 | # ... | |
643 | } | |
644 | ||
645 | instead of this: | |
646 | ||
647 | # | |
648 | # Bad Idea | |
649 | # | |
650 | @data = <FILE>; | |
651 | foreach (@data) { | |
652 | # ... | |
653 | } | |
654 | ||
655 | When the files you're processing are small, it doesn't much matter which | |
656 | way you do it, but it makes a huge difference when they start getting | |
197aec24 | 657 | larger. |
24f1ba9b | 658 | |
bc06af74 JH |
659 | =item * Use map and grep selectively |
660 | ||
661 | Remember that both map and grep expect a LIST argument, so doing this: | |
662 | ||
663 | @wanted = grep {/pattern/} <FILE>; | |
664 | ||
665 | will cause the entire file to be slurped. For large files, it's better | |
666 | to loop: | |
667 | ||
668 | while (<FILE>) { | |
669 | push(@wanted, $_) if /pattern/; | |
670 | } | |
671 | ||
672 | =item * Avoid unnecessary quotes and stringification | |
673 | ||
674 | Don't quote large strings unless absolutely necessary: | |
675 | ||
676 | my $copy = "$large_string"; | |
677 | ||
678 | makes 2 copies of $large_string (one for $copy and another for the | |
679 | quotes), whereas | |
680 | ||
681 | my $copy = $large_string; | |
682 | ||
683 | only makes one copy. | |
684 | ||
685 | Ditto for stringifying large arrays: | |
686 | ||
687 | { | |
688 | local $, = "\n"; | |
689 | print @big_array; | |
690 | } | |
691 | ||
692 | is much more memory-efficient than either | |
693 | ||
694 | print join "\n", @big_array; | |
695 | ||
696 | or | |
697 | ||
698 | { | |
699 | local $" = "\n"; | |
700 | print "@big_array"; | |
701 | } | |
702 | ||
703 | ||
24f1ba9b JH |
704 | =item * Pass by reference |
705 | ||
706 | Pass arrays and hashes by reference, not by value. For one thing, it's | |
707 | the only way to pass multiple lists or hashes (or both) in a single | |
708 | call/return. It also avoids creating a copy of all the contents. This | |
c195e131 | 709 | requires some judgement, however, because any changes will be propagated |
24f1ba9b JH |
710 | back to the original data. If you really want to mangle (er, modify) a |
711 | copy, you'll have to sacrifice the memory needed to make one. | |
712 | ||
713 | =item * Tie large variables to disk. | |
714 | ||
715 | For "big" data stores (i.e. ones that exceed available memory) consider | |
716 | using one of the DB modules to store it on disk instead of in RAM. This | |
ed8cf1fe | 717 | will incur a penalty in access time, but that's probably better than |
24f1ba9b JH |
718 | causing your hard disk to thrash due to massive swapping. |
719 | ||
720 | =back | |
721 | ||
49d635f9 | 722 | =head2 Is it safe to return a reference to local or lexical data? |
68dc0745 | 723 | |
49d635f9 RGS |
724 | Yes. Perl's garbage collection system takes care of this so |
725 | everything works out right. | |
68dc0745 | 726 | |
727 | sub makeone { | |
728 | my @a = ( 1 .. 10 ); | |
729 | return \@a; | |
730 | } | |
731 | ||
197aec24 | 732 | for ( 1 .. 10 ) { |
68dc0745 | 733 | push @many, makeone(); |
734 | } | |
735 | ||
736 | print $many[4][5], "\n"; | |
737 | ||
738 | print "@many\n"; | |
739 | ||
740 | =head2 How can I free an array or hash so my program shrinks? | |
741 | ||
7678cced RGS |
742 | (contributed by Michael Carman) |
743 | ||
744 | You usually can't. Memory allocated to lexicals (i.e. my() variables) | |
745 | cannot be reclaimed or reused even if they go out of scope. It is | |
746 | reserved in case the variables come back into scope. Memory allocated | |
747 | to global variables can be reused (within your program) by using | |
748 | undef()ing and/or delete(). | |
749 | ||
750 | On most operating systems, memory allocated to a program can never be | |
751 | returned to the system. That's why long-running programs sometimes re- | |
752 | exec themselves. Some operating systems (notably, systems that use | |
753 | mmap(2) for allocating large chunks of memory) can reclaim memory that | |
754 | is no longer used, but on such systems, perl must be configured and | |
755 | compiled to use the OS's malloc, not perl's. | |
756 | ||
46fc3d4c | 757 | In general, memory allocation and de-allocation isn't something you can |
7678cced RGS |
758 | or should be worrying about much in Perl. |
759 | ||
760 | See also "How can I make my Perl program take less memory?" | |
68dc0745 | 761 | |
762 | =head2 How can I make my CGI script more efficient? | |
763 | ||
764 | Beyond the normal measures described to make general Perl programs | |
765 | faster or smaller, a CGI program has additional issues. It may be run | |
766 | several times per second. Given that each time it runs it will need | |
46fc3d4c | 767 | to be re-compiled and will often allocate a megabyte or more of system |
68dc0745 | 768 | memory, this can be a killer. Compiling into C B<isn't going to help |
46fc3d4c | 769 | you> because the process start-up overhead is where the bottleneck is. |
68dc0745 | 770 | |
92c2ed05 GS |
771 | There are two popular ways to avoid this overhead. One solution |
772 | involves running the Apache HTTP server (available from | |
f224927c | 773 | http://www.apache.org/ ) with either of the mod_perl or mod_fastcgi |
92c2ed05 GS |
774 | plugin modules. |
775 | ||
776 | With mod_perl and the Apache::Registry module (distributed with | |
777 | mod_perl), httpd will run with an embedded Perl interpreter which | |
778 | pre-compiles your script and then executes it within the same address | |
779 | space without forking. The Apache extension also gives Perl access to | |
780 | the internal server API, so modules written in Perl can do just about | |
781 | anything a module written in C can. For more on mod_perl, see | |
782 | http://perl.apache.org/ | |
783 | ||
65acb1b1 | 784 | With the FCGI module (from CPAN) and the mod_fastcgi |
bfeeaf1b | 785 | module (available from http://www.fastcgi.com/ ) each of your Perl |
87275199 | 786 | programs becomes a permanent CGI daemon process. |
68dc0745 | 787 | |
788 | Both of these solutions can have far-reaching effects on your system | |
87275199 | 789 | and on the way you write your CGI programs, so investigate them with |
68dc0745 | 790 | care. |
791 | ||
a93751fa | 792 | See http://www.cpan.org/modules/by-category/15_World_Wide_Web_HTML_HTTP_CGI/ . |
5a964f20 | 793 | |
68dc0745 | 794 | =head2 How can I hide the source for my Perl program? |
795 | ||
796 | Delete it. :-) Seriously, there are a number of (mostly | |
b432a672 | 797 | unsatisfactory) solutions with varying levels of "security". |
68dc0745 | 798 | |
799 | First of all, however, you I<can't> take away read permission, because | |
800 | the source code has to be readable in order to be compiled and | |
801 | interpreted. (That doesn't mean that a CGI script's source is | |
a6dd486b JB |
802 | readable by people on the web, though--only by people with access to |
803 | the filesystem.) So you have to leave the permissions at the socially | |
92c2ed05 | 804 | friendly 0755 level. |
68dc0745 | 805 | |
806 | Some people regard this as a security problem. If your program does | |
a6dd486b | 807 | insecure things and relies on people not knowing how to exploit those |
68dc0745 | 808 | insecurities, it is not secure. It is often possible for someone to |
809 | determine the insecure things and exploit them without viewing the | |
810 | source. Security through obscurity, the name for hiding your bugs | |
811 | instead of fixing them, is little security indeed. | |
812 | ||
83df6a1d JH |
813 | You can try using encryption via source filters (Starting from Perl |
814 | 5.8 the Filter::Simple and Filter::Util::Call modules are included in | |
815 | the standard distribution), but any decent programmer will be able to | |
816 | decrypt it. You can try using the byte code compiler and interpreter | |
ac9dac7f RGS |
817 | described later in L<perlfaq3>, but the curious might still be able to |
818 | de-compile it. You can try using the native-code compiler described | |
819 | later, but crackers might be able to disassemble it. These pose | |
820 | varying degrees of difficulty to people wanting to get at your code, | |
821 | but none can definitively conceal it (true of every language, not just | |
822 | Perl). | |
68dc0745 | 823 | |
49d635f9 RGS |
824 | It is very easy to recover the source of Perl programs. You simply |
825 | feed the program to the perl interpreter and use the modules in | |
826 | the B:: hierarchy. The B::Deparse module should be able to | |
827 | defeat most attempts to hide source. Again, this is not | |
828 | unique to Perl. | |
829 | ||
68dc0745 | 830 | If you're concerned about people profiting from your code, then the |
d92eb7b0 | 831 | bottom line is that nothing but a restrictive license will give you |
68dc0745 | 832 | legal security. License your software and pepper it with threatening |
b432a672 | 833 | statements like "This is unpublished proprietary software of XYZ Corp. |
68dc0745 | 834 | Your access to it does not give you permission to use it blah blah |
b432a672 | 835 | blah." We are not lawyers, of course, so you should see a lawyer if |
d92eb7b0 | 836 | you want to be sure your license's wording will stand up in court. |
68dc0745 | 837 | |
54310121 | 838 | =head2 How can I compile my Perl program into byte code or C? |
68dc0745 | 839 | |
7678cced RGS |
840 | (contributed by brian d foy) |
841 | ||
842 | In general, you can't do this. There are some things that may work | |
843 | for your situation though. People usually ask this question | |
6670e5e7 | 844 | because they want to distribute their works without giving away |
7678cced RGS |
845 | the source code, and most solutions trade disk space for convenience. |
846 | You probably won't see much of a speed increase either, since most | |
6670e5e7 | 847 | solutions simply bundle a Perl interpreter in the final product |
7678cced RGS |
848 | (but see L<How can I make my Perl program run faster?>). |
849 | ||
ac9dac7f | 850 | The Perl Archive Toolkit ( http://par.perl.org/ ) is Perl's |
9e72e4c6 RGS |
851 | analog to Java's JAR. It's freely available and on CPAN ( |
852 | http://search.cpan.org/dist/PAR/ ). | |
7678cced | 853 | |
9e72e4c6 RGS |
854 | There are also some commercial products that may work for you, although |
855 | you have to buy a license for them. | |
7678cced | 856 | |
9e72e4c6 RGS |
857 | The Perl Dev Kit ( http://www.activestate.com/Products/Perl_Dev_Kit/ ) |
858 | from ActiveState can "Turn your Perl programs into ready-to-run | |
7678cced RGS |
859 | executables for HP-UX, Linux, Solaris and Windows." |
860 | ||
9e72e4c6 RGS |
861 | Perl2Exe ( http://www.indigostar.com/perl2exe.htm ) is a command line |
862 | program for converting perl scripts to executable files. It targets both | |
863 | Windows and unix platforms. | |
5a964f20 | 864 | |
92c2ed05 | 865 | =head2 How can I get C<#!perl> to work on [MS-DOS,NT,...]? |
68dc0745 | 866 | |
867 | For OS/2 just use | |
868 | ||
869 | extproc perl -S -your_switches | |
870 | ||
871 | as the first line in C<*.cmd> file (C<-S> due to a bug in cmd.exe's | |
b432a672 | 872 | "extproc" handling). For DOS one should first invent a corresponding |
fd1adc71 RGS |
873 | batch file and codify it in C<ALTERNATE_SHEBANG> (see the |
874 | F<dosish.h> file in the source distribution for more information). | |
68dc0745 | 875 | |
92c2ed05 GS |
876 | The Win95/NT installation, when using the ActiveState port of Perl, |
877 | will modify the Registry to associate the C<.pl> extension with the | |
d92eb7b0 GS |
878 | perl interpreter. If you install another port, perhaps even building |
879 | your own Win95/NT Perl from the standard sources by using a Windows port | |
d702ae42 | 880 | of gcc (e.g., with cygwin or mingw32), then you'll have to modify |
d92eb7b0 GS |
881 | the Registry yourself. In addition to associating C<.pl> with the |
882 | interpreter, NT people can use: C<SET PATHEXT=%PATHEXT%;.PL> to let them | |
883 | run the program C<install-linux.pl> merely by typing C<install-linux>. | |
68dc0745 | 884 | |
8e30f651 RGS |
885 | Under "Classic" MacOS, a perl program will have the appropriate Creator and |
886 | Type, so that double-clicking them will invoke the MacPerl application. | |
887 | Under Mac OS X, clickable apps can be made from any C<#!> script using Wil | |
888 | Sanchez' DropScript utility: http://www.wsanchez.net/software/ . | |
68dc0745 | 889 | |
890 | I<IMPORTANT!>: Whatever you do, PLEASE don't get frustrated, and just | |
891 | throw the perl interpreter into your cgi-bin directory, in order to | |
87275199 | 892 | get your programs working for a web server. This is an EXTREMELY big |
68dc0745 | 893 | security risk. Take the time to figure out how to do it correctly. |
894 | ||
87275199 | 895 | =head2 Can I write useful Perl programs on the command line? |
68dc0745 | 896 | |
897 | Yes. Read L<perlrun> for more information. Some examples follow. | |
898 | (These assume standard Unix shell quoting rules.) | |
899 | ||
900 | # sum first and last fields | |
5a964f20 | 901 | perl -lane 'print $F[0] + $F[-1]' * |
68dc0745 | 902 | |
903 | # identify text files | |
904 | perl -le 'for(@ARGV) {print if -f && -T _}' * | |
905 | ||
5a964f20 | 906 | # remove (most) comments from C program |
68dc0745 | 907 | perl -0777 -pe 's{/\*.*?\*/}{}gs' foo.c |
908 | ||
909 | # make file a month younger than today, defeating reaper daemons | |
910 | perl -e '$X=24*60*60; utime(time(),time() + 30 * $X,@ARGV)' * | |
911 | ||
912 | # find first unused uid | |
913 | perl -le '$i++ while getpwuid($i); print $i' | |
914 | ||
915 | # display reasonable manpath | |
916 | echo $PATH | perl -nl -072 -e ' | |
917 | s![^/+]*$!man!&&-d&&!$s{$_}++&&push@m,$_;END{print"@m"}' | |
918 | ||
87275199 | 919 | OK, the last one was actually an Obfuscated Perl Contest entry. :-) |
68dc0745 | 920 | |
87275199 | 921 | =head2 Why don't Perl one-liners work on my DOS/Mac/VMS system? |
68dc0745 | 922 | |
923 | The problem is usually that the command interpreters on those systems | |
924 | have rather different ideas about quoting than the Unix shells under | |
925 | which the one-liners were created. On some systems, you may have to | |
926 | change single-quotes to double ones, which you must I<NOT> do on Unix | |
927 | or Plan9 systems. You might also have to change a single % to a %%. | |
928 | ||
929 | For example: | |
930 | ||
e573f903 | 931 | # Unix (including Mac OS X) |
68dc0745 | 932 | perl -e 'print "Hello world\n"' |
933 | ||
46fc3d4c | 934 | # DOS, etc. |
68dc0745 | 935 | perl -e "print \"Hello world\n\"" |
936 | ||
e573f903 | 937 | # Mac Classic |
68dc0745 | 938 | print "Hello world\n" |
939 | (then Run "Myscript" or Shift-Command-R) | |
940 | ||
d2321c93 JH |
941 | # MPW |
942 | perl -e 'print "Hello world\n"' | |
943 | ||
68dc0745 | 944 | # VMS |
945 | perl -e "print ""Hello world\n""" | |
946 | ||
a6dd486b | 947 | The problem is that none of these examples are reliable: they depend on the |
92c2ed05 | 948 | command interpreter. Under Unix, the first two often work. Under DOS, |
a6dd486b | 949 | it's entirely possible that neither works. If 4DOS was the command shell, |
92c2ed05 | 950 | you'd probably have better luck like this: |
68dc0745 | 951 | |
952 | perl -e "print <Ctrl-x>"Hello world\n<Ctrl-x>"" | |
953 | ||
46fc3d4c | 954 | Under the Mac, it depends which environment you are using. The MacPerl |
68dc0745 | 955 | shell, or MPW, is much like Unix shells in its support for several |
46fc3d4c | 956 | quoting variants, except that it makes free use of the Mac's non-ASCII |
68dc0745 | 957 | characters as control characters. |
958 | ||
65acb1b1 TC |
959 | Using qq(), q(), and qx(), instead of "double quotes", 'single |
960 | quotes', and `backticks`, may make one-liners easier to write. | |
961 | ||
d2321c93 | 962 | There is no general solution to all of this. It is a mess. |
68dc0745 | 963 | |
964 | [Some of this answer was contributed by Kenneth Albanowski.] | |
965 | ||
966 | =head2 Where can I learn about CGI or Web programming in Perl? | |
967 | ||
968 | For modules, get the CGI or LWP modules from CPAN. For textbooks, | |
969 | see the two especially dedicated to web stuff in the question on | |
b432a672 AL |
970 | books. For problems and questions related to the web, like "Why |
971 | do I get 500 Errors" or "Why doesn't it run from the browser right | |
972 | when it runs fine on the command line", see the troubleshooting | |
8305e449 | 973 | guides and references in L<perlfaq9> or in the CGI MetaFAQ: |
68dc0745 | 974 | |
8305e449 | 975 | http://www.perl.org/CGI_MetaFAQ.html |
0f542199 | 976 | |
68dc0745 | 977 | =head2 Where can I learn about object-oriented Perl programming? |
978 | ||
a6dd486b | 979 | A good place to start is L<perltoot>, and you can use L<perlobj>, |
06a5f41f | 980 | L<perlboot>, L<perltoot>, L<perltooc>, and L<perlbot> for reference. |
06a5f41f JH |
981 | |
982 | A good book on OO on Perl is the "Object-Oriented Perl" | |
e573f903 | 983 | by Damian Conway from Manning Publications, or "Intermediate Perl" |
ac9dac7f | 984 | by Randal Schwartz, brian d foy, and Tom Phoenix from O'Reilly Media. |
68dc0745 | 985 | |
b68463f7 | 986 | =head2 Where can I learn about linking C with Perl? |
68dc0745 | 987 | |
988 | If you want to call C from Perl, start with L<perlxstut>, | |
989 | moving on to L<perlxs>, L<xsubpp>, and L<perlguts>. If you want to | |
990 | call Perl from C, then read L<perlembed>, L<perlcall>, and | |
991 | L<perlguts>. Don't forget that you can learn a lot from looking at | |
992 | how the authors of existing extension modules wrote their code and | |
993 | solved their problems. | |
994 | ||
b68463f7 RGS |
995 | You might not need all the power of XS. The Inline::C module lets |
996 | you put C code directly in your Perl source. It handles all the | |
58103a2e | 997 | magic to make it work. You still have to learn at least some of |
b68463f7 RGS |
998 | the perl API but you won't have to deal with the complexity of the |
999 | XS support files. | |
1000 | ||
7678cced | 1001 | =head2 I've read perlembed, perlguts, etc., but I can't embed perl in my C program; what am I doing wrong? |
68dc0745 | 1002 | |
1003 | Download the ExtUtils::Embed kit from CPAN and run `make test'. If | |
1004 | the tests pass, read the pods again and again and again. If they | |
87275199 | 1005 | fail, see L<perlbug> and send a bug report with the output of |
68dc0745 | 1006 | C<make test TEST_VERBOSE=1> along with C<perl -V>. |
1007 | ||
83ded9ee | 1008 | =head2 When I tried to run my script, I got this message. What does it mean? |
68dc0745 | 1009 | |
87275199 GS |
1010 | A complete list of Perl's error messages and warnings with explanatory |
1011 | text can be found in L<perldiag>. You can also use the splain program | |
1012 | (distributed with Perl) to explain the error messages: | |
68dc0745 | 1013 | |
1014 | perl program 2>diag.out | |
1015 | splain [-v] [-p] diag.out | |
1016 | ||
1017 | or change your program to explain the messages for you: | |
1018 | ||
1019 | use diagnostics; | |
1020 | ||
1021 | or | |
1022 | ||
1023 | use diagnostics -verbose; | |
1024 | ||
1025 | =head2 What's MakeMaker? | |
1026 | ||
ac9dac7f RGS |
1027 | (contributed by brian d foy) |
1028 | ||
1029 | The C<ExtUtils::MakeMaker> module, better known simply as "MakeMaker", | |
1030 | turns a Perl script, typically called C<Makefile.PL>, into a Makefile. | |
1031 | The unix tool C<make> uses this file to manage dependencies and actions | |
1032 | to process and install a Perl distribution. | |
68dc0745 | 1033 | |
500071f4 RGS |
1034 | =head1 REVISION |
1035 | ||
c195e131 | 1036 | Revision: $Revision: 10127 $ |
500071f4 | 1037 | |
c195e131 | 1038 | Date: $Date: 2007-10-27 21:40:20 +0200 (Sat, 27 Oct 2007) $ |
500071f4 RGS |
1039 | |
1040 | See L<perlfaq> for source control details and availability. | |
1041 | ||
68dc0745 | 1042 | =head1 AUTHOR AND COPYRIGHT |
1043 | ||
ee891a00 | 1044 | Copyright (c) 1997-2007 Tom Christiansen, Nathan Torkington, and |
7678cced | 1045 | other authors as noted. All rights reserved. |
5a964f20 | 1046 | |
5a7beb56 JH |
1047 | This documentation is free; you can redistribute it and/or modify it |
1048 | under the same terms as Perl itself. | |
c8db1d39 | 1049 | |
87275199 | 1050 | Irrespective of its distribution, all code examples here are in the public |
c8db1d39 TC |
1051 | domain. You are permitted and encouraged to use this code and any |
1052 | derivatives thereof in your own programs for fun or for profit as you | |
1053 | see fit. A simple comment in the code giving credit to the FAQ would | |
1054 | be courteous but is not required. |