Commit | Line | Data |
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68dc0745 | 1 | =head1 NAME |
2 | ||
109f0441 | 3 | perlfaq3 - Programming Tools |
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 | |
3bc3c5be | 34 | C<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 | ||
3bc3c5be | 45 | The C<psh> (Perl sh) is currently at version 1.8. The Perl Shell is a shell |
a05e4845 RGS |
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 | |
3bc3c5be | 49 | control-flow statements and other things. You can get C<psh> at |
a05e4845 | 50 | http://sourceforge.net/projects/psh/ . |
55e174a4 | 51 | |
3bc3c5be | 52 | C<Zoidberg> is a similar project and provides a shell written in perl, |
f3b9614f | 53 | configured in perl and operated in perl. It is intended as a login shell |
109f0441 S |
54 | and development environment. It can be found at |
55 | http://pardus-larus.student.utwente.nl/~pardus/projects/zoidberg/ | |
f3b9614f RGS |
56 | or your local CPAN mirror. |
57 | ||
3bc3c5be | 58 | The C<Shell.pm> module (distributed with Perl) makes Perl try commands |
59 | which aren't part of the Perl language as shell commands. C<perlsh> from | |
a05e4845 RGS |
60 | the source distribution is simplistic and uninteresting, but may still |
61 | be what you want. | |
68dc0745 | 62 | |
49d635f9 RGS |
63 | =head2 How do I find which modules are installed on my system? |
64 | ||
109f0441 S |
65 | From the command line, you can use the C<cpan> command's C<-l> switch: |
66 | ||
67 | $ cpan -l | |
68 | ||
69 | You can also use C<cpan>'s C<-a> switch to create an autobundle file | |
589a5df2 | 70 | that C<CPAN.pm> understands and can use to re-install every module: |
109f0441 S |
71 | |
72 | $ cpan -a | |
73 | ||
3bc3c5be | 74 | Inside a Perl program, you can use the C<ExtUtils::Installed> module to |
109f0441 S |
75 | show all installed distributions, although it can take awhile to do |
76 | its magic. The standard library which comes with Perl just shows up | |
589a5df2 | 77 | as "Perl" (although you can get those with C<Module::CoreList>). |
49d635f9 RGS |
78 | |
79 | use ExtUtils::Installed; | |
197aec24 | 80 | |
49d635f9 RGS |
81 | my $inst = ExtUtils::Installed->new(); |
82 | my @modules = $inst->modules(); | |
83 | ||
84 | If you want a list of all of the Perl module filenames, you | |
589a5df2 | 85 | can use C<File::Find::Rule>: |
49d635f9 RGS |
86 | |
87 | use File::Find::Rule; | |
197aec24 | 88 | |
109f0441 S |
89 | my @files = File::Find::Rule-> |
90 | extras({follow => 1})-> | |
91 | file()-> | |
92 | name( '*.pm' )-> | |
93 | in( @INC ) | |
94 | ; | |
49d635f9 RGS |
95 | |
96 | If you do not have that module, you can do the same thing | |
3bc3c5be | 97 | with C<File::Find> which is part of the standard library: |
49d635f9 | 98 | |
109f0441 S |
99 | use File::Find; |
100 | my @files; | |
101 | ||
102 | find( | |
103 | { | |
104 | wanted => sub { | |
105 | push @files, $File::Find::fullname | |
106 | if -f $File::Find::fullname && /\.pm$/ | |
107 | }, | |
108 | follow => 1, | |
109 | follow_skip => 2, | |
110 | }, | |
111 | @INC | |
112 | ); | |
49d635f9 | 113 | |
a05e4845 | 114 | print join "\n", @files; |
197aec24 | 115 | |
49d635f9 RGS |
116 | If you simply need to quickly check to see if a module is |
117 | available, you can check for its documentation. If you can | |
197aec24 | 118 | read the documentation the module is most likely installed. |
49d635f9 | 119 | If you cannot read the documentation, the module might not |
589a5df2 | 120 | have any (in rare cases): |
49d635f9 | 121 | |
109f0441 | 122 | $ perldoc Module::Name |
49d635f9 RGS |
123 | |
124 | You can also try to include the module in a one-liner to see if | |
589a5df2 | 125 | perl finds it: |
49d635f9 | 126 | |
109f0441 | 127 | $ perl -MModule::Name -e1 |
197aec24 | 128 | |
68dc0745 | 129 | =head2 How do I debug my Perl programs? |
130 | ||
500071f4 RGS |
131 | (contributed by brian d foy) |
132 | ||
133 | Before you do anything else, you can help yourself by ensuring that | |
134 | you let Perl tell you about problem areas in your code. By turning | |
ac9dac7f | 135 | on warnings and strictures, you can head off many problems before |
500071f4 RGS |
136 | they get too big. You can find out more about these in L<strict> |
137 | and L<warnings>. | |
138 | ||
139 | #!/usr/bin/perl | |
140 | use strict; | |
141 | use warnings; | |
ac9dac7f | 142 | |
500071f4 RGS |
143 | Beyond that, the simplest debugger is the C<print> function. Use it |
144 | to look at values as you run your program: | |
145 | ||
146 | print STDERR "The value is [$value]\n"; | |
68dc0745 | 147 | |
500071f4 | 148 | The C<Data::Dumper> module can pretty-print Perl data structures: |
68dc0745 | 149 | |
ac9dac7f RGS |
150 | use Data::Dumper qw( Dumper ); |
151 | print STDERR "The hash is " . Dumper( \%hash ) . "\n"; | |
152 | ||
500071f4 RGS |
153 | Perl comes with an interactive debugger, which you can start with the |
154 | C<-d> switch. It's fully explained in L<perldebug>. | |
68dc0745 | 155 | |
3bc3c5be | 156 | If you'd like a graphical user interface and you have C<Tk>, you can use |
500071f4 | 157 | C<ptkdb>. It's on CPAN and available for free. |
68dc0745 | 158 | |
c195e131 | 159 | If you need something much more sophisticated and controllable, Leon |
3bc3c5be | 160 | Brocard's C<Devel::ebug> (which you can call with the C<-D> switch as C<-Debug>) |
500071f4 RGS |
161 | gives you the programmatic hooks into everything you need to write your |
162 | own (without too much pain and suffering). | |
92c2ed05 | 163 | |
500071f4 RGS |
164 | You can also use a commercial debugger such as Affrus (Mac OS X), Komodo |
165 | from Activestate (Windows and Mac OS X), or EPIC (most platforms). | |
68dc0745 | 166 | |
167 | =head2 How do I profile my Perl programs? | |
168 | ||
109f0441 S |
169 | (contributed by brian d foy, updated Fri Jul 25 12:22:26 PDT 2008) |
170 | ||
171 | The C<Devel> namespace has several modules which you can use to | |
172 | profile your Perl programs. The C<Devel::DProf> module comes with Perl | |
173 | and you can invoke it with the C<-d> switch: | |
174 | ||
175 | perl -d:DProf program.pl | |
176 | ||
177 | After running your program under C<DProf>, you'll get a F<tmon.out> file | |
178 | with the profile data. To look at the data, you can turn it into a | |
179 | human-readable report with the C<dprofpp> program that comes with | |
180 | C<Devel::DProf>. | |
181 | ||
182 | dprofpp | |
68dc0745 | 183 | |
109f0441 | 184 | You can also do the profiling and reporting in one step with the C<-p> |
3bc3c5be | 185 | switch to C<dprofpp>: |
92c2ed05 | 186 | |
109f0441 | 187 | dprofpp -p program.pl |
92c2ed05 | 188 | |
109f0441 S |
189 | The C<Devel::NYTProf> (New York Times Profiler) does both statement |
190 | and subroutine profiling. It's available from CPAN and you also invoke | |
191 | it with the C<-d> switch: | |
92c2ed05 | 192 | |
109f0441 | 193 | perl -d:NYTProf some_perl.pl |
92c2ed05 | 194 | |
109f0441 S |
195 | Like C<DProf>, it creates a database of the profile information that you |
196 | can turn into reports. The C<nytprofhtml> command turns the data into | |
197 | an HTML report similar to the C<Devel::Cover> report: | |
92c2ed05 | 198 | |
109f0441 | 199 | nytprofhtml |
92c2ed05 | 200 | |
109f0441 S |
201 | CPAN has several other profilers that you can invoke in the same |
202 | fashion. You might also be interested in using the C<Benchmark> to | |
203 | measure and compare code snippets. | |
204 | ||
205 | You can read more about profiling in I<Programming Perl>, chapter 20, | |
206 | or I<Mastering Perl>, chapter 5. | |
207 | ||
208 | L<perldebguts> documents creating a custom debugger if you need to | |
209 | create a special sort of profiler. brian d foy describes the process | |
210 | in I<The Perl Journal>, "Creating a Perl Debugger", | |
211 | http://www.ddj.com/184404522 , and "Profiling in Perl" | |
212 | http://www.ddj.com/184404580 . | |
213 | ||
214 | Perl.com has two interesting articles on profiling: "Profiling Perl", | |
215 | by Simon Cozens, http://www.perl.com/lpt/a/850 and "Debugging and | |
216 | Profiling mod_perl Applications", by Frank Wiles, | |
217 | http://www.perl.com/pub/a/2006/02/09/debug_mod_perl.html . | |
218 | ||
219 | Randal L. Schwartz writes about profiling in "Speeding up Your Perl | |
220 | Programs" for I<Unix Review>, | |
221 | http://www.stonehenge.com/merlyn/UnixReview/col49.html , and "Profiling | |
222 | in Template Toolkit via Overriding" for I<Linux Magazine>, | |
223 | http://www.stonehenge.com/merlyn/LinuxMag/col75.html . | |
65acb1b1 | 224 | |
68dc0745 | 225 | =head2 How do I cross-reference my Perl programs? |
226 | ||
3bc3c5be | 227 | The C<B::Xref> module can be used to generate cross-reference reports |
83ded9ee | 228 | for Perl programs. |
68dc0745 | 229 | |
c8db1d39 | 230 | perl -MO=Xref[,OPTIONS] scriptname.plx |
68dc0745 | 231 | |
232 | =head2 Is there a pretty-printer (formatter) for Perl? | |
233 | ||
3bc3c5be | 234 | C<Perltidy> is a Perl script which indents and reformats Perl scripts |
55e174a4 JH |
235 | to make them easier to read by trying to follow the rules of the |
236 | L<perlstyle>. If you write Perl scripts, or spend much time reading | |
237 | them, you will probably find it useful. It is available at | |
3bc3c5be | 238 | http://perltidy.sourceforge.net . |
55e174a4 JH |
239 | |
240 | Of course, if you simply follow the guidelines in L<perlstyle>, | |
241 | you shouldn't need to reformat. The habit of formatting your code | |
242 | as you write it will help prevent bugs. Your editor can and should | |
243 | help you with this. The perl-mode or newer cperl-mode for emacs | |
244 | can provide remarkable amounts of help with most (but not all) | |
245 | code, and even less programmable editors can provide significant | |
246 | assistance. Tom Christiansen and many other VI users swear by | |
247 | the following settings in vi and its clones: | |
65acb1b1 TC |
248 | |
249 | set ai sw=4 | |
d92eb7b0 | 250 | map! ^O {^M}^[O^T |
65acb1b1 | 251 | |
55e174a4 | 252 | Put that in your F<.exrc> file (replacing the caret characters |
65acb1b1 | 253 | with control characters) and away you go. In insert mode, ^T is |
ac9dac7f RGS |
254 | for indenting, ^D is for undenting, and ^O is for blockdenting--as |
255 | it were. A more complete example, with comments, can be found at | |
213329dd | 256 | http://www.cpan.org/authors/id/TOMC/scripts/toms.exrc.gz |
92c2ed05 | 257 | |
49d635f9 | 258 | The a2ps http://www-inf.enst.fr/%7Edemaille/a2ps/black+white.ps.gz does |
06a5f41f | 259 | lots of things related to generating nicely printed output of |
c195e131 | 260 | documents. |
65acb1b1 | 261 | |
d92eb7b0 | 262 | =head2 Is there a ctags for Perl? |
68dc0745 | 263 | |
b68463f7 RGS |
264 | (contributed by brian d foy) |
265 | ||
ac9dac7f RGS |
266 | Ctags uses an index to quickly find things in source code, and many |
267 | popular editors support ctags for several different languages, | |
268 | including Perl. | |
269 | ||
b68463f7 | 270 | Exuberent ctags supports Perl: http://ctags.sourceforge.net/ |
bc06af74 | 271 | |
b68463f7 | 272 | You might also try pltags: http://www.mscha.com/pltags.zip |
65acb1b1 TC |
273 | |
274 | =head2 Is there an IDE or Windows Perl Editor? | |
275 | ||
6641ed39 JH |
276 | Perl programs are just plain text, so any editor will do. |
277 | ||
23bec515 | 278 | If you're on Unix, you already have an IDE--Unix itself. The Unix |
6641ed39 JH |
279 | philosophy is the philosophy of several small tools that each do one |
280 | thing and do it well. It's like a carpenter's toolbox. | |
281 | ||
28b41a80 RGS |
282 | If you want an IDE, check the following (in alphabetical order, not |
283 | order of preference): | |
68fbfbd7 JH |
284 | |
285 | =over 4 | |
286 | ||
28b41a80 RGS |
287 | =item Eclipse |
288 | ||
b68463f7 RGS |
289 | http://e-p-i-c.sf.net/ |
290 | ||
6670e5e7 | 291 | The Eclipse Perl Integration Project integrates Perl |
28b41a80 RGS |
292 | editing/debugging with Eclipse. |
293 | ||
b68463f7 RGS |
294 | =item Enginsite |
295 | ||
296 | http://www.enginsite.com/ | |
297 | ||
298 | Perl Editor by EngInSite is a complete integrated development | |
299 | environment (IDE) for creating, testing, and debugging Perl scripts; | |
300 | the tool runs on Windows 9x/NT/2000/XP or later. | |
28b41a80 | 301 | |
68fbfbd7 JH |
302 | =item Komodo |
303 | ||
b68463f7 RGS |
304 | http://www.ActiveState.com/Products/Komodo/ |
305 | ||
28b41a80 RGS |
306 | ActiveState's cross-platform (as of October 2004, that's Windows, Linux, |
307 | and Solaris), multi-language IDE has Perl support, including a regular expression | |
b68463f7 | 308 | debugger and remote debugging. |
68fbfbd7 | 309 | |
589a5df2 | 310 | =item Notepad++ |
311 | ||
312 | http://notepad-plus.sourceforge.net/ | |
313 | ||
ac1094a1 JH |
314 | =item Open Perl IDE |
315 | ||
b68463f7 RGS |
316 | http://open-perl-ide.sourceforge.net/ |
317 | ||
ac1094a1 JH |
318 | Open Perl IDE is an integrated development environment for writing |
319 | and debugging Perl scripts with ActiveState's ActivePerl distribution | |
320 | under Windows 95/98/NT/2000. | |
321 | ||
28b41a80 RGS |
322 | =item OptiPerl |
323 | ||
b68463f7 RGS |
324 | http://www.optiperl.com/ |
325 | ||
326 | OptiPerl is a Windows IDE with simulated CGI environment, including | |
327 | debugger and syntax highlighting editor. | |
28b41a80 | 328 | |
109f0441 S |
329 | =item Padre |
330 | ||
331 | http://padre.perlide.org/ | |
332 | ||
589a5df2 | 333 | Padre is cross-platform IDE for Perl written in Perl using wxWidgets to provide |
334 | a native look and feel. It's open source under the Artistic License. | |
109f0441 | 335 | |
5ca69f12 JH |
336 | =item PerlBuilder |
337 | ||
b68463f7 RGS |
338 | http://www.solutionsoft.com/perl.htm |
339 | ||
109f0441 | 340 | PerlBuilder is an integrated development environment for Windows that |
b68463f7 | 341 | supports Perl development. |
8782d048 | 342 | |
68fbfbd7 JH |
343 | =item visiPerl+ |
344 | ||
b68463f7 RGS |
345 | http://helpconsulting.net/visiperl/ |
346 | ||
ac1094a1 | 347 | From Help Consulting, for Windows. |
68fbfbd7 | 348 | |
28b41a80 RGS |
349 | =item Visual Perl |
350 | ||
b68463f7 RGS |
351 | http://www.activestate.com/Products/Visual_Perl/ |
352 | ||
28b41a80 | 353 | Visual Perl is a Visual Studio.NET plug-in from ActiveState. |
29b1171f | 354 | |
b68463f7 RGS |
355 | =item Zeus |
356 | ||
357 | http://www.zeusedit.com/lookmain.html | |
358 | ||
359 | Zeus for Window is another Win32 multi-language editor/IDE | |
360 | that comes with support for Perl: | |
29b1171f | 361 | |
68fbfbd7 JH |
362 | =back |
363 | ||
b68463f7 RGS |
364 | For editors: if you're on Unix you probably have vi or a vi clone |
365 | already, and possibly an emacs too, so you may not need to download | |
366 | anything. In any emacs the cperl-mode (M-x cperl-mode) gives you | |
367 | perhaps the best available Perl editing mode in any editor. | |
368 | ||
369 | If you are using Windows, you can use any editor that lets you work | |
589a5df2 | 370 | with plain text, such as NotePad or WordPad. Word processors, such as |
b68463f7 RGS |
371 | Microsoft Word or WordPerfect, typically do not work since they insert |
372 | all sorts of behind-the-scenes information, although some allow you to | |
589a5df2 | 373 | save files as "Text Only". You can also download text editors designed |
374 | specifically for programming, such as Textpad ( | |
375 | http://www.textpad.com/ ) and UltraEdit ( http://www.ultraedit.com/ ), | |
376 | among others. | |
377 | ||
378 | If you are using MacOS, the same concerns apply. MacPerl (for Classic | |
379 | environments) comes with a simple editor. Popular external editors are | |
380 | BBEdit ( http://www.bbedit.com/ ) or Alpha ( | |
381 | http://www.his.com/~jguyer/Alpha/Alpha8.html ). MacOS X users can use | |
382 | Unix editors as well. | |
383 | ||
384 | =over 4 | |
385 | ||
386 | =item GNU Emacs | |
387 | ||
388 | http://www.gnu.org/software/emacs/windows/ntemacs.html | |
389 | ||
390 | =item MicroEMACS | |
391 | ||
392 | http://www.microemacs.de/ | |
393 | ||
394 | =item XEmacs | |
395 | ||
396 | http://www.xemacs.org/Download/index.html | |
397 | ||
398 | =item Jed | |
399 | ||
400 | http://space.mit.edu/~davis/jed/ | |
401 | ||
402 | =back | |
403 | ||
404 | or a vi clone such as | |
405 | ||
406 | =over 4 | |
407 | ||
408 | =item Elvis | |
409 | ||
410 | ftp://ftp.cs.pdx.edu/pub/elvis/ http://www.fh-wedel.de/elvis/ | |
411 | ||
412 | =item Vile | |
413 | ||
414 | http://dickey.his.com/vile/vile.html | |
415 | ||
416 | =item Vim | |
417 | ||
418 | http://www.vim.org/ | |
419 | ||
420 | =back | |
421 | ||
422 | For vi lovers in general, Windows or elsewhere: | |
423 | ||
424 | http://www.thomer.com/thomer/vi/vi.html | |
425 | ||
426 | nvi ( http://www.bostic.com/vi/ , available from CPAN in src/misc/) is | |
427 | yet another vi clone, unfortunately not available for Windows, but in | |
23bec515 | 428 | Unix platforms you might be interested in trying it out, firstly because |
589a5df2 | 429 | strictly speaking it is not a vi clone, it is the real vi, or the new |
430 | incarnation of it, and secondly because you can embed Perl inside it | |
431 | to use Perl as the scripting language. nvi is not alone in this, | |
432 | though: at least also vim and vile offer an embedded Perl. | |
433 | ||
434 | The following are Win32 multilanguage editor/IDEs that support Perl: | |
435 | ||
436 | =over 4 | |
437 | ||
438 | =item Codewright | |
439 | ||
440 | http://www.borland.com/codewright/ | |
441 | ||
442 | =item MultiEdit | |
443 | ||
444 | http://www.MultiEdit.com/ | |
445 | ||
446 | =item SlickEdit | |
447 | ||
448 | http://www.slickedit.com/ | |
449 | ||
450 | =item ConTEXT | |
451 | ||
452 | http://www.contexteditor.org/ | |
453 | ||
454 | =back | |
455 | ||
456 | There is also a toyedit Text widget based editor written in Perl | |
457 | that is distributed with the Tk module on CPAN. The ptkdb | |
458 | ( http://ptkdb.sourceforge.net/ ) is a Perl/tk based debugger that | |
459 | acts as a development environment of sorts. Perl Composer | |
460 | ( http://perlcomposer.sourceforge.net/ ) is an IDE for Perl/Tk | |
461 | GUI creation. | |
462 | ||
463 | In addition to an editor/IDE you might be interested in a more | |
464 | powerful shell environment for Win32. Your options include | |
465 | ||
466 | =over 4 | |
467 | ||
468 | =item Bash | |
469 | ||
470 | from the Cygwin package ( http://sources.redhat.com/cygwin/ ) | |
471 | ||
472 | =item Ksh | |
473 | ||
474 | from the MKS Toolkit ( http://www.mkssoftware.com/ ), or the Bourne shell of | |
475 | the U/WIN environment ( http://www.research.att.com/sw/tools/uwin/ ) | |
476 | ||
477 | =item Tcsh | |
478 | ||
479 | ftp://ftp.astron.com/pub/tcsh/ , see also | |
480 | http://www.primate.wisc.edu/software/csh-tcsh-book/ | |
481 | ||
482 | =item Zsh | |
483 | ||
484 | http://www.zsh.org/ | |
485 | ||
486 | =back | |
487 | ||
488 | MKS and U/WIN are commercial (U/WIN is free for educational and | |
489 | research purposes), Cygwin is covered by the GNU General Public | |
490 | License (but that shouldn't matter for Perl use). The Cygwin, MKS, | |
491 | and U/WIN all contain (in addition to the shells) a comprehensive set | |
23bec515 | 492 | of standard Unix toolkit utilities. |
589a5df2 | 493 | |
494 | If you're transferring text files between Unix and Windows using FTP | |
495 | be sure to transfer them in ASCII mode so the ends of lines are | |
496 | appropriately converted. | |
497 | ||
498 | On Mac OS the MacPerl Application comes with a simple 32k text editor | |
499 | that behaves like a rudimentary IDE. In contrast to the MacPerl Application | |
500 | the MPW Perl tool can make use of the MPW Shell itself as an editor (with | |
501 | no 32k limit). | |
502 | ||
503 | =over 4 | |
504 | ||
505 | =item Affrus | |
506 | ||
507 | is a full Perl development environment with full debugger support | |
508 | ( http://www.latenightsw.com ). | |
509 | ||
510 | =item Alpha | |
511 | ||
512 | is an editor, written and extensible in Tcl, that nonetheless has | |
513 | built in support for several popular markup and programming languages | |
514 | including Perl and HTML ( http://www.his.com/~jguyer/Alpha/Alpha8.html ). | |
515 | ||
516 | =item BBEdit and BBEdit Lite | |
517 | ||
518 | are text editors for Mac OS that have a Perl sensitivity mode | |
519 | ( http://web.barebones.com/ ). | |
520 | ||
521 | =back | |
522 | ||
523 | =head2 Where can I get Perl macros for vi? | |
524 | ||
525 | For a complete version of Tom Christiansen's vi configuration file, | |
526 | see http://www.cpan.org/authors/Tom_Christiansen/scripts/toms.exrc.gz , | |
527 | the standard benchmark file for vi emulators. The file runs best with nvi, | |
528 | the current version of vi out of Berkeley, which incidentally can be built | |
529 | with an embedded Perl interpreter--see http://www.cpan.org/src/misc/ . | |
530 | ||
531 | =head2 Where can I get perl-mode for emacs? | |
532 | ||
533 | Since Emacs version 19 patchlevel 22 or so, there have been both a | |
534 | perl-mode.el and support for the Perl debugger built in. These should | |
535 | come with the standard Emacs 19 distribution. | |
536 | ||
537 | In the Perl source directory, you'll find a directory called "emacs", | |
538 | which contains a cperl-mode that color-codes keywords, provides | |
539 | context-sensitive help, and other nifty things. | |
540 | ||
541 | Note that the perl-mode of emacs will have fits with C<"main'foo"> | |
542 | (single quote), and mess up the indentation and highlighting. You | |
543 | are probably using C<"main::foo"> in new Perl code anyway, so this | |
544 | shouldn't be an issue. | |
545 | ||
546 | =head2 How can I use curses with Perl? | |
547 | ||
548 | The Curses module from CPAN provides a dynamically loadable object | |
549 | module interface to a curses library. A small demo can be found at the | |
550 | directory http://www.cpan.org/authors/Tom_Christiansen/scripts/rep.gz ; | |
551 | this program repeats a command and updates the screen as needed, rendering | |
552 | B<rep ps axu> similar to B<top>. | |
553 | ||
554 | =head2 How can I write a GUI (X, Tk, Gtk, etc.) in Perl? | |
555 | X<GUI> X<Tk> X<Wx> X<WxWidgets> X<Gtk> X<Gtk2> X<CamelBones> X<Qt> | |
556 | ||
557 | (contributed by Ben Morrow) | |
558 | ||
559 | There are a number of modules which let you write GUIs in Perl. Most | |
560 | GUI toolkits have a perl interface: an incomplete list follows. | |
561 | ||
562 | =over 4 | |
563 | ||
564 | =item Tk | |
565 | ||
566 | This works under Unix and Windows, and the current version doesn't | |
567 | look half as bad under Windows as it used to. Some of the gui elements | |
568 | still don't 'feel' quite right, though. The interface is very natural | |
569 | and 'perlish', making it easy to use in small scripts that just need a | |
570 | simple gui. It hasn't been updated in a while. | |
571 | ||
572 | =item Wx | |
573 | ||
574 | This is a Perl binding for the cross-platform wxWidgets toolkit | |
575 | ( http://www.wxwidgets.org ). It works under Unix, Win32 and Mac OS X, | |
576 | using native widgets (Gtk under Unix). The interface follows the C++ | |
577 | interface closely, but the documentation is a little sparse for someone | |
578 | who doesn't know the library, mostly just referring you to the C++ | |
579 | documentation. | |
580 | ||
581 | =item Gtk and Gtk2 | |
582 | ||
583 | These are Perl bindings for the Gtk toolkit ( http://www.gtk.org ). The | |
584 | interface changed significantly between versions 1 and 2 so they have | |
585 | separate Perl modules. It runs under Unix, Win32 and Mac OS X (currently | |
586 | it requires an X server on Mac OS, but a 'native' port is underway), and | |
587 | the widgets look the same on every plaform: i.e., they don't match the | |
588 | native widgets. As with Wx, the Perl bindings follow the C API closely, | |
589 | and the documentation requires you to read the C documentation to | |
590 | understand it. | |
591 | ||
592 | =item Win32::GUI | |
593 | ||
594 | This provides access to most of the Win32 GUI widgets from Perl. | |
595 | Obviously, it only runs under Win32, and uses native widgets. The Perl | |
596 | interface doesn't really follow the C interface: it's been made more | |
597 | Perlish, and the documentation is pretty good. More advanced stuff may | |
598 | require familiarity with the C Win32 APIs, or reference to MSDN. | |
599 | ||
600 | =item CamelBones | |
601 | ||
602 | CamelBones ( http://camelbones.sourceforge.net ) is a Perl interface to | |
603 | Mac OS X's Cocoa GUI toolkit, and as such can be used to produce native | |
604 | GUIs on Mac OS X. It's not on CPAN, as it requires frameworks that | |
605 | CPAN.pm doesn't know how to install, but installation is via the | |
606 | standard OSX package installer. The Perl API is, again, very close to | |
607 | the ObjC API it's wrapping, and the documentation just tells you how to | |
608 | translate from one to the other. | |
609 | ||
610 | =item Qt | |
611 | ||
612 | There is a Perl interface to TrollTech's Qt toolkit, but it does not | |
613 | appear to be maintained. | |
614 | ||
615 | =item Athena | |
616 | ||
617 | Sx is an interface to the Athena widget set which comes with X, but | |
618 | again it appears not to be much used nowadays. | |
619 | ||
620 | =back | |
621 | ||
622 | =head2 How can I make my Perl program run faster? | |
623 | ||
624 | The best way to do this is to come up with a better algorithm. This | |
625 | can often make a dramatic difference. Jon Bentley's book | |
626 | I<Programming Pearls> (that's not a misspelling!) has some good tips | |
627 | on optimization, too. Advice on benchmarking boils down to: benchmark | |
628 | and profile to make sure you're optimizing the right part, look for | |
629 | better algorithms instead of microtuning your code, and when all else | |
630 | fails consider just buying faster hardware. You will probably want to | |
631 | read the answer to the earlier question "How do I profile my Perl | |
632 | programs?" if you haven't done so already. | |
633 | ||
634 | A different approach is to autoload seldom-used Perl code. See the | |
635 | AutoSplit and AutoLoader modules in the standard distribution for | |
636 | that. Or you could locate the bottleneck and think about writing just | |
637 | that part in C, the way we used to take bottlenecks in C code and | |
638 | write them in assembler. Similar to rewriting in C, modules that have | |
639 | critical sections can be written in C (for instance, the PDL module | |
640 | from CPAN). | |
641 | ||
642 | If you're currently linking your perl executable to a shared | |
643 | I<libc.so>, you can often gain a 10-25% performance benefit by | |
644 | rebuilding it to link with a static libc.a instead. This will make a | |
645 | bigger perl executable, but your Perl programs (and programmers) may | |
646 | thank you for it. See the F<INSTALL> file in the source distribution | |
647 | for more information. | |
648 | ||
649 | The undump program was an ancient attempt to speed up Perl program by | |
650 | storing the already-compiled form to disk. This is no longer a viable | |
651 | option, as it only worked on a few architectures, and wasn't a good | |
652 | solution anyway. | |
653 | ||
654 | =head2 How can I make my Perl program take less memory? | |
655 | ||
656 | When it comes to time-space tradeoffs, Perl nearly always prefers to | |
657 | throw memory at a problem. Scalars in Perl use more memory than | |
658 | strings in C, arrays take more than that, and hashes use even more. While | |
659 | there's still a lot to be done, recent releases have been addressing | |
660 | these issues. For example, as of 5.004, duplicate hash keys are | |
661 | shared amongst all hashes using them, so require no reallocation. | |
662 | ||
663 | In some cases, using substr() or vec() to simulate arrays can be | |
664 | highly beneficial. For example, an array of a thousand booleans will | |
665 | take at least 20,000 bytes of space, but it can be turned into one | |
666 | 125-byte bit vector--a considerable memory savings. The standard | |
667 | Tie::SubstrHash module can also help for certain types of data | |
668 | structure. If you're working with specialist data structures | |
669 | (matrices, for instance) modules that implement these in C may use | |
670 | less memory than equivalent Perl modules. | |
671 | ||
672 | Another thing to try is learning whether your Perl was compiled with | |
673 | the system malloc or with Perl's builtin malloc. Whichever one it | |
674 | is, try using the other one and see whether this makes a difference. | |
675 | Information about malloc is in the F<INSTALL> file in the source | |
676 | distribution. You can find out whether you are using perl's malloc by | |
677 | typing C<perl -V:usemymalloc>. | |
678 | ||
679 | Of course, the best way to save memory is to not do anything to waste | |
680 | it in the first place. Good programming practices can go a long way | |
681 | toward this: | |
682 | ||
683 | =over 4 | |
684 | ||
685 | =item * Don't slurp! | |
686 | ||
687 | Don't read an entire file into memory if you can process it line | |
688 | by line. Or more concretely, use a loop like this: | |
689 | ||
690 | # | |
691 | # Good Idea | |
692 | # | |
693 | while (<FILE>) { | |
694 | # ... | |
695 | } | |
696 | ||
697 | instead of this: | |
698 | ||
699 | # | |
700 | # Bad Idea | |
701 | # | |
702 | @data = <FILE>; | |
703 | foreach (@data) { | |
704 | # ... | |
705 | } | |
706 | ||
707 | When the files you're processing are small, it doesn't much matter which | |
708 | way you do it, but it makes a huge difference when they start getting | |
709 | larger. | |
710 | ||
711 | =item * Use map and grep selectively | |
712 | ||
713 | Remember that both map and grep expect a LIST argument, so doing this: | |
714 | ||
715 | @wanted = grep {/pattern/} <FILE>; | |
716 | ||
717 | will cause the entire file to be slurped. For large files, it's better | |
718 | to loop: | |
719 | ||
720 | while (<FILE>) { | |
721 | push(@wanted, $_) if /pattern/; | |
722 | } | |
723 | ||
724 | =item * Avoid unnecessary quotes and stringification | |
725 | ||
726 | Don't quote large strings unless absolutely necessary: | |
727 | ||
728 | my $copy = "$large_string"; | |
729 | ||
730 | makes 2 copies of $large_string (one for $copy and another for the | |
731 | quotes), whereas | |
732 | ||
733 | my $copy = $large_string; | |
734 | ||
735 | only makes one copy. | |
736 | ||
737 | Ditto for stringifying large arrays: | |
738 | ||
739 | { | |
740 | local $, = "\n"; | |
741 | print @big_array; | |
742 | } | |
743 | ||
744 | is much more memory-efficient than either | |
745 | ||
746 | print join "\n", @big_array; | |
747 | ||
748 | or | |
749 | ||
750 | { | |
751 | local $" = "\n"; | |
752 | print "@big_array"; | |
753 | } | |
754 | ||
755 | ||
756 | =item * Pass by reference | |
757 | ||
758 | Pass arrays and hashes by reference, not by value. For one thing, it's | |
759 | the only way to pass multiple lists or hashes (or both) in a single | |
760 | call/return. It also avoids creating a copy of all the contents. This | |
761 | requires some judgement, however, because any changes will be propagated | |
762 | back to the original data. If you really want to mangle (er, modify) a | |
763 | copy, you'll have to sacrifice the memory needed to make one. | |
764 | ||
765 | =item * Tie large variables to disk. | |
766 | ||
767 | For "big" data stores (i.e. ones that exceed available memory) consider | |
768 | using one of the DB modules to store it on disk instead of in RAM. This | |
769 | will incur a penalty in access time, but that's probably better than | |
770 | causing your hard disk to thrash due to massive swapping. | |
771 | ||
772 | =back | |
773 | ||
774 | =head2 Is it safe to return a reference to local or lexical data? | |
775 | ||
776 | Yes. Perl's garbage collection system takes care of this so | |
777 | everything works out right. | |
778 | ||
779 | sub makeone { | |
780 | my @a = ( 1 .. 10 ); | |
781 | return \@a; | |
782 | } | |
783 | ||
784 | for ( 1 .. 10 ) { | |
785 | push @many, makeone(); | |
786 | } | |
787 | ||
788 | print $many[4][5], "\n"; | |
789 | ||
790 | print "@many\n"; | |
791 | ||
792 | =head2 How can I free an array or hash so my program shrinks? | |
793 | ||
794 | (contributed by Michael Carman) | |
795 | ||
796 | You usually can't. Memory allocated to lexicals (i.e. my() variables) | |
797 | cannot be reclaimed or reused even if they go out of scope. It is | |
798 | reserved in case the variables come back into scope. Memory allocated | |
799 | to global variables can be reused (within your program) by using | |
800 | undef() and/or delete(). | |
801 | ||
802 | On most operating systems, memory allocated to a program can never be | |
803 | returned to the system. That's why long-running programs sometimes re- | |
804 | exec themselves. Some operating systems (notably, systems that use | |
805 | mmap(2) for allocating large chunks of memory) can reclaim memory that | |
806 | is no longer used, but on such systems, perl must be configured and | |
807 | compiled to use the OS's malloc, not perl's. | |
808 | ||
809 | In general, memory allocation and de-allocation isn't something you can | |
810 | or should be worrying about much in Perl. | |
811 | ||
812 | See also "How can I make my Perl program take less memory?" | |
813 | ||
814 | =head2 How can I make my CGI script more efficient? | |
815 | ||
816 | Beyond the normal measures described to make general Perl programs | |
817 | faster or smaller, a CGI program has additional issues. It may be run | |
818 | several times per second. Given that each time it runs it will need | |
819 | to be re-compiled and will often allocate a megabyte or more of system | |
820 | memory, this can be a killer. Compiling into C B<isn't going to help | |
821 | you> because the process start-up overhead is where the bottleneck is. | |
822 | ||
823 | There are two popular ways to avoid this overhead. One solution | |
824 | involves running the Apache HTTP server (available from | |
825 | http://www.apache.org/ ) with either of the mod_perl or mod_fastcgi | |
826 | plugin modules. | |
827 | ||
828 | With mod_perl and the Apache::Registry module (distributed with | |
829 | mod_perl), httpd will run with an embedded Perl interpreter which | |
830 | pre-compiles your script and then executes it within the same address | |
831 | space without forking. The Apache extension also gives Perl access to | |
832 | the internal server API, so modules written in Perl can do just about | |
833 | anything a module written in C can. For more on mod_perl, see | |
834 | http://perl.apache.org/ | |
835 | ||
836 | With the FCGI module (from CPAN) and the mod_fastcgi | |
837 | module (available from http://www.fastcgi.com/ ) each of your Perl | |
838 | programs becomes a permanent CGI daemon process. | |
839 | ||
840 | Both of these solutions can have far-reaching effects on your system | |
841 | and on the way you write your CGI programs, so investigate them with | |
842 | care. | |
843 | ||
844 | See http://www.cpan.org/modules/by-category/15_World_Wide_Web_HTML_HTTP_CGI/ . | |
845 | ||
846 | =head2 How can I hide the source for my Perl program? | |
847 | ||
848 | Delete it. :-) Seriously, there are a number of (mostly | |
849 | unsatisfactory) solutions with varying levels of "security". | |
850 | ||
851 | First of all, however, you I<can't> take away read permission, because | |
852 | the source code has to be readable in order to be compiled and | |
853 | interpreted. (That doesn't mean that a CGI script's source is | |
854 | readable by people on the web, though--only by people with access to | |
855 | the filesystem.) So you have to leave the permissions at the socially | |
856 | friendly 0755 level. | |
857 | ||
858 | Some people regard this as a security problem. If your program does | |
859 | insecure things and relies on people not knowing how to exploit those | |
860 | insecurities, it is not secure. It is often possible for someone to | |
861 | determine the insecure things and exploit them without viewing the | |
862 | source. Security through obscurity, the name for hiding your bugs | |
863 | instead of fixing them, is little security indeed. | |
864 | ||
865 | You can try using encryption via source filters (Starting from Perl | |
866 | 5.8 the Filter::Simple and Filter::Util::Call modules are included in | |
867 | the standard distribution), but any decent programmer will be able to | |
868 | decrypt it. You can try using the byte code compiler and interpreter | |
869 | described later in L<perlfaq3>, but the curious might still be able to | |
870 | de-compile it. You can try using the native-code compiler described | |
871 | later, but crackers might be able to disassemble it. These pose | |
872 | varying degrees of difficulty to people wanting to get at your code, | |
873 | but none can definitively conceal it (true of every language, not just | |
874 | Perl). | |
875 | ||
876 | It is very easy to recover the source of Perl programs. You simply | |
877 | feed the program to the perl interpreter and use the modules in | |
878 | the B:: hierarchy. The B::Deparse module should be able to | |
879 | defeat most attempts to hide source. Again, this is not | |
880 | unique to Perl. | |
881 | ||
882 | If you're concerned about people profiting from your code, then the | |
883 | bottom line is that nothing but a restrictive license will give you | |
884 | legal security. License your software and pepper it with threatening | |
885 | statements like "This is unpublished proprietary software of XYZ Corp. | |
886 | Your access to it does not give you permission to use it blah blah | |
887 | blah." We are not lawyers, of course, so you should see a lawyer if | |
888 | you want to be sure your license's wording will stand up in court. | |
889 | ||
890 | =head2 How can I compile my Perl program into byte code or C? | |
891 | ||
892 | (contributed by brian d foy) | |
893 | ||
894 | In general, you can't do this. There are some things that may work | |
895 | for your situation though. People usually ask this question | |
896 | because they want to distribute their works without giving away | |
897 | the source code, and most solutions trade disk space for convenience. | |
898 | You probably won't see much of a speed increase either, since most | |
899 | solutions simply bundle a Perl interpreter in the final product | |
900 | (but see L<How can I make my Perl program run faster?>). | |
901 | ||
902 | The Perl Archive Toolkit ( http://par.perl.org/ ) is Perl's | |
903 | analog to Java's JAR. It's freely available and on CPAN ( | |
904 | http://search.cpan.org/dist/PAR/ ). | |
905 | ||
906 | There are also some commercial products that may work for you, although | |
907 | you have to buy a license for them. | |
908 | ||
909 | The Perl Dev Kit ( http://www.activestate.com/Products/Perl_Dev_Kit/ ) | |
910 | from ActiveState can "Turn your Perl programs into ready-to-run | |
911 | executables for HP-UX, Linux, Solaris and Windows." | |
912 | ||
913 | Perl2Exe ( http://www.indigostar.com/perl2exe.htm ) is a command line | |
914 | program for converting perl scripts to executable files. It targets both | |
23bec515 | 915 | Windows and Unix platforms. |
589a5df2 | 916 | |
917 | =head2 How can I get C<#!perl> to work on [MS-DOS,NT,...]? | |
918 | ||
919 | For OS/2 just use | |
920 | ||
921 | extproc perl -S -your_switches | |
922 | ||
923 | as the first line in C<*.cmd> file (C<-S> due to a bug in cmd.exe's | |
924 | "extproc" handling). For DOS one should first invent a corresponding | |
925 | batch file and codify it in C<ALTERNATE_SHEBANG> (see the | |
926 | F<dosish.h> file in the source distribution for more information). | |
927 | ||
928 | The Win95/NT installation, when using the ActiveState port of Perl, | |
929 | will modify the Registry to associate the C<.pl> extension with the | |
930 | perl interpreter. If you install another port, perhaps even building | |
931 | your own Win95/NT Perl from the standard sources by using a Windows port | |
932 | of gcc (e.g., with cygwin or mingw32), then you'll have to modify | |
933 | the Registry yourself. In addition to associating C<.pl> with the | |
934 | interpreter, NT people can use: C<SET PATHEXT=%PATHEXT%;.PL> to let them | |
935 | run the program C<install-linux.pl> merely by typing C<install-linux>. | |
936 | ||
937 | Under "Classic" MacOS, a perl program will have the appropriate Creator and | |
938 | Type, so that double-clicking them will invoke the MacPerl application. | |
939 | Under Mac OS X, clickable apps can be made from any C<#!> script using Wil | |
940 | Sanchez' DropScript utility: http://www.wsanchez.net/software/ . | |
941 | ||
942 | I<IMPORTANT!>: Whatever you do, PLEASE don't get frustrated, and just | |
943 | throw the perl interpreter into your cgi-bin directory, in order to | |
944 | get your programs working for a web server. This is an EXTREMELY big | |
945 | security risk. Take the time to figure out how to do it correctly. | |
946 | ||
947 | =head2 Can I write useful Perl programs on the command line? | |
948 | ||
949 | Yes. Read L<perlrun> for more information. Some examples follow. | |
950 | (These assume standard Unix shell quoting rules.) | |
951 | ||
952 | # sum first and last fields | |
953 | perl -lane 'print $F[0] + $F[-1]' * | |
954 | ||
955 | # identify text files | |
956 | perl -le 'for(@ARGV) {print if -f && -T _}' * | |
957 | ||
958 | # remove (most) comments from C program | |
959 | perl -0777 -pe 's{/\*.*?\*/}{}gs' foo.c | |
960 | ||
961 | # make file a month younger than today, defeating reaper daemons | |
962 | perl -e '$X=24*60*60; utime(time(),time() + 30 * $X,@ARGV)' * | |
963 | ||
964 | # find first unused uid | |
965 | perl -le '$i++ while getpwuid($i); print $i' | |
966 | ||
967 | # display reasonable manpath | |
968 | echo $PATH | perl -nl -072 -e ' | |
969 | s![^/+]*$!man!&&-d&&!$s{$_}++&&push@m,$_;END{print"@m"}' | |
970 | ||
971 | OK, the last one was actually an Obfuscated Perl Contest entry. :-) | |
972 | ||
973 | =head2 Why don't Perl one-liners work on my DOS/Mac/VMS system? | |
974 | ||
975 | The problem is usually that the command interpreters on those systems | |
976 | have rather different ideas about quoting than the Unix shells under | |
977 | which the one-liners were created. On some systems, you may have to | |
978 | change single-quotes to double ones, which you must I<NOT> do on Unix | |
979 | or Plan9 systems. You might also have to change a single % to a %%. | |
980 | ||
981 | For example: | |
982 | ||
983 | # Unix (including Mac OS X) | |
984 | perl -e 'print "Hello world\n"' | |
985 | ||
986 | # DOS, etc. | |
987 | perl -e "print \"Hello world\n\"" | |
988 | ||
989 | # Mac Classic | |
990 | print "Hello world\n" | |
991 | (then Run "Myscript" or Shift-Command-R) | |
992 | ||
993 | # MPW | |
994 | perl -e 'print "Hello world\n"' | |
995 | ||
996 | # VMS | |
997 | perl -e "print ""Hello world\n""" | |
998 | ||
999 | The problem is that none of these examples are reliable: they depend on the | |
1000 | command interpreter. Under Unix, the first two often work. Under DOS, | |
1001 | it's entirely possible that neither works. If 4DOS was the command shell, | |
1002 | you'd probably have better luck like this: | |
1003 | ||
1004 | perl -e "print <Ctrl-x>"Hello world\n<Ctrl-x>"" | |
1005 | ||
1006 | Under the Mac, it depends which environment you are using. The MacPerl | |
1007 | shell, or MPW, is much like Unix shells in its support for several | |
1008 | quoting variants, except that it makes free use of the Mac's non-ASCII | |
1009 | characters as control characters. | |
1010 | ||
1011 | Using qq(), q(), and qx(), instead of "double quotes", 'single | |
1012 | quotes', and `backticks`, may make one-liners easier to write. | |
1013 | ||
1014 | There is no general solution to all of this. It is a mess. | |
1015 | ||
1016 | [Some of this answer was contributed by Kenneth Albanowski.] | |
1017 | ||
1018 | =head2 Where can I learn about CGI or Web programming in Perl? | |
1019 | ||
1020 | For modules, get the CGI or LWP modules from CPAN. For textbooks, | |
1021 | see the two especially dedicated to web stuff in the question on | |
1022 | books. For problems and questions related to the web, like "Why | |
1023 | do I get 500 Errors" or "Why doesn't it run from the browser right | |
1024 | when it runs fine on the command line", see the troubleshooting | |
1025 | guides and references in L<perlfaq9> or in the CGI MetaFAQ: | |
1026 | ||
1027 | http://www.perl.org/CGI_MetaFAQ.html | |
1028 | ||
1029 | =head2 Where can I learn about object-oriented Perl programming? | |
1030 | ||
1031 | A good place to start is L<perltoot>, and you can use L<perlobj>, | |
1032 | L<perlboot>, L<perltoot>, L<perltooc>, and L<perlbot> for reference. | |
1033 | ||
1034 | A good book on OO on Perl is the "Object-Oriented Perl" | |
1035 | by Damian Conway from Manning Publications, or "Intermediate Perl" | |
1036 | by Randal Schwartz, brian d foy, and Tom Phoenix from O'Reilly Media. | |
1037 | ||
1038 | =head2 Where can I learn about linking C with Perl? | |
1039 | ||
1040 | If you want to call C from Perl, start with L<perlxstut>, | |
1041 | moving on to L<perlxs>, L<xsubpp>, and L<perlguts>. If you want to | |
1042 | call Perl from C, then read L<perlembed>, L<perlcall>, and | |
1043 | L<perlguts>. Don't forget that you can learn a lot from looking at | |
1044 | how the authors of existing extension modules wrote their code and | |
1045 | solved their problems. | |
1046 | ||
1047 | You might not need all the power of XS. The Inline::C module lets | |
1048 | you put C code directly in your Perl source. It handles all the | |
1049 | magic to make it work. You still have to learn at least some of | |
1050 | the perl API but you won't have to deal with the complexity of the | |
1051 | XS support files. | |
1052 | ||
1053 | =head2 I've read perlembed, perlguts, etc., but I can't embed perl in my C program; what am I doing wrong? | |
1054 | ||
1055 | Download the ExtUtils::Embed kit from CPAN and run `make test'. If | |
1056 | the tests pass, read the pods again and again and again. If they | |
1057 | fail, see L<perlbug> and send a bug report with the output of | |
1058 | C<make test TEST_VERBOSE=1> along with C<perl -V>. | |
1059 | ||
1060 | =head2 When I tried to run my script, I got this message. What does it mean? | |
1061 | ||
1062 | A complete list of Perl's error messages and warnings with explanatory | |
1063 | text can be found in L<perldiag>. You can also use the splain program | |
1064 | (distributed with Perl) to explain the error messages: | |
1065 | ||
1066 | perl program 2>diag.out | |
1067 | splain [-v] [-p] diag.out | |
1068 | ||
1069 | or change your program to explain the messages for you: | |
1070 | ||
1071 | use diagnostics; | |
1072 | ||
1073 | or | |
1074 | ||
1075 | use diagnostics -verbose; | |
1076 | ||
1077 | =head2 What's MakeMaker? | |
1078 | ||
1079 | (contributed by brian d foy) | |
1080 | ||
1081 | The C<ExtUtils::MakeMaker> module, better known simply as "MakeMaker", | |
1082 | turns a Perl script, typically called C<Makefile.PL>, into a Makefile. | |
23bec515 | 1083 | The Unix tool C<make> uses this file to manage dependencies and actions |
589a5df2 | 1084 | to process and install a Perl distribution. |
1085 | ||
589a5df2 | 1086 | =head1 AUTHOR AND COPYRIGHT |
1087 | ||
8d2e243f | 1088 | Copyright (c) 1997-2010 Tom Christiansen, Nathan Torkington, and |
589a5df2 | 1089 | other authors as noted. All rights reserved. |
1090 | ||
1091 | This documentation is free; you can redistribute it and/or modify it | |
1092 | under the same terms as Perl itself. | |
1093 | ||
1094 | Irrespective of its distribution, all code examples here are in the public | |
1095 | domain. You are permitted and encouraged to use this code and any | |
1096 | derivatives thereof in your own programs for fun or for profit as you | |
1097 | see fit. A simple comment in the code giving credit to the FAQ would | |
1098 | be courteous but is not required. |