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 | |
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 | |
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 | ||
55e174a4 | 58 | The Shell.pm module (distributed with Perl) makes Perl try commands |
a05e4845 RGS |
59 | which aren't part of the Perl language as shell commands. perlsh from |
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 | |
70 | that C<CPAN.pm> understands and cna use to re-install every module: | |
71 | ||
72 | $ cpan -a | |
73 | ||
74 | Inside a Perl program, you can use the ExtUtils::Installed module to | |
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 | |
77 | as "Perl" (although you can get those with 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 | |
85 | can use File::Find::Rule. | |
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 | |
197aec24 | 97 | with 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 RGS |
119 | If you cannot read the documentation, the module might not |
120 | have any (in rare cases). | |
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 | |
125 | perl finds it. | |
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 | |
500071f4 RGS |
156 | If you'd like a graphical user interface and you have Tk, you can use |
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 |
500071f4 RGS |
160 | Brocard's Devel::ebug (which you can call with the -D switch as -Debug) |
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 S |
184 | You can also do the profiling and reporting in one step with the C<-p> |
185 | switch to <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 | ||
197aec24 | 227 | The 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 | ||
55e174a4 JH |
234 | Perltidy is a Perl script which indents and reformats Perl scripts |
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 | |
238 | http://perltidy.sourceforge.net | |
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 | ||
6641ed39 JH |
278 | If you're on Unix, you already have an IDE--Unix itself. The UNIX |
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 | |
ac1094a1 JH |
310 | =item Open Perl IDE |
311 | ||
b68463f7 RGS |
312 | http://open-perl-ide.sourceforge.net/ |
313 | ||
ac1094a1 JH |
314 | Open Perl IDE is an integrated development environment for writing |
315 | and debugging Perl scripts with ActiveState's ActivePerl distribution | |
316 | under Windows 95/98/NT/2000. | |
317 | ||
28b41a80 RGS |
318 | =item OptiPerl |
319 | ||
b68463f7 RGS |
320 | http://www.optiperl.com/ |
321 | ||
322 | OptiPerl is a Windows IDE with simulated CGI environment, including | |
323 | debugger and syntax highlighting editor. | |
28b41a80 | 324 | |
109f0441 S |
325 | =item Padre |
326 | ||
327 | http://padre.perlide.org/ | |
328 | ||
329 | Padre is cross-platform IDE for Perl written in Perl using the the wxWidgets | |
330 | to provide a native look and feel. It's open source under the Artistic | |
331 | License. | |
332 | ||
5ca69f12 JH |
333 | =item PerlBuilder |
334 | ||
b68463f7 RGS |
335 | http://www.solutionsoft.com/perl.htm |
336 | ||
109f0441 | 337 | PerlBuilder is an integrated development environment for Windows that |
b68463f7 | 338 | supports Perl development. |
8782d048 | 339 | |
68fbfbd7 JH |
340 | =item visiPerl+ |
341 | ||
b68463f7 RGS |
342 | http://helpconsulting.net/visiperl/ |
343 | ||
ac1094a1 | 344 | From Help Consulting, for Windows. |
68fbfbd7 | 345 | |
28b41a80 RGS |
346 | =item Visual Perl |
347 | ||
b68463f7 RGS |
348 | http://www.activestate.com/Products/Visual_Perl/ |
349 | ||
28b41a80 | 350 | Visual Perl is a Visual Studio.NET plug-in from ActiveState. |
29b1171f | 351 | |
b68463f7 RGS |
352 | =item Zeus |
353 | ||
354 | http://www.zeusedit.com/lookmain.html | |
355 | ||
356 | Zeus for Window is another Win32 multi-language editor/IDE | |
357 | that comes with support for Perl: | |
29b1171f | 358 | |
68fbfbd7 JH |
359 | =back |
360 | ||
b68463f7 RGS |
361 | For editors: if you're on Unix you probably have vi or a vi clone |
362 | already, and possibly an emacs too, so you may not need to download | |
363 | anything. In any emacs the cperl-mode (M-x cperl-mode) gives you | |
364 | perhaps the best available Perl editing mode in any editor. | |
365 | ||
366 | If you are using Windows, you can use any editor that lets you work | |
367 | with plain text, such as NotePad or WordPad. Word processors, such as | |
368 | Microsoft Word or WordPerfect, typically do not work since they insert | |
369 | all sorts of behind-the-scenes information, although some allow you to | |
370 | save files as "Text Only". You can also download text editors designed | |
371 | specifically for programming, such as Textpad ( | |
372 | http://www.textpad.com/ ) and UltraEdit ( http://www.ultraedit.com/ ), | |
373 | among others. | |
374 | ||
375 | If you are using MacOS, the same concerns apply. MacPerl (for Classic | |
376 | environments) comes with a simple editor. Popular external editors are | |
377 | BBEdit ( http://www.bbedit.com/ ) or Alpha ( | |
378 | http://www.his.com/~jguyer/Alpha/Alpha8.html ). MacOS X users can use | |
c195e131 | 379 | Unix editors as well. |
68fbfbd7 JH |
380 | |
381 | =over 4 | |
382 | ||
383 | =item GNU Emacs | |
384 | ||
385 | http://www.gnu.org/software/emacs/windows/ntemacs.html | |
386 | ||
387 | =item MicroEMACS | |
388 | ||
49d635f9 | 389 | http://www.microemacs.de/ |
68fbfbd7 JH |
390 | |
391 | =item XEmacs | |
392 | ||
393 | http://www.xemacs.org/Download/index.html | |
394 | ||
49d635f9 RGS |
395 | =item Jed |
396 | ||
397 | http://space.mit.edu/~davis/jed/ | |
398 | ||
68fbfbd7 JH |
399 | =back |
400 | ||
401 | or a vi clone such as | |
402 | ||
403 | =over 4 | |
404 | ||
405 | =item Elvis | |
406 | ||
407 | ftp://ftp.cs.pdx.edu/pub/elvis/ http://www.fh-wedel.de/elvis/ | |
408 | ||
409 | =item Vile | |
410 | ||
49d635f9 | 411 | http://dickey.his.com/vile/vile.html |
68fbfbd7 JH |
412 | |
413 | =item Vim | |
414 | ||
415 | http://www.vim.org/ | |
416 | ||
68fbfbd7 JH |
417 | =back |
418 | ||
5a13f98a | 419 | For vi lovers in general, Windows or elsewhere: |
f05bbc40 JH |
420 | |
421 | http://www.thomer.com/thomer/vi/vi.html | |
6641ed39 | 422 | |
f224927c | 423 | nvi ( http://www.bostic.com/vi/ , available from CPAN in src/misc/) is |
5a13f98a | 424 | yet another vi clone, unfortunately not available for Windows, but in |
6641ed39 JH |
425 | UNIX platforms you might be interested in trying it out, firstly because |
426 | strictly speaking it is not a vi clone, it is the real vi, or the new | |
427 | incarnation of it, and secondly because you can embed Perl inside it | |
428 | to use Perl as the scripting language. nvi is not alone in this, | |
7c82de66 | 429 | though: at least also vim and vile offer an embedded Perl. |
614a1598 | 430 | |
109f0441 | 431 | The following are Win32 multilanguage editor/IDEs that support Perl: |
68fbfbd7 JH |
432 | |
433 | =over 4 | |
434 | ||
435 | =item Codewright | |
436 | ||
c98c5709 | 437 | http://www.borland.com/codewright/ |
68fbfbd7 JH |
438 | |
439 | =item MultiEdit | |
440 | ||
441 | http://www.MultiEdit.com/ | |
442 | ||
443 | =item SlickEdit | |
444 | ||
445 | http://www.slickedit.com/ | |
446 | ||
109f0441 S |
447 | =item ConTEXT |
448 | ||
449 | http://www.contexteditor.org/ | |
450 | ||
68fbfbd7 | 451 | =back |
8782d048 | 452 | |
6641ed39 JH |
453 | There is also a toyedit Text widget based editor written in Perl |
454 | that is distributed with the Tk module on CPAN. The ptkdb | |
c195e131 | 455 | ( http://ptkdb.sourceforge.net/ ) is a Perl/tk based debugger that |
8782d048 | 456 | acts as a development environment of sorts. Perl Composer |
49d635f9 | 457 | ( http://perlcomposer.sourceforge.net/ ) is an IDE for Perl/Tk |
e083a89c JH |
458 | GUI creation. |
459 | ||
8782d048 | 460 | In addition to an editor/IDE you might be interested in a more |
68fbfbd7 JH |
461 | powerful shell environment for Win32. Your options include |
462 | ||
463 | =over 4 | |
464 | ||
465 | =item Bash | |
466 | ||
1577cd80 | 467 | from the Cygwin package ( http://sources.redhat.com/cygwin/ ) |
68fbfbd7 JH |
468 | |
469 | =item Ksh | |
470 | ||
109f0441 | 471 | from the MKS Toolkit ( http://www.mkssoftware.com/ ), or the Bourne shell of |
1577cd80 | 472 | the U/WIN environment ( http://www.research.att.com/sw/tools/uwin/ ) |
68fbfbd7 JH |
473 | |
474 | =item Tcsh | |
475 | ||
f224927c | 476 | ftp://ftp.astron.com/pub/tcsh/ , see also |
68fbfbd7 JH |
477 | http://www.primate.wisc.edu/software/csh-tcsh-book/ |
478 | ||
479 | =item Zsh | |
480 | ||
ac9dac7f | 481 | http://www.zsh.org/ |
68fbfbd7 JH |
482 | |
483 | =back | |
484 | ||
614a1598 | 485 | MKS and U/WIN are commercial (U/WIN is free for educational and |
109f0441 S |
486 | research purposes), Cygwin is covered by the GNU General Public |
487 | License (but that shouldn't matter for Perl use). The Cygwin, MKS, | |
488 | and U/WIN all contain (in addition to the shells) a comprehensive set | |
489 | of standard UNIX toolkit utilities. | |
8782d048 | 490 | |
5a13f98a JH |
491 | If you're transferring text files between Unix and Windows using FTP |
492 | be sure to transfer them in ASCII mode so the ends of lines are | |
493 | appropriately converted. | |
494 | ||
e083a89c JH |
495 | On Mac OS the MacPerl Application comes with a simple 32k text editor |
496 | that behaves like a rudimentary IDE. In contrast to the MacPerl Application | |
733271b5 | 497 | the MPW Perl tool can make use of the MPW Shell itself as an editor (with |
68fbfbd7 JH |
498 | no 32k limit). |
499 | ||
500 | =over 4 | |
501 | ||
c98c5709 | 502 | =item Affrus |
68fbfbd7 | 503 | |
d7f8936a | 504 | is a full Perl development environment with full debugger support |
7678cced | 505 | ( http://www.latenightsw.com ). |
68fbfbd7 JH |
506 | |
507 | =item Alpha | |
508 | ||
509 | is an editor, written and extensible in Tcl, that nonetheless has | |
733271b5 | 510 | built in support for several popular markup and programming languages |
c98c5709 RGS |
511 | including Perl and HTML ( http://www.his.com/~jguyer/Alpha/Alpha8.html ). |
512 | ||
513 | =item BBEdit and BBEdit Lite | |
514 | ||
515 | are text editors for Mac OS that have a Perl sensitivity mode | |
516 | ( http://web.barebones.com/ ). | |
517 | ||
68fbfbd7 JH |
518 | |
519 | =back | |
520 | ||
68dc0745 | 521 | =head2 Where can I get Perl macros for vi? |
522 | ||
523 | For a complete version of Tom Christiansen's vi configuration file, | |
a93751fa | 524 | see http://www.cpan.org/authors/Tom_Christiansen/scripts/toms.exrc.gz , |
a6dd486b | 525 | the standard benchmark file for vi emulators. The file runs best with nvi, |
5a964f20 | 526 | the current version of vi out of Berkeley, which incidentally can be built |
bfeeaf1b | 527 | with an embedded Perl interpreter--see http://www.cpan.org/src/misc/ . |
68dc0745 | 528 | |
529 | =head2 Where can I get perl-mode for emacs? | |
530 | ||
531 | Since Emacs version 19 patchlevel 22 or so, there have been both a | |
87275199 | 532 | perl-mode.el and support for the Perl debugger built in. These should |
68dc0745 | 533 | come with the standard Emacs 19 distribution. |
534 | ||
87275199 | 535 | In the Perl source directory, you'll find a directory called "emacs", |
68dc0745 | 536 | which contains a cperl-mode that color-codes keywords, provides |
537 | context-sensitive help, and other nifty things. | |
538 | ||
92c2ed05 | 539 | Note that the perl-mode of emacs will have fits with C<"main'foo"> |
d92eb7b0 | 540 | (single quote), and mess up the indentation and highlighting. You |
65acb1b1 | 541 | are probably using C<"main::foo"> in new Perl code anyway, so this |
92c2ed05 | 542 | shouldn't be an issue. |
68dc0745 | 543 | |
544 | =head2 How can I use curses with Perl? | |
545 | ||
546 | The Curses module from CPAN provides a dynamically loadable object | |
5a964f20 | 547 | module interface to a curses library. A small demo can be found at the |
49d635f9 | 548 | directory http://www.cpan.org/authors/Tom_Christiansen/scripts/rep.gz ; |
5a964f20 TC |
549 | this program repeats a command and updates the screen as needed, rendering |
550 | B<rep ps axu> similar to B<top>. | |
68dc0745 | 551 | |
c195e131 RGS |
552 | =head2 How can I write a GUI (X, Tk, Gtk, etc.) in Perl? |
553 | X<GUI> X<Tk> X<Wx> X<WxWidgets> X<Gtk> X<Gtk2> X<CamelBones> X<Qt> | |
68dc0745 | 554 | |
c195e131 | 555 | (contributed by Ben Morrow) |
68dc0745 | 556 | |
c195e131 RGS |
557 | There are a number of modules which let you write GUIs in Perl. Most |
558 | GUI toolkits have a perl interface: an incomplete list follows. | |
559 | ||
560 | =over 4 | |
561 | ||
562 | =item Tk | |
563 | ||
564 | This works under Unix and Windows, and the current version doesn't | |
565 | look half as bad under Windows as it used to. Some of the gui elements | |
566 | still don't 'feel' quite right, though. The interface is very natural | |
567 | and 'perlish', making it easy to use in small scripts that just need a | |
568 | simple gui. It hasn't been updated in a while. | |
569 | ||
570 | =item Wx | |
571 | ||
109f0441 S |
572 | This is a Perl binding for the cross-platform wxWidgets toolkit |
573 | ( http://www.wxwidgets.org ). It works under Unix, Win32 and Mac OS X, | |
c195e131 RGS |
574 | using native widgets (Gtk under Unix). The interface follows the C++ |
575 | interface closely, but the documentation is a little sparse for someone | |
576 | who doesn't know the library, mostly just referring you to the C++ | |
577 | documentation. | |
578 | ||
579 | =item Gtk and Gtk2 | |
580 | ||
109f0441 | 581 | These are Perl bindings for the Gtk toolkit ( http://www.gtk.org ). The |
c195e131 RGS |
582 | interface changed significantly between versions 1 and 2 so they have |
583 | separate Perl modules. It runs under Unix, Win32 and Mac OS X (currently | |
584 | it requires an X server on Mac OS, but a 'native' port is underway), and | |
585 | the widgets look the same on every plaform: i.e., they don't match the | |
586 | native widgets. As with Wx, the Perl bindings follow the C API closely, | |
587 | and the documentation requires you to read the C documentation to | |
588 | understand it. | |
589 | ||
590 | =item Win32::GUI | |
591 | ||
592 | This provides access to most of the Win32 GUI widgets from Perl. | |
593 | Obviously, it only runs under Win32, and uses native widgets. The Perl | |
594 | interface doesn't really follow the C interface: it's been made more | |
595 | Perlish, and the documentation is pretty good. More advanced stuff may | |
596 | require familiarity with the C Win32 APIs, or reference to MSDN. | |
597 | ||
598 | =item CamelBones | |
599 | ||
109f0441 | 600 | CamelBones ( http://camelbones.sourceforge.net ) is a Perl interface to |
c195e131 RGS |
601 | Mac OS X's Cocoa GUI toolkit, and as such can be used to produce native |
602 | GUIs on Mac OS X. It's not on CPAN, as it requires frameworks that | |
603 | CPAN.pm doesn't know how to install, but installation is via the | |
604 | standard OSX package installer. The Perl API is, again, very close to | |
605 | the ObjC API it's wrapping, and the documentation just tells you how to | |
606 | translate from one to the other. | |
607 | ||
608 | =item Qt | |
609 | ||
610 | There is a Perl interface to TrollTech's Qt toolkit, but it does not | |
611 | appear to be maintained. | |
612 | ||
613 | =item Athena | |
614 | ||
615 | Sx is an interface to the Athena widget set which comes with X, but | |
616 | again it appears not to be much used nowadays. | |
617 | ||
618 | =back | |
92c2ed05 | 619 | |
68dc0745 | 620 | =head2 How can I make my Perl program run faster? |
621 | ||
92c2ed05 | 622 | The best way to do this is to come up with a better algorithm. This |
b73a15ae | 623 | can often make a dramatic difference. Jon Bentley's book |
5cd0b561 | 624 | I<Programming Pearls> (that's not a misspelling!) has some good tips |
92c2ed05 GS |
625 | on optimization, too. Advice on benchmarking boils down to: benchmark |
626 | and profile to make sure you're optimizing the right part, look for | |
627 | better algorithms instead of microtuning your code, and when all else | |
57b19278 | 628 | fails consider just buying faster hardware. You will probably want to |
b432a672 AL |
629 | read the answer to the earlier question "How do I profile my Perl |
630 | programs?" if you haven't done so already. | |
68dc0745 | 631 | |
92c2ed05 | 632 | A different approach is to autoload seldom-used Perl code. See the |
68dc0745 | 633 | AutoSplit and AutoLoader modules in the standard distribution for |
634 | that. Or you could locate the bottleneck and think about writing just | |
635 | that part in C, the way we used to take bottlenecks in C code and | |
5cd0b561 RGS |
636 | write them in assembler. Similar to rewriting in C, modules that have |
637 | critical sections can be written in C (for instance, the PDL module | |
638 | from CPAN). | |
639 | ||
640 | If you're currently linking your perl executable to a shared | |
641 | I<libc.so>, you can often gain a 10-25% performance benefit by | |
642 | rebuilding it to link with a static libc.a instead. This will make a | |
643 | bigger perl executable, but your Perl programs (and programmers) may | |
644 | thank you for it. See the F<INSTALL> file in the source distribution | |
645 | for more information. | |
646 | ||
647 | The undump program was an ancient attempt to speed up Perl program by | |
648 | storing the already-compiled form to disk. This is no longer a viable | |
649 | option, as it only worked on a few architectures, and wasn't a good | |
650 | solution anyway. | |
68dc0745 | 651 | |
652 | =head2 How can I make my Perl program take less memory? | |
653 | ||
654 | When it comes to time-space tradeoffs, Perl nearly always prefers to | |
655 | throw memory at a problem. Scalars in Perl use more memory than | |
65acb1b1 | 656 | strings in C, arrays take more than that, and hashes use even more. While |
68dc0745 | 657 | there's still a lot to be done, recent releases have been addressing |
658 | these issues. For example, as of 5.004, duplicate hash keys are | |
659 | shared amongst all hashes using them, so require no reallocation. | |
660 | ||
661 | In some cases, using substr() or vec() to simulate arrays can be | |
662 | highly beneficial. For example, an array of a thousand booleans will | |
663 | take at least 20,000 bytes of space, but it can be turned into one | |
a6dd486b | 664 | 125-byte bit vector--a considerable memory savings. The standard |
68dc0745 | 665 | Tie::SubstrHash module can also help for certain types of data |
666 | structure. If you're working with specialist data structures | |
667 | (matrices, for instance) modules that implement these in C may use | |
668 | less memory than equivalent Perl modules. | |
669 | ||
670 | Another thing to try is learning whether your Perl was compiled with | |
54310121 | 671 | the system malloc or with Perl's builtin malloc. Whichever one it |
68dc0745 | 672 | is, try using the other one and see whether this makes a difference. |
673 | Information about malloc is in the F<INSTALL> file in the source | |
674 | distribution. You can find out whether you are using perl's malloc by | |
675 | typing C<perl -V:usemymalloc>. | |
676 | ||
24f1ba9b JH |
677 | Of course, the best way to save memory is to not do anything to waste |
678 | it in the first place. Good programming practices can go a long way | |
679 | toward this: | |
680 | ||
681 | =over 4 | |
682 | ||
683 | =item * Don't slurp! | |
684 | ||
685 | Don't read an entire file into memory if you can process it line | |
686 | by line. Or more concretely, use a loop like this: | |
687 | ||
688 | # | |
689 | # Good Idea | |
690 | # | |
691 | while (<FILE>) { | |
692 | # ... | |
693 | } | |
694 | ||
695 | instead of this: | |
696 | ||
697 | # | |
698 | # Bad Idea | |
699 | # | |
700 | @data = <FILE>; | |
701 | foreach (@data) { | |
702 | # ... | |
703 | } | |
704 | ||
705 | When the files you're processing are small, it doesn't much matter which | |
706 | way you do it, but it makes a huge difference when they start getting | |
197aec24 | 707 | larger. |
24f1ba9b | 708 | |
bc06af74 JH |
709 | =item * Use map and grep selectively |
710 | ||
711 | Remember that both map and grep expect a LIST argument, so doing this: | |
712 | ||
713 | @wanted = grep {/pattern/} <FILE>; | |
714 | ||
715 | will cause the entire file to be slurped. For large files, it's better | |
716 | to loop: | |
717 | ||
718 | while (<FILE>) { | |
719 | push(@wanted, $_) if /pattern/; | |
720 | } | |
721 | ||
722 | =item * Avoid unnecessary quotes and stringification | |
723 | ||
724 | Don't quote large strings unless absolutely necessary: | |
725 | ||
726 | my $copy = "$large_string"; | |
727 | ||
728 | makes 2 copies of $large_string (one for $copy and another for the | |
729 | quotes), whereas | |
730 | ||
731 | my $copy = $large_string; | |
732 | ||
733 | only makes one copy. | |
734 | ||
735 | Ditto for stringifying large arrays: | |
736 | ||
737 | { | |
738 | local $, = "\n"; | |
739 | print @big_array; | |
740 | } | |
741 | ||
742 | is much more memory-efficient than either | |
743 | ||
744 | print join "\n", @big_array; | |
745 | ||
746 | or | |
747 | ||
748 | { | |
749 | local $" = "\n"; | |
750 | print "@big_array"; | |
751 | } | |
752 | ||
753 | ||
24f1ba9b JH |
754 | =item * Pass by reference |
755 | ||
756 | Pass arrays and hashes by reference, not by value. For one thing, it's | |
757 | the only way to pass multiple lists or hashes (or both) in a single | |
758 | call/return. It also avoids creating a copy of all the contents. This | |
c195e131 | 759 | requires some judgement, however, because any changes will be propagated |
24f1ba9b JH |
760 | back to the original data. If you really want to mangle (er, modify) a |
761 | copy, you'll have to sacrifice the memory needed to make one. | |
762 | ||
763 | =item * Tie large variables to disk. | |
764 | ||
765 | For "big" data stores (i.e. ones that exceed available memory) consider | |
766 | using one of the DB modules to store it on disk instead of in RAM. This | |
ed8cf1fe | 767 | will incur a penalty in access time, but that's probably better than |
24f1ba9b JH |
768 | causing your hard disk to thrash due to massive swapping. |
769 | ||
770 | =back | |
771 | ||
49d635f9 | 772 | =head2 Is it safe to return a reference to local or lexical data? |
68dc0745 | 773 | |
49d635f9 RGS |
774 | Yes. Perl's garbage collection system takes care of this so |
775 | everything works out right. | |
68dc0745 | 776 | |
777 | sub makeone { | |
778 | my @a = ( 1 .. 10 ); | |
779 | return \@a; | |
780 | } | |
781 | ||
197aec24 | 782 | for ( 1 .. 10 ) { |
68dc0745 | 783 | push @many, makeone(); |
784 | } | |
785 | ||
786 | print $many[4][5], "\n"; | |
787 | ||
788 | print "@many\n"; | |
789 | ||
790 | =head2 How can I free an array or hash so my program shrinks? | |
791 | ||
7678cced RGS |
792 | (contributed by Michael Carman) |
793 | ||
794 | You usually can't. Memory allocated to lexicals (i.e. my() variables) | |
795 | cannot be reclaimed or reused even if they go out of scope. It is | |
796 | reserved in case the variables come back into scope. Memory allocated | |
797 | to global variables can be reused (within your program) by using | |
109f0441 | 798 | undef() and/or delete(). |
7678cced RGS |
799 | |
800 | On most operating systems, memory allocated to a program can never be | |
801 | returned to the system. That's why long-running programs sometimes re- | |
802 | exec themselves. Some operating systems (notably, systems that use | |
803 | mmap(2) for allocating large chunks of memory) can reclaim memory that | |
804 | is no longer used, but on such systems, perl must be configured and | |
805 | compiled to use the OS's malloc, not perl's. | |
806 | ||
46fc3d4c | 807 | In general, memory allocation and de-allocation isn't something you can |
7678cced RGS |
808 | or should be worrying about much in Perl. |
809 | ||
810 | See also "How can I make my Perl program take less memory?" | |
68dc0745 | 811 | |
812 | =head2 How can I make my CGI script more efficient? | |
813 | ||
814 | Beyond the normal measures described to make general Perl programs | |
815 | faster or smaller, a CGI program has additional issues. It may be run | |
816 | several times per second. Given that each time it runs it will need | |
46fc3d4c | 817 | to be re-compiled and will often allocate a megabyte or more of system |
68dc0745 | 818 | memory, this can be a killer. Compiling into C B<isn't going to help |
46fc3d4c | 819 | you> because the process start-up overhead is where the bottleneck is. |
68dc0745 | 820 | |
92c2ed05 GS |
821 | There are two popular ways to avoid this overhead. One solution |
822 | involves running the Apache HTTP server (available from | |
f224927c | 823 | http://www.apache.org/ ) with either of the mod_perl or mod_fastcgi |
92c2ed05 GS |
824 | plugin modules. |
825 | ||
826 | With mod_perl and the Apache::Registry module (distributed with | |
827 | mod_perl), httpd will run with an embedded Perl interpreter which | |
828 | pre-compiles your script and then executes it within the same address | |
829 | space without forking. The Apache extension also gives Perl access to | |
830 | the internal server API, so modules written in Perl can do just about | |
831 | anything a module written in C can. For more on mod_perl, see | |
832 | http://perl.apache.org/ | |
833 | ||
65acb1b1 | 834 | With the FCGI module (from CPAN) and the mod_fastcgi |
bfeeaf1b | 835 | module (available from http://www.fastcgi.com/ ) each of your Perl |
87275199 | 836 | programs becomes a permanent CGI daemon process. |
68dc0745 | 837 | |
838 | Both of these solutions can have far-reaching effects on your system | |
87275199 | 839 | and on the way you write your CGI programs, so investigate them with |
68dc0745 | 840 | care. |
841 | ||
a93751fa | 842 | See http://www.cpan.org/modules/by-category/15_World_Wide_Web_HTML_HTTP_CGI/ . |
5a964f20 | 843 | |
68dc0745 | 844 | =head2 How can I hide the source for my Perl program? |
845 | ||
846 | Delete it. :-) Seriously, there are a number of (mostly | |
b432a672 | 847 | unsatisfactory) solutions with varying levels of "security". |
68dc0745 | 848 | |
849 | First of all, however, you I<can't> take away read permission, because | |
850 | the source code has to be readable in order to be compiled and | |
851 | interpreted. (That doesn't mean that a CGI script's source is | |
a6dd486b JB |
852 | readable by people on the web, though--only by people with access to |
853 | the filesystem.) So you have to leave the permissions at the socially | |
92c2ed05 | 854 | friendly 0755 level. |
68dc0745 | 855 | |
856 | Some people regard this as a security problem. If your program does | |
a6dd486b | 857 | insecure things and relies on people not knowing how to exploit those |
68dc0745 | 858 | insecurities, it is not secure. It is often possible for someone to |
859 | determine the insecure things and exploit them without viewing the | |
860 | source. Security through obscurity, the name for hiding your bugs | |
861 | instead of fixing them, is little security indeed. | |
862 | ||
83df6a1d JH |
863 | You can try using encryption via source filters (Starting from Perl |
864 | 5.8 the Filter::Simple and Filter::Util::Call modules are included in | |
865 | the standard distribution), but any decent programmer will be able to | |
866 | decrypt it. You can try using the byte code compiler and interpreter | |
ac9dac7f RGS |
867 | described later in L<perlfaq3>, but the curious might still be able to |
868 | de-compile it. You can try using the native-code compiler described | |
869 | later, but crackers might be able to disassemble it. These pose | |
870 | varying degrees of difficulty to people wanting to get at your code, | |
871 | but none can definitively conceal it (true of every language, not just | |
872 | Perl). | |
68dc0745 | 873 | |
49d635f9 RGS |
874 | It is very easy to recover the source of Perl programs. You simply |
875 | feed the program to the perl interpreter and use the modules in | |
876 | the B:: hierarchy. The B::Deparse module should be able to | |
877 | defeat most attempts to hide source. Again, this is not | |
878 | unique to Perl. | |
879 | ||
68dc0745 | 880 | If you're concerned about people profiting from your code, then the |
d92eb7b0 | 881 | bottom line is that nothing but a restrictive license will give you |
68dc0745 | 882 | legal security. License your software and pepper it with threatening |
b432a672 | 883 | statements like "This is unpublished proprietary software of XYZ Corp. |
68dc0745 | 884 | Your access to it does not give you permission to use it blah blah |
b432a672 | 885 | blah." We are not lawyers, of course, so you should see a lawyer if |
d92eb7b0 | 886 | you want to be sure your license's wording will stand up in court. |
68dc0745 | 887 | |
54310121 | 888 | =head2 How can I compile my Perl program into byte code or C? |
68dc0745 | 889 | |
7678cced RGS |
890 | (contributed by brian d foy) |
891 | ||
892 | In general, you can't do this. There are some things that may work | |
893 | for your situation though. People usually ask this question | |
6670e5e7 | 894 | because they want to distribute their works without giving away |
7678cced RGS |
895 | the source code, and most solutions trade disk space for convenience. |
896 | You probably won't see much of a speed increase either, since most | |
6670e5e7 | 897 | solutions simply bundle a Perl interpreter in the final product |
7678cced RGS |
898 | (but see L<How can I make my Perl program run faster?>). |
899 | ||
ac9dac7f | 900 | The Perl Archive Toolkit ( http://par.perl.org/ ) is Perl's |
9e72e4c6 RGS |
901 | analog to Java's JAR. It's freely available and on CPAN ( |
902 | http://search.cpan.org/dist/PAR/ ). | |
7678cced | 903 | |
9e72e4c6 RGS |
904 | There are also some commercial products that may work for you, although |
905 | you have to buy a license for them. | |
7678cced | 906 | |
9e72e4c6 RGS |
907 | The Perl Dev Kit ( http://www.activestate.com/Products/Perl_Dev_Kit/ ) |
908 | from ActiveState can "Turn your Perl programs into ready-to-run | |
7678cced RGS |
909 | executables for HP-UX, Linux, Solaris and Windows." |
910 | ||
9e72e4c6 RGS |
911 | Perl2Exe ( http://www.indigostar.com/perl2exe.htm ) is a command line |
912 | program for converting perl scripts to executable files. It targets both | |
913 | Windows and unix platforms. | |
5a964f20 | 914 | |
92c2ed05 | 915 | =head2 How can I get C<#!perl> to work on [MS-DOS,NT,...]? |
68dc0745 | 916 | |
917 | For OS/2 just use | |
918 | ||
919 | extproc perl -S -your_switches | |
920 | ||
921 | as the first line in C<*.cmd> file (C<-S> due to a bug in cmd.exe's | |
b432a672 | 922 | "extproc" handling). For DOS one should first invent a corresponding |
fd1adc71 RGS |
923 | batch file and codify it in C<ALTERNATE_SHEBANG> (see the |
924 | F<dosish.h> file in the source distribution for more information). | |
68dc0745 | 925 | |
92c2ed05 GS |
926 | The Win95/NT installation, when using the ActiveState port of Perl, |
927 | will modify the Registry to associate the C<.pl> extension with the | |
d92eb7b0 GS |
928 | perl interpreter. If you install another port, perhaps even building |
929 | your own Win95/NT Perl from the standard sources by using a Windows port | |
d702ae42 | 930 | of gcc (e.g., with cygwin or mingw32), then you'll have to modify |
d92eb7b0 GS |
931 | the Registry yourself. In addition to associating C<.pl> with the |
932 | interpreter, NT people can use: C<SET PATHEXT=%PATHEXT%;.PL> to let them | |
933 | run the program C<install-linux.pl> merely by typing C<install-linux>. | |
68dc0745 | 934 | |
8e30f651 RGS |
935 | Under "Classic" MacOS, a perl program will have the appropriate Creator and |
936 | Type, so that double-clicking them will invoke the MacPerl application. | |
937 | Under Mac OS X, clickable apps can be made from any C<#!> script using Wil | |
938 | Sanchez' DropScript utility: http://www.wsanchez.net/software/ . | |
68dc0745 | 939 | |
940 | I<IMPORTANT!>: Whatever you do, PLEASE don't get frustrated, and just | |
941 | throw the perl interpreter into your cgi-bin directory, in order to | |
87275199 | 942 | get your programs working for a web server. This is an EXTREMELY big |
68dc0745 | 943 | security risk. Take the time to figure out how to do it correctly. |
944 | ||
87275199 | 945 | =head2 Can I write useful Perl programs on the command line? |
68dc0745 | 946 | |
947 | Yes. Read L<perlrun> for more information. Some examples follow. | |
948 | (These assume standard Unix shell quoting rules.) | |
949 | ||
950 | # sum first and last fields | |
5a964f20 | 951 | perl -lane 'print $F[0] + $F[-1]' * |
68dc0745 | 952 | |
953 | # identify text files | |
954 | perl -le 'for(@ARGV) {print if -f && -T _}' * | |
955 | ||
5a964f20 | 956 | # remove (most) comments from C program |
68dc0745 | 957 | perl -0777 -pe 's{/\*.*?\*/}{}gs' foo.c |
958 | ||
959 | # make file a month younger than today, defeating reaper daemons | |
960 | perl -e '$X=24*60*60; utime(time(),time() + 30 * $X,@ARGV)' * | |
961 | ||
962 | # find first unused uid | |
963 | perl -le '$i++ while getpwuid($i); print $i' | |
964 | ||
965 | # display reasonable manpath | |
966 | echo $PATH | perl -nl -072 -e ' | |
967 | s![^/+]*$!man!&&-d&&!$s{$_}++&&push@m,$_;END{print"@m"}' | |
968 | ||
87275199 | 969 | OK, the last one was actually an Obfuscated Perl Contest entry. :-) |
68dc0745 | 970 | |
87275199 | 971 | =head2 Why don't Perl one-liners work on my DOS/Mac/VMS system? |
68dc0745 | 972 | |
973 | The problem is usually that the command interpreters on those systems | |
974 | have rather different ideas about quoting than the Unix shells under | |
975 | which the one-liners were created. On some systems, you may have to | |
976 | change single-quotes to double ones, which you must I<NOT> do on Unix | |
977 | or Plan9 systems. You might also have to change a single % to a %%. | |
978 | ||
979 | For example: | |
980 | ||
e573f903 | 981 | # Unix (including Mac OS X) |
68dc0745 | 982 | perl -e 'print "Hello world\n"' |
983 | ||
46fc3d4c | 984 | # DOS, etc. |
68dc0745 | 985 | perl -e "print \"Hello world\n\"" |
986 | ||
e573f903 | 987 | # Mac Classic |
68dc0745 | 988 | print "Hello world\n" |
989 | (then Run "Myscript" or Shift-Command-R) | |
990 | ||
d2321c93 JH |
991 | # MPW |
992 | perl -e 'print "Hello world\n"' | |
993 | ||
68dc0745 | 994 | # VMS |
995 | perl -e "print ""Hello world\n""" | |
996 | ||
a6dd486b | 997 | The problem is that none of these examples are reliable: they depend on the |
92c2ed05 | 998 | command interpreter. Under Unix, the first two often work. Under DOS, |
a6dd486b | 999 | it's entirely possible that neither works. If 4DOS was the command shell, |
92c2ed05 | 1000 | you'd probably have better luck like this: |
68dc0745 | 1001 | |
1002 | perl -e "print <Ctrl-x>"Hello world\n<Ctrl-x>"" | |
1003 | ||
46fc3d4c | 1004 | Under the Mac, it depends which environment you are using. The MacPerl |
68dc0745 | 1005 | shell, or MPW, is much like Unix shells in its support for several |
46fc3d4c | 1006 | quoting variants, except that it makes free use of the Mac's non-ASCII |
68dc0745 | 1007 | characters as control characters. |
1008 | ||
65acb1b1 TC |
1009 | Using qq(), q(), and qx(), instead of "double quotes", 'single |
1010 | quotes', and `backticks`, may make one-liners easier to write. | |
1011 | ||
d2321c93 | 1012 | There is no general solution to all of this. It is a mess. |
68dc0745 | 1013 | |
1014 | [Some of this answer was contributed by Kenneth Albanowski.] | |
1015 | ||
1016 | =head2 Where can I learn about CGI or Web programming in Perl? | |
1017 | ||
1018 | For modules, get the CGI or LWP modules from CPAN. For textbooks, | |
1019 | see the two especially dedicated to web stuff in the question on | |
b432a672 AL |
1020 | books. For problems and questions related to the web, like "Why |
1021 | do I get 500 Errors" or "Why doesn't it run from the browser right | |
1022 | when it runs fine on the command line", see the troubleshooting | |
8305e449 | 1023 | guides and references in L<perlfaq9> or in the CGI MetaFAQ: |
68dc0745 | 1024 | |
8305e449 | 1025 | http://www.perl.org/CGI_MetaFAQ.html |
0f542199 | 1026 | |
68dc0745 | 1027 | =head2 Where can I learn about object-oriented Perl programming? |
1028 | ||
a6dd486b | 1029 | A good place to start is L<perltoot>, and you can use L<perlobj>, |
06a5f41f | 1030 | L<perlboot>, L<perltoot>, L<perltooc>, and L<perlbot> for reference. |
06a5f41f JH |
1031 | |
1032 | A good book on OO on Perl is the "Object-Oriented Perl" | |
e573f903 | 1033 | by Damian Conway from Manning Publications, or "Intermediate Perl" |
ac9dac7f | 1034 | by Randal Schwartz, brian d foy, and Tom Phoenix from O'Reilly Media. |
68dc0745 | 1035 | |
b68463f7 | 1036 | =head2 Where can I learn about linking C with Perl? |
68dc0745 | 1037 | |
1038 | If you want to call C from Perl, start with L<perlxstut>, | |
1039 | moving on to L<perlxs>, L<xsubpp>, and L<perlguts>. If you want to | |
1040 | call Perl from C, then read L<perlembed>, L<perlcall>, and | |
1041 | L<perlguts>. Don't forget that you can learn a lot from looking at | |
1042 | how the authors of existing extension modules wrote their code and | |
1043 | solved their problems. | |
1044 | ||
b68463f7 RGS |
1045 | You might not need all the power of XS. The Inline::C module lets |
1046 | you put C code directly in your Perl source. It handles all the | |
58103a2e | 1047 | magic to make it work. You still have to learn at least some of |
b68463f7 RGS |
1048 | the perl API but you won't have to deal with the complexity of the |
1049 | XS support files. | |
1050 | ||
7678cced | 1051 | =head2 I've read perlembed, perlguts, etc., but I can't embed perl in my C program; what am I doing wrong? |
68dc0745 | 1052 | |
1053 | Download the ExtUtils::Embed kit from CPAN and run `make test'. If | |
1054 | the tests pass, read the pods again and again and again. If they | |
87275199 | 1055 | fail, see L<perlbug> and send a bug report with the output of |
68dc0745 | 1056 | C<make test TEST_VERBOSE=1> along with C<perl -V>. |
1057 | ||
83ded9ee | 1058 | =head2 When I tried to run my script, I got this message. What does it mean? |
68dc0745 | 1059 | |
87275199 GS |
1060 | A complete list of Perl's error messages and warnings with explanatory |
1061 | text can be found in L<perldiag>. You can also use the splain program | |
1062 | (distributed with Perl) to explain the error messages: | |
68dc0745 | 1063 | |
1064 | perl program 2>diag.out | |
1065 | splain [-v] [-p] diag.out | |
1066 | ||
1067 | or change your program to explain the messages for you: | |
1068 | ||
1069 | use diagnostics; | |
1070 | ||
1071 | or | |
1072 | ||
1073 | use diagnostics -verbose; | |
1074 | ||
1075 | =head2 What's MakeMaker? | |
1076 | ||
ac9dac7f RGS |
1077 | (contributed by brian d foy) |
1078 | ||
1079 | The C<ExtUtils::MakeMaker> module, better known simply as "MakeMaker", | |
1080 | turns a Perl script, typically called C<Makefile.PL>, into a Makefile. | |
1081 | The unix tool C<make> uses this file to manage dependencies and actions | |
1082 | to process and install a Perl distribution. | |
68dc0745 | 1083 | |
500071f4 RGS |
1084 | =head1 REVISION |
1085 | ||
109f0441 | 1086 | Revision: $Revision$ |
500071f4 | 1087 | |
109f0441 | 1088 | Date: $Date$ |
500071f4 RGS |
1089 | |
1090 | See L<perlfaq> for source control details and availability. | |
1091 | ||
68dc0745 | 1092 | =head1 AUTHOR AND COPYRIGHT |
1093 | ||
109f0441 | 1094 | Copyright (c) 1997-2009 Tom Christiansen, Nathan Torkington, and |
7678cced | 1095 | other authors as noted. All rights reserved. |
5a964f20 | 1096 | |
5a7beb56 JH |
1097 | This documentation is free; you can redistribute it and/or modify it |
1098 | under the same terms as Perl itself. | |
c8db1d39 | 1099 | |
87275199 | 1100 | Irrespective of its distribution, all code examples here are in the public |
c8db1d39 TC |
1101 | domain. You are permitted and encouraged to use this code and any |
1102 | derivatives thereof in your own programs for fun or for profit as you | |
1103 | see fit. A simple comment in the code giving credit to the FAQ would | |
1104 | be courteous but is not required. |