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 | ||
c56bc1f6 | 12 | Have you looked at CPAN (see L<perlfaq2>)? The chances are that |
68dc0745 | 13 | someone has already written a module that can solve your problem. |
c56bc1f6 | 14 | Have you read the appropriate manpages? Here's a brief index: |
68dc0745 | 15 | |
a9feb6cb CBW |
16 | =over 4 |
17 | ||
18 | =item Basics | |
19 | ||
c56bc1f6 CBW |
20 | =over 4 |
21 | ||
22 | =item L<perldata> - Perl data types | |
23 | ||
24 | =item L<perlvar> - Perl pre-defined variables | |
25 | ||
26 | =item L<perlsyn> - Perl syntax | |
27 | ||
28 | =item L<perlop> - Perl operators and precedence | |
29 | ||
30 | =item L<perlsub> - Perl subroutines | |
31 | ||
32 | =back | |
33 | ||
a9feb6cb CBW |
34 | |
35 | =item Execution | |
36 | ||
c56bc1f6 CBW |
37 | =over 4 |
38 | ||
39 | =item L<perlrun> - how to execute the Perl interpreter | |
40 | ||
41 | =item L<perldebug> - Perl debugging | |
42 | ||
43 | =back | |
44 | ||
a9feb6cb CBW |
45 | |
46 | =item Functions | |
47 | ||
c56bc1f6 CBW |
48 | =over 4 |
49 | ||
50 | =item L<perlfunc> - Perl builtin functions | |
51 | ||
52 | =back | |
a9feb6cb CBW |
53 | |
54 | =item Objects | |
55 | ||
c56bc1f6 CBW |
56 | =over 4 |
57 | ||
58 | =item L<perlref> - Perl references and nested data structures | |
59 | ||
60 | =item L<perlmod> - Perl modules (packages and symbol tables) | |
61 | ||
62 | =item L<perlobj> - Perl objects | |
63 | ||
64 | =item L<perltie> - how to hide an object class in a simple variable | |
65 | ||
66 | =back | |
67 | ||
a9feb6cb CBW |
68 | |
69 | =item Data Structures | |
70 | ||
c56bc1f6 CBW |
71 | =over 4 |
72 | ||
73 | =item L<perlref> - Perl references and nested data structures | |
74 | ||
75 | =item L<perllol> - Manipulating arrays of arrays in Perl | |
76 | ||
77 | =item L<perldsc> - Perl Data Structures Cookbook | |
78 | ||
79 | =back | |
a9feb6cb CBW |
80 | |
81 | =item Modules | |
82 | ||
c56bc1f6 CBW |
83 | =over 4 |
84 | ||
85 | =item L<perlmod> - Perl modules (packages and symbol tables) | |
86 | ||
87 | =item L<perlmodlib> - constructing new Perl modules and finding existing ones | |
88 | ||
89 | =back | |
90 | ||
a9feb6cb CBW |
91 | |
92 | =item Regexes | |
93 | ||
c56bc1f6 CBW |
94 | =over 4 |
95 | ||
96 | =item L<perlre> - Perl regular expressions | |
97 | ||
98 | =item L<perlfunc> - Perl builtin functions> | |
99 | ||
100 | =item L<perlop> - Perl operators and precedence | |
101 | ||
102 | =item L<perllocale> - Perl locale handling (internationalization and localization) | |
103 | ||
104 | =back | |
105 | ||
a9feb6cb CBW |
106 | |
107 | =item Moving to perl5 | |
108 | ||
c56bc1f6 CBW |
109 | =over 4 |
110 | ||
111 | =item L<perltrap> - Perl traps for the unwary | |
112 | ||
113 | =item L<perl> | |
114 | ||
115 | =back | |
116 | ||
a9feb6cb CBW |
117 | |
118 | =item Linking with C | |
119 | ||
c56bc1f6 CBW |
120 | =over 4 |
121 | ||
122 | =item L<perlxstut> - Tutorial for writing XSUBs | |
123 | ||
124 | =item L<perlxs> - XS language reference manual | |
125 | ||
126 | =item L<perlcall> - Perl calling conventions from C | |
127 | ||
128 | =item L<perlguts> - Introduction to the Perl API | |
129 | ||
130 | =item L<perlembed> - how to embed perl in your C program | |
131 | ||
132 | =back | |
a9feb6cb CBW |
133 | |
134 | =item Various | |
135 | ||
329d453a CBW |
136 | L<http://www.cpan.org/misc/olddoc/FMTEYEWTK.tgz> |
137 | (not a man-page but still useful, a collection of various essays on | |
a9feb6cb CBW |
138 | Perl techniques) |
139 | ||
140 | =back | |
68dc0745 | 141 | |
3958b146 | 142 | A crude table of contents for the Perl manpage set is found in L<perltoc>. |
68dc0745 | 143 | |
144 | =head2 How can I use Perl interactively? | |
145 | ||
146 | The typical approach uses the Perl debugger, described in the | |
a9feb6cb | 147 | L<perldebug(1)> manpage, on an "empty" program, like this: |
68dc0745 | 148 | |
149 | perl -de 42 | |
150 | ||
151 | Now just type in any legal Perl code, and it will be immediately | |
c56bc1f6 | 152 | evaluated. You can also examine the symbol table, get stack |
68dc0745 | 153 | backtraces, check variable values, set breakpoints, and other |
92c2ed05 | 154 | operations typically found in symbolic debuggers. |
68dc0745 | 155 | |
329d453a | 156 | You can also use L<Devel::REPL> which is an interactive shell for Perl, |
c56bc1f6 CBW |
157 | commonly known as a REPL - Read, Evaluate, Print, Loop. It provides |
158 | various handy features. | |
159 | ||
49d635f9 RGS |
160 | =head2 How do I find which modules are installed on my system? |
161 | ||
109f0441 S |
162 | From the command line, you can use the C<cpan> command's C<-l> switch: |
163 | ||
a9feb6cb | 164 | $ cpan -l |
109f0441 S |
165 | |
166 | You can also use C<cpan>'s C<-a> switch to create an autobundle file | |
589a5df2 | 167 | that C<CPAN.pm> understands and can use to re-install every module: |
109f0441 | 168 | |
a9feb6cb | 169 | $ cpan -a |
109f0441 | 170 | |
a9feb6cb | 171 | Inside a Perl program, you can use the L<ExtUtils::Installed> module to |
109f0441 | 172 | show all installed distributions, although it can take awhile to do |
c56bc1f6 | 173 | its magic. The standard library which comes with Perl just shows up |
a9feb6cb | 174 | as "Perl" (although you can get those with L<Module::CoreList>). |
49d635f9 | 175 | |
a9feb6cb | 176 | use ExtUtils::Installed; |
197aec24 | 177 | |
a9feb6cb CBW |
178 | my $inst = ExtUtils::Installed->new(); |
179 | my @modules = $inst->modules(); | |
49d635f9 RGS |
180 | |
181 | If you want a list of all of the Perl module filenames, you | |
a9feb6cb | 182 | can use L<File::Find::Rule>: |
49d635f9 | 183 | |
a9feb6cb | 184 | use File::Find::Rule; |
197aec24 | 185 | |
a9feb6cb CBW |
186 | my @files = File::Find::Rule-> |
187 | extras({follow => 1})-> | |
188 | file()-> | |
189 | name( '*.pm' )-> | |
190 | in( @INC ) | |
191 | ; | |
49d635f9 RGS |
192 | |
193 | If you do not have that module, you can do the same thing | |
a9feb6cb | 194 | with L<File::Find> which is part of the standard library: |
49d635f9 | 195 | |
a9feb6cb CBW |
196 | use File::Find; |
197 | my @files; | |
109f0441 | 198 | |
a9feb6cb CBW |
199 | find( |
200 | { | |
201 | wanted => sub { | |
202 | push @files, $File::Find::fullname | |
203 | if -f $File::Find::fullname && /\.pm$/ | |
204 | }, | |
205 | follow => 1, | |
206 | follow_skip => 2, | |
207 | }, | |
208 | @INC | |
209 | ); | |
49d635f9 | 210 | |
a9feb6cb | 211 | print join "\n", @files; |
197aec24 | 212 | |
761f3ec6 | 213 | If you simply need to check quickly to see if a module is |
c56bc1f6 | 214 | available, you can check for its documentation. If you can |
197aec24 | 215 | read the documentation the module is most likely installed. |
49d635f9 | 216 | If you cannot read the documentation, the module might not |
589a5df2 | 217 | have any (in rare cases): |
49d635f9 | 218 | |
a9feb6cb | 219 | $ perldoc Module::Name |
49d635f9 RGS |
220 | |
221 | You can also try to include the module in a one-liner to see if | |
589a5df2 | 222 | perl finds it: |
49d635f9 | 223 | |
a9feb6cb | 224 | $ perl -MModule::Name -e1 |
197aec24 | 225 | |
c56bc1f6 CBW |
226 | (If you don't receive a "Can't locate ... in @INC" error message, then Perl |
227 | found the module name you asked for.) | |
228 | ||
68dc0745 | 229 | =head2 How do I debug my Perl programs? |
230 | ||
500071f4 RGS |
231 | (contributed by brian d foy) |
232 | ||
233 | Before you do anything else, you can help yourself by ensuring that | |
234 | you let Perl tell you about problem areas in your code. By turning | |
ac9dac7f | 235 | on warnings and strictures, you can head off many problems before |
500071f4 RGS |
236 | they get too big. You can find out more about these in L<strict> |
237 | and L<warnings>. | |
238 | ||
a9feb6cb CBW |
239 | #!/usr/bin/perl |
240 | use strict; | |
241 | use warnings; | |
ac9dac7f | 242 | |
500071f4 RGS |
243 | Beyond that, the simplest debugger is the C<print> function. Use it |
244 | to look at values as you run your program: | |
245 | ||
a9feb6cb | 246 | print STDERR "The value is [$value]\n"; |
68dc0745 | 247 | |
a9feb6cb | 248 | The L<Data::Dumper> module can pretty-print Perl data structures: |
68dc0745 | 249 | |
a9feb6cb CBW |
250 | use Data::Dumper qw( Dumper ); |
251 | print STDERR "The hash is " . Dumper( \%hash ) . "\n"; | |
ac9dac7f | 252 | |
500071f4 RGS |
253 | Perl comes with an interactive debugger, which you can start with the |
254 | C<-d> switch. It's fully explained in L<perldebug>. | |
68dc0745 | 255 | |
a9feb6cb | 256 | If you'd like a graphical user interface and you have L<Tk>, you can use |
500071f4 | 257 | C<ptkdb>. It's on CPAN and available for free. |
68dc0745 | 258 | |
c195e131 | 259 | If you need something much more sophisticated and controllable, Leon |
a9feb6cb | 260 | Brocard's L<Devel::ebug> (which you can call with the C<-D> switch as C<-Debug>) |
500071f4 RGS |
261 | gives you the programmatic hooks into everything you need to write your |
262 | own (without too much pain and suffering). | |
92c2ed05 | 263 | |
500071f4 RGS |
264 | You can also use a commercial debugger such as Affrus (Mac OS X), Komodo |
265 | from Activestate (Windows and Mac OS X), or EPIC (most platforms). | |
68dc0745 | 266 | |
267 | =head2 How do I profile my Perl programs? | |
268 | ||
109f0441 S |
269 | (contributed by brian d foy, updated Fri Jul 25 12:22:26 PDT 2008) |
270 | ||
271 | The C<Devel> namespace has several modules which you can use to | |
c9dab4e9 | 272 | profile your Perl programs. |
92c2ed05 | 273 | |
a9feb6cb | 274 | The L<Devel::NYTProf> (New York Times Profiler) does both statement |
109f0441 S |
275 | and subroutine profiling. It's available from CPAN and you also invoke |
276 | it with the C<-d> switch: | |
92c2ed05 | 277 | |
a9feb6cb | 278 | perl -d:NYTProf some_perl.pl |
92c2ed05 | 279 | |
c9dab4e9 FR |
280 | It creates a database of the profile information that you can turn into |
281 | reports. The C<nytprofhtml> command turns the data into an HTML report | |
a9feb6cb | 282 | similar to the L<Devel::Cover> report: |
92c2ed05 | 283 | |
a9feb6cb | 284 | nytprofhtml |
92c2ed05 | 285 | |
be539103 | 286 | You might also be interested in using the L<Benchmark> to |
109f0441 S |
287 | measure and compare code snippets. |
288 | ||
289 | You can read more about profiling in I<Programming Perl>, chapter 20, | |
290 | or I<Mastering Perl>, chapter 5. | |
291 | ||
292 | L<perldebguts> documents creating a custom debugger if you need to | |
293 | create a special sort of profiler. brian d foy describes the process | |
294 | in I<The Perl Journal>, "Creating a Perl Debugger", | |
c56bc1f6 CBW |
295 | L<http://www.ddj.com/184404522> , and "Profiling in Perl" |
296 | L<http://www.ddj.com/184404580> . | |
109f0441 S |
297 | |
298 | Perl.com has two interesting articles on profiling: "Profiling Perl", | |
c56bc1f6 | 299 | by Simon Cozens, L<http://www.perl.com/lpt/a/850> and "Debugging and |
109f0441 | 300 | Profiling mod_perl Applications", by Frank Wiles, |
c56bc1f6 | 301 | L<http://www.perl.com/pub/a/2006/02/09/debug_mod_perl.html> . |
109f0441 S |
302 | |
303 | Randal L. Schwartz writes about profiling in "Speeding up Your Perl | |
304 | Programs" for I<Unix Review>, | |
c56bc1f6 | 305 | L<http://www.stonehenge.com/merlyn/UnixReview/col49.html> , and "Profiling |
109f0441 | 306 | in Template Toolkit via Overriding" for I<Linux Magazine>, |
c56bc1f6 | 307 | L<http://www.stonehenge.com/merlyn/LinuxMag/col75.html> . |
65acb1b1 | 308 | |
68dc0745 | 309 | =head2 How do I cross-reference my Perl programs? |
310 | ||
a9feb6cb | 311 | The L<B::Xref> module can be used to generate cross-reference reports |
83ded9ee | 312 | for Perl programs. |
68dc0745 | 313 | |
c8db1d39 | 314 | perl -MO=Xref[,OPTIONS] scriptname.plx |
68dc0745 | 315 | |
316 | =head2 Is there a pretty-printer (formatter) for Perl? | |
317 | ||
329d453a CBW |
318 | L<Perl::Tidy> comes with a perl script L<perltidy> which indents and |
319 | reformats Perl scripts to make them easier to read by trying to follow | |
a9feb6cb CBW |
320 | the rules of the L<perlstyle>. If you write Perl, or spend much time reading |
321 | Perl, you will probably find it useful. | |
55e174a4 JH |
322 | |
323 | Of course, if you simply follow the guidelines in L<perlstyle>, | |
c56bc1f6 CBW |
324 | you shouldn't need to reformat. The habit of formatting your code |
325 | as you write it will help prevent bugs. Your editor can and should | |
326 | help you with this. The perl-mode or newer cperl-mode for emacs | |
55e174a4 JH |
327 | can provide remarkable amounts of help with most (but not all) |
328 | code, and even less programmable editors can provide significant | |
c56bc1f6 | 329 | assistance. Tom Christiansen and many other VI users swear by |
55e174a4 | 330 | the following settings in vi and its clones: |
65acb1b1 TC |
331 | |
332 | set ai sw=4 | |
d92eb7b0 | 333 | map! ^O {^M}^[O^T |
65acb1b1 | 334 | |
55e174a4 | 335 | Put that in your F<.exrc> file (replacing the caret characters |
c56bc1f6 | 336 | with control characters) and away you go. In insert mode, ^T is |
ac9dac7f | 337 | for indenting, ^D is for undenting, and ^O is for blockdenting--as |
c56bc1f6 CBW |
338 | it were. A more complete example, with comments, can be found at |
339 | L<http://www.cpan.org/authors/id/TOMC/scripts/toms.exrc.gz> | |
92c2ed05 | 340 | |
65acb1b1 TC |
341 | =head2 Is there an IDE or Windows Perl Editor? |
342 | ||
6641ed39 JH |
343 | Perl programs are just plain text, so any editor will do. |
344 | ||
c56bc1f6 | 345 | If you're on Unix, you already have an IDE--Unix itself. The Unix |
6641ed39 | 346 | philosophy is the philosophy of several small tools that each do one |
c56bc1f6 | 347 | thing and do it well. It's like a carpenter's toolbox. |
6641ed39 | 348 | |
28b41a80 RGS |
349 | If you want an IDE, check the following (in alphabetical order, not |
350 | order of preference): | |
68fbfbd7 JH |
351 | |
352 | =over 4 | |
353 | ||
28b41a80 RGS |
354 | =item Eclipse |
355 | ||
c56bc1f6 | 356 | L<http://e-p-i-c.sf.net/> |
b68463f7 | 357 | |
6670e5e7 | 358 | The Eclipse Perl Integration Project integrates Perl |
28b41a80 RGS |
359 | editing/debugging with Eclipse. |
360 | ||
b68463f7 RGS |
361 | =item Enginsite |
362 | ||
c56bc1f6 | 363 | L<http://www.enginsite.com/> |
b68463f7 RGS |
364 | |
365 | Perl Editor by EngInSite is a complete integrated development | |
366 | environment (IDE) for creating, testing, and debugging Perl scripts; | |
367 | the tool runs on Windows 9x/NT/2000/XP or later. | |
28b41a80 | 368 | |
338a1057 SH |
369 | =item Kephra |
370 | ||
371 | L<http://kephra.sf.net> | |
372 | ||
dd741cc9 SH |
373 | GUI editor written in Perl using wxWidgets and Scintilla with lots of smaller features. |
374 | Aims for a UI based on Perl principles like TIMTOWTDI and "easy things should be easy, | |
375 | hard things should be possible". | |
338a1057 | 376 | |
68fbfbd7 JH |
377 | =item Komodo |
378 | ||
c56bc1f6 | 379 | L<http://www.ActiveState.com/Products/Komodo/> |
b68463f7 | 380 | |
28b41a80 RGS |
381 | ActiveState's cross-platform (as of October 2004, that's Windows, Linux, |
382 | and Solaris), multi-language IDE has Perl support, including a regular expression | |
b68463f7 | 383 | debugger and remote debugging. |
68fbfbd7 | 384 | |
589a5df2 | 385 | =item Notepad++ |
386 | ||
c56bc1f6 | 387 | L<http://notepad-plus.sourceforge.net/> |
589a5df2 | 388 | |
ac1094a1 JH |
389 | =item Open Perl IDE |
390 | ||
c56bc1f6 | 391 | L<http://open-perl-ide.sourceforge.net/> |
b68463f7 | 392 | |
ac1094a1 JH |
393 | Open Perl IDE is an integrated development environment for writing |
394 | and debugging Perl scripts with ActiveState's ActivePerl distribution | |
395 | under Windows 95/98/NT/2000. | |
396 | ||
28b41a80 RGS |
397 | =item OptiPerl |
398 | ||
c56bc1f6 | 399 | L<http://www.optiperl.com/> |
b68463f7 RGS |
400 | |
401 | OptiPerl is a Windows IDE with simulated CGI environment, including | |
761f3ec6 | 402 | debugger and syntax-highlighting editor. |
28b41a80 | 403 | |
109f0441 S |
404 | =item Padre |
405 | ||
c56bc1f6 | 406 | L<http://padre.perlide.org/> |
109f0441 | 407 | |
589a5df2 | 408 | Padre is cross-platform IDE for Perl written in Perl using wxWidgets to provide |
843331c7 CBW |
409 | a native look and feel. It's open source under the Artistic License. It |
410 | is one of the newer Perl IDEs. | |
109f0441 | 411 | |
5ca69f12 JH |
412 | =item PerlBuilder |
413 | ||
c56bc1f6 | 414 | L<http://www.solutionsoft.com/perl.htm> |
b68463f7 | 415 | |
109f0441 | 416 | PerlBuilder is an integrated development environment for Windows that |
b68463f7 | 417 | supports Perl development. |
8782d048 | 418 | |
68fbfbd7 JH |
419 | =item visiPerl+ |
420 | ||
c56bc1f6 | 421 | L<http://helpconsulting.net/visiperl/index.html> |
b68463f7 | 422 | |
ac1094a1 | 423 | From Help Consulting, for Windows. |
68fbfbd7 | 424 | |
28b41a80 RGS |
425 | =item Visual Perl |
426 | ||
c56bc1f6 | 427 | L<http://www.activestate.com/Products/Visual_Perl/> |
b68463f7 | 428 | |
28b41a80 | 429 | Visual Perl is a Visual Studio.NET plug-in from ActiveState. |
29b1171f | 430 | |
b68463f7 RGS |
431 | =item Zeus |
432 | ||
c56bc1f6 | 433 | L<http://www.zeusedit.com/lookmain.html> |
b68463f7 | 434 | |
6ae27647 | 435 | Zeus for Windows is another Win32 multi-language editor/IDE |
761f3ec6 | 436 | that comes with support for Perl. |
29b1171f | 437 | |
68fbfbd7 JH |
438 | =back |
439 | ||
b68463f7 RGS |
440 | For editors: if you're on Unix you probably have vi or a vi clone |
441 | already, and possibly an emacs too, so you may not need to download | |
442 | anything. In any emacs the cperl-mode (M-x cperl-mode) gives you | |
443 | perhaps the best available Perl editing mode in any editor. | |
444 | ||
445 | If you are using Windows, you can use any editor that lets you work | |
589a5df2 | 446 | with plain text, such as NotePad or WordPad. Word processors, such as |
b68463f7 RGS |
447 | Microsoft Word or WordPerfect, typically do not work since they insert |
448 | all sorts of behind-the-scenes information, although some allow you to | |
589a5df2 | 449 | save files as "Text Only". You can also download text editors designed |
450 | specifically for programming, such as Textpad ( | |
c56bc1f6 | 451 | L<http://www.textpad.com/> ) and UltraEdit ( L<http://www.ultraedit.com/> ), |
589a5df2 | 452 | among others. |
453 | ||
454 | If you are using MacOS, the same concerns apply. MacPerl (for Classic | |
455 | environments) comes with a simple editor. Popular external editors are | |
f3dd8566 | 456 | BBEdit ( L<http://www.barebones.com/products/bbedit/> ) or Alpha ( |
c56bc1f6 | 457 | L<http://www.his.com/~jguyer/Alpha/Alpha8.html> ). MacOS X users can use |
589a5df2 | 458 | Unix editors as well. |
459 | ||
460 | =over 4 | |
461 | ||
462 | =item GNU Emacs | |
463 | ||
c56bc1f6 | 464 | L<http://www.gnu.org/software/emacs/windows/ntemacs.html> |
589a5df2 | 465 | |
466 | =item MicroEMACS | |
467 | ||
c56bc1f6 | 468 | L<http://www.microemacs.de/> |
589a5df2 | 469 | |
470 | =item XEmacs | |
471 | ||
c56bc1f6 | 472 | L<http://www.xemacs.org/Download/index.html> |
589a5df2 | 473 | |
474 | =item Jed | |
475 | ||
c56bc1f6 | 476 | L<http://space.mit.edu/~davis/jed/> |
589a5df2 | 477 | |
478 | =back | |
479 | ||
480 | or a vi clone such as | |
481 | ||
482 | =over 4 | |
483 | ||
589a5df2 | 484 | =item Vim |
485 | ||
c56bc1f6 | 486 | L<http://www.vim.org/> |
589a5df2 | 487 | |
8fa77384 | 488 | =item Vile |
589a5df2 | 489 | |
c56bc1f6 | 490 | L<http://dickey.his.com/vile/vile.html> |
589a5df2 | 491 | |
8fa77384 | 492 | =back |
589a5df2 | 493 | |
494 | The following are Win32 multilanguage editor/IDEs that support Perl: | |
495 | ||
496 | =over 4 | |
497 | ||
498 | =item Codewright | |
499 | ||
c56bc1f6 | 500 | L<http://www.borland.com/codewright/> |
589a5df2 | 501 | |
502 | =item MultiEdit | |
503 | ||
c56bc1f6 | 504 | L<http://www.MultiEdit.com/> |
589a5df2 | 505 | |
506 | =item SlickEdit | |
507 | ||
c56bc1f6 | 508 | L<http://www.slickedit.com/> |
589a5df2 | 509 | |
510 | =item ConTEXT | |
511 | ||
c56bc1f6 | 512 | L<http://www.contexteditor.org/> |
589a5df2 | 513 | |
514 | =back | |
515 | ||
516 | There is also a toyedit Text widget based editor written in Perl | |
c56bc1f6 CBW |
517 | that is distributed with the Tk module on CPAN. The ptkdb |
518 | ( L<http://ptkdb.sourceforge.net/> ) is a Perl/Tk-based debugger that | |
519 | acts as a development environment of sorts. Perl Composer | |
520 | ( L<http://perlcomposer.sourceforge.net/> ) is an IDE for Perl/Tk | |
589a5df2 | 521 | GUI creation. |
522 | ||
523 | In addition to an editor/IDE you might be interested in a more | |
c56bc1f6 | 524 | powerful shell environment for Win32. Your options include |
589a5df2 | 525 | |
526 | =over 4 | |
527 | ||
528 | =item Bash | |
529 | ||
c56bc1f6 | 530 | from the Cygwin package ( L<http://sources.redhat.com/cygwin/> ) |
589a5df2 | 531 | |
532 | =item Ksh | |
533 | ||
c56bc1f6 CBW |
534 | from the MKS Toolkit ( L<http://www.mkssoftware.com/> ), or the Bourne shell of |
535 | the U/WIN environment ( L<http://www.research.att.com/sw/tools/uwin/> ) | |
589a5df2 | 536 | |
537 | =item Tcsh | |
538 | ||
c56bc1f6 CBW |
539 | L<ftp://ftp.astron.com/pub/tcsh/> , see also |
540 | L<http://www.primate.wisc.edu/software/csh-tcsh-book/> | |
589a5df2 | 541 | |
542 | =item Zsh | |
543 | ||
c56bc1f6 | 544 | L<http://www.zsh.org/> |
589a5df2 | 545 | |
546 | =back | |
547 | ||
548 | MKS and U/WIN are commercial (U/WIN is free for educational and | |
549 | research purposes), Cygwin is covered by the GNU General Public | |
c56bc1f6 | 550 | License (but that shouldn't matter for Perl use). The Cygwin, MKS, |
589a5df2 | 551 | and U/WIN all contain (in addition to the shells) a comprehensive set |
23bec515 | 552 | of standard Unix toolkit utilities. |
589a5df2 | 553 | |
554 | If you're transferring text files between Unix and Windows using FTP | |
555 | be sure to transfer them in ASCII mode so the ends of lines are | |
556 | appropriately converted. | |
557 | ||
558 | On Mac OS the MacPerl Application comes with a simple 32k text editor | |
c56bc1f6 | 559 | that behaves like a rudimentary IDE. In contrast to the MacPerl Application |
589a5df2 | 560 | the MPW Perl tool can make use of the MPW Shell itself as an editor (with |
561 | no 32k limit). | |
562 | ||
563 | =over 4 | |
564 | ||
565 | =item Affrus | |
566 | ||
567 | is a full Perl development environment with full debugger support | |
c56bc1f6 | 568 | ( L<http://www.latenightsw.com> ). |
589a5df2 | 569 | |
570 | =item Alpha | |
571 | ||
572 | is an editor, written and extensible in Tcl, that nonetheless has | |
761f3ec6 | 573 | built-in support for several popular markup and programming languages, |
c56bc1f6 | 574 | including Perl and HTML ( L<http://www.his.com/~jguyer/Alpha/Alpha8.html> ). |
589a5df2 | 575 | |
f3dd8566 | 576 | =item BBEdit and TextWrangler |
589a5df2 | 577 | |
578 | are text editors for Mac OS that have a Perl sensitivity mode | |
f3dd8566 | 579 | ( L<http://www.barebones.com/> ). |
589a5df2 | 580 | |
581 | =back | |
582 | ||
583 | =head2 Where can I get Perl macros for vi? | |
584 | ||
585 | For a complete version of Tom Christiansen's vi configuration file, | |
c56bc1f6 CBW |
586 | see L<http://www.cpan.org/authors/Tom_Christiansen/scripts/toms.exrc.gz> , |
587 | the standard benchmark file for vi emulators. The file runs best with nvi, | |
589a5df2 | 588 | the current version of vi out of Berkeley, which incidentally can be built |
c56bc1f6 | 589 | with an embedded Perl interpreter--see L<http://www.cpan.org/src/misc/> . |
589a5df2 | 590 | |
d12d61cf | 591 | =head2 Where can I get perl-mode or cperl-mode for emacs? |
592 | X<emacs> | |
589a5df2 | 593 | |
594 | Since Emacs version 19 patchlevel 22 or so, there have been both a | |
c56bc1f6 | 595 | perl-mode.el and support for the Perl debugger built in. These should |
589a5df2 | 596 | come with the standard Emacs 19 distribution. |
597 | ||
589a5df2 | 598 | Note that the perl-mode of emacs will have fits with C<"main'foo"> |
c56bc1f6 | 599 | (single quote), and mess up the indentation and highlighting. You |
589a5df2 | 600 | are probably using C<"main::foo"> in new Perl code anyway, so this |
601 | shouldn't be an issue. | |
602 | ||
c56bc1f6 | 603 | For CPerlMode, see L<http://www.emacswiki.org/cgi-bin/wiki/CPerlMode> |
d12d61cf | 604 | |
589a5df2 | 605 | =head2 How can I use curses with Perl? |
606 | ||
607 | The Curses module from CPAN provides a dynamically loadable object | |
c56bc1f6 CBW |
608 | module interface to a curses library. A small demo can be found at the |
609 | directory L<http://www.cpan.org/authors/Tom_Christiansen/scripts/rep.gz> ; | |
589a5df2 | 610 | this program repeats a command and updates the screen as needed, rendering |
611 | B<rep ps axu> similar to B<top>. | |
612 | ||
613 | =head2 How can I write a GUI (X, Tk, Gtk, etc.) in Perl? | |
614 | X<GUI> X<Tk> X<Wx> X<WxWidgets> X<Gtk> X<Gtk2> X<CamelBones> X<Qt> | |
615 | ||
616 | (contributed by Ben Morrow) | |
617 | ||
618 | There are a number of modules which let you write GUIs in Perl. Most | |
619 | GUI toolkits have a perl interface: an incomplete list follows. | |
620 | ||
621 | =over 4 | |
622 | ||
623 | =item Tk | |
624 | ||
625 | This works under Unix and Windows, and the current version doesn't | |
626 | look half as bad under Windows as it used to. Some of the gui elements | |
627 | still don't 'feel' quite right, though. The interface is very natural | |
628 | and 'perlish', making it easy to use in small scripts that just need a | |
629 | simple gui. It hasn't been updated in a while. | |
630 | ||
631 | =item Wx | |
632 | ||
633 | This is a Perl binding for the cross-platform wxWidgets toolkit | |
c56bc1f6 | 634 | ( L<http://www.wxwidgets.org> ). It works under Unix, Win32 and Mac OS X, |
589a5df2 | 635 | using native widgets (Gtk under Unix). The interface follows the C++ |
636 | interface closely, but the documentation is a little sparse for someone | |
637 | who doesn't know the library, mostly just referring you to the C++ | |
638 | documentation. | |
639 | ||
640 | =item Gtk and Gtk2 | |
641 | ||
c56bc1f6 | 642 | These are Perl bindings for the Gtk toolkit ( L<http://www.gtk.org> ). The |
589a5df2 | 643 | interface changed significantly between versions 1 and 2 so they have |
644 | separate Perl modules. It runs under Unix, Win32 and Mac OS X (currently | |
645 | it requires an X server on Mac OS, but a 'native' port is underway), and | |
c69ca1d4 | 646 | the widgets look the same on every platform: i.e., they don't match the |
589a5df2 | 647 | native widgets. As with Wx, the Perl bindings follow the C API closely, |
648 | and the documentation requires you to read the C documentation to | |
649 | understand it. | |
650 | ||
651 | =item Win32::GUI | |
652 | ||
653 | This provides access to most of the Win32 GUI widgets from Perl. | |
654 | Obviously, it only runs under Win32, and uses native widgets. The Perl | |
655 | interface doesn't really follow the C interface: it's been made more | |
656 | Perlish, and the documentation is pretty good. More advanced stuff may | |
657 | require familiarity with the C Win32 APIs, or reference to MSDN. | |
658 | ||
659 | =item CamelBones | |
660 | ||
c56bc1f6 | 661 | CamelBones ( L<http://camelbones.sourceforge.net> ) is a Perl interface to |
589a5df2 | 662 | Mac OS X's Cocoa GUI toolkit, and as such can be used to produce native |
663 | GUIs on Mac OS X. It's not on CPAN, as it requires frameworks that | |
664 | CPAN.pm doesn't know how to install, but installation is via the | |
665 | standard OSX package installer. The Perl API is, again, very close to | |
666 | the ObjC API it's wrapping, and the documentation just tells you how to | |
667 | translate from one to the other. | |
668 | ||
669 | =item Qt | |
670 | ||
671 | There is a Perl interface to TrollTech's Qt toolkit, but it does not | |
672 | appear to be maintained. | |
673 | ||
674 | =item Athena | |
675 | ||
676 | Sx is an interface to the Athena widget set which comes with X, but | |
677 | again it appears not to be much used nowadays. | |
678 | ||
679 | =back | |
680 | ||
681 | =head2 How can I make my Perl program run faster? | |
682 | ||
c56bc1f6 CBW |
683 | The best way to do this is to come up with a better algorithm. This |
684 | can often make a dramatic difference. Jon Bentley's book | |
589a5df2 | 685 | I<Programming Pearls> (that's not a misspelling!) has some good tips |
c56bc1f6 | 686 | on optimization, too. Advice on benchmarking boils down to: benchmark |
589a5df2 | 687 | and profile to make sure you're optimizing the right part, look for |
688 | better algorithms instead of microtuning your code, and when all else | |
c56bc1f6 | 689 | fails consider just buying faster hardware. You will probably want to |
589a5df2 | 690 | read the answer to the earlier question "How do I profile my Perl |
691 | programs?" if you haven't done so already. | |
692 | ||
c56bc1f6 | 693 | A different approach is to autoload seldom-used Perl code. See the |
589a5df2 | 694 | AutoSplit and AutoLoader modules in the standard distribution for |
c56bc1f6 | 695 | that. Or you could locate the bottleneck and think about writing just |
589a5df2 | 696 | that part in C, the way we used to take bottlenecks in C code and |
c56bc1f6 | 697 | write them in assembler. Similar to rewriting in C, modules that have |
589a5df2 | 698 | critical sections can be written in C (for instance, the PDL module |
699 | from CPAN). | |
700 | ||
701 | If you're currently linking your perl executable to a shared | |
702 | I<libc.so>, you can often gain a 10-25% performance benefit by | |
c56bc1f6 | 703 | rebuilding it to link with a static libc.a instead. This will make a |
589a5df2 | 704 | bigger perl executable, but your Perl programs (and programmers) may |
c56bc1f6 | 705 | thank you for it. See the F<INSTALL> file in the source distribution |
589a5df2 | 706 | for more information. |
707 | ||
708 | The undump program was an ancient attempt to speed up Perl program by | |
c56bc1f6 | 709 | storing the already-compiled form to disk. This is no longer a viable |
589a5df2 | 710 | option, as it only worked on a few architectures, and wasn't a good |
711 | solution anyway. | |
712 | ||
713 | =head2 How can I make my Perl program take less memory? | |
714 | ||
715 | When it comes to time-space tradeoffs, Perl nearly always prefers to | |
c56bc1f6 CBW |
716 | throw memory at a problem. Scalars in Perl use more memory than |
717 | strings in C, arrays take more than that, and hashes use even more. While | |
589a5df2 | 718 | there's still a lot to be done, recent releases have been addressing |
c56bc1f6 | 719 | these issues. For example, as of 5.004, duplicate hash keys are |
589a5df2 | 720 | shared amongst all hashes using them, so require no reallocation. |
721 | ||
722 | In some cases, using substr() or vec() to simulate arrays can be | |
c56bc1f6 | 723 | highly beneficial. For example, an array of a thousand booleans will |
589a5df2 | 724 | take at least 20,000 bytes of space, but it can be turned into one |
c56bc1f6 | 725 | 125-byte bit vector--a considerable memory savings. The standard |
589a5df2 | 726 | Tie::SubstrHash module can also help for certain types of data |
c56bc1f6 | 727 | structure. If you're working with specialist data structures |
589a5df2 | 728 | (matrices, for instance) modules that implement these in C may use |
729 | less memory than equivalent Perl modules. | |
730 | ||
731 | Another thing to try is learning whether your Perl was compiled with | |
c56bc1f6 | 732 | the system malloc or with Perl's builtin malloc. Whichever one it |
589a5df2 | 733 | is, try using the other one and see whether this makes a difference. |
734 | Information about malloc is in the F<INSTALL> file in the source | |
c56bc1f6 | 735 | distribution. You can find out whether you are using perl's malloc by |
589a5df2 | 736 | typing C<perl -V:usemymalloc>. |
737 | ||
738 | Of course, the best way to save memory is to not do anything to waste | |
739 | it in the first place. Good programming practices can go a long way | |
740 | toward this: | |
741 | ||
742 | =over 4 | |
743 | ||
9d055b1a | 744 | =item Don't slurp! |
589a5df2 | 745 | |
746 | Don't read an entire file into memory if you can process it line | |
747 | by line. Or more concretely, use a loop like this: | |
748 | ||
a9feb6cb CBW |
749 | # |
750 | # Good Idea | |
751 | # | |
c56bc1f6 | 752 | while (my $line = <$file_handle>) { |
a9feb6cb CBW |
753 | # ... |
754 | } | |
589a5df2 | 755 | |
756 | instead of this: | |
757 | ||
a9feb6cb CBW |
758 | # |
759 | # Bad Idea | |
760 | # | |
c56bc1f6 | 761 | my @data = <$file_handle>; |
a9feb6cb CBW |
762 | foreach (@data) { |
763 | # ... | |
764 | } | |
589a5df2 | 765 | |
766 | When the files you're processing are small, it doesn't much matter which | |
767 | way you do it, but it makes a huge difference when they start getting | |
768 | larger. | |
769 | ||
9d055b1a | 770 | =item Use map and grep selectively |
589a5df2 | 771 | |
772 | Remember that both map and grep expect a LIST argument, so doing this: | |
773 | ||
c56bc1f6 | 774 | @wanted = grep {/pattern/} <$file_handle>; |
589a5df2 | 775 | |
776 | will cause the entire file to be slurped. For large files, it's better | |
777 | to loop: | |
778 | ||
c56bc1f6 | 779 | while (<$file_handle>) { |
589a5df2 | 780 | push(@wanted, $_) if /pattern/; |
781 | } | |
782 | ||
9d055b1a | 783 | =item Avoid unnecessary quotes and stringification |
589a5df2 | 784 | |
785 | Don't quote large strings unless absolutely necessary: | |
786 | ||
787 | my $copy = "$large_string"; | |
788 | ||
789 | makes 2 copies of $large_string (one for $copy and another for the | |
790 | quotes), whereas | |
791 | ||
792 | my $copy = $large_string; | |
793 | ||
794 | only makes one copy. | |
795 | ||
796 | Ditto for stringifying large arrays: | |
797 | ||
a9feb6cb CBW |
798 | { |
799 | local $, = "\n"; | |
800 | print @big_array; | |
801 | } | |
589a5df2 | 802 | |
803 | is much more memory-efficient than either | |
804 | ||
a9feb6cb | 805 | print join "\n", @big_array; |
589a5df2 | 806 | |
807 | or | |
808 | ||
a9feb6cb CBW |
809 | { |
810 | local $" = "\n"; | |
811 | print "@big_array"; | |
812 | } | |
589a5df2 | 813 | |
814 | ||
9d055b1a | 815 | =item Pass by reference |
589a5df2 | 816 | |
817 | Pass arrays and hashes by reference, not by value. For one thing, it's | |
818 | the only way to pass multiple lists or hashes (or both) in a single | |
819 | call/return. It also avoids creating a copy of all the contents. This | |
820 | requires some judgement, however, because any changes will be propagated | |
821 | back to the original data. If you really want to mangle (er, modify) a | |
822 | copy, you'll have to sacrifice the memory needed to make one. | |
823 | ||
9d055b1a | 824 | =item Tie large variables to disk |
589a5df2 | 825 | |
826 | For "big" data stores (i.e. ones that exceed available memory) consider | |
827 | using one of the DB modules to store it on disk instead of in RAM. This | |
828 | will incur a penalty in access time, but that's probably better than | |
829 | causing your hard disk to thrash due to massive swapping. | |
830 | ||
831 | =back | |
832 | ||
833 | =head2 Is it safe to return a reference to local or lexical data? | |
834 | ||
835 | Yes. Perl's garbage collection system takes care of this so | |
836 | everything works out right. | |
837 | ||
838 | sub makeone { | |
a9feb6cb CBW |
839 | my @a = ( 1 .. 10 ); |
840 | return \@a; | |
589a5df2 | 841 | } |
842 | ||
843 | for ( 1 .. 10 ) { | |
844 | push @many, makeone(); | |
845 | } | |
846 | ||
847 | print $many[4][5], "\n"; | |
848 | ||
849 | print "@many\n"; | |
850 | ||
851 | =head2 How can I free an array or hash so my program shrinks? | |
852 | ||
853 | (contributed by Michael Carman) | |
854 | ||
855 | You usually can't. Memory allocated to lexicals (i.e. my() variables) | |
856 | cannot be reclaimed or reused even if they go out of scope. It is | |
857 | reserved in case the variables come back into scope. Memory allocated | |
858 | to global variables can be reused (within your program) by using | |
859 | undef() and/or delete(). | |
860 | ||
861 | On most operating systems, memory allocated to a program can never be | |
862 | returned to the system. That's why long-running programs sometimes re- | |
863 | exec themselves. Some operating systems (notably, systems that use | |
864 | mmap(2) for allocating large chunks of memory) can reclaim memory that | |
865 | is no longer used, but on such systems, perl must be configured and | |
866 | compiled to use the OS's malloc, not perl's. | |
867 | ||
868 | In general, memory allocation and de-allocation isn't something you can | |
869 | or should be worrying about much in Perl. | |
870 | ||
871 | See also "How can I make my Perl program take less memory?" | |
872 | ||
873 | =head2 How can I make my CGI script more efficient? | |
874 | ||
875 | Beyond the normal measures described to make general Perl programs | |
c56bc1f6 CBW |
876 | faster or smaller, a CGI program has additional issues. It may be run |
877 | several times per second. Given that each time it runs it will need | |
589a5df2 | 878 | to be re-compiled and will often allocate a megabyte or more of system |
c56bc1f6 | 879 | memory, this can be a killer. Compiling into C B<isn't going to help |
589a5df2 | 880 | you> because the process start-up overhead is where the bottleneck is. |
881 | ||
c56bc1f6 | 882 | There are three popular ways to avoid this overhead. One solution |
589a5df2 | 883 | involves running the Apache HTTP server (available from |
c56bc1f6 | 884 | L<http://www.apache.org/> ) with either of the mod_perl or mod_fastcgi |
589a5df2 | 885 | plugin modules. |
886 | ||
887 | With mod_perl and the Apache::Registry module (distributed with | |
888 | mod_perl), httpd will run with an embedded Perl interpreter which | |
889 | pre-compiles your script and then executes it within the same address | |
c56bc1f6 | 890 | space without forking. The Apache extension also gives Perl access to |
589a5df2 | 891 | the internal server API, so modules written in Perl can do just about |
c56bc1f6 CBW |
892 | anything a module written in C can. For more on mod_perl, see |
893 | L<http://perl.apache.org/> | |
589a5df2 | 894 | |
895 | With the FCGI module (from CPAN) and the mod_fastcgi | |
c56bc1f6 | 896 | module (available from L<http://www.fastcgi.com/> ) each of your Perl |
589a5df2 | 897 | programs becomes a permanent CGI daemon process. |
898 | ||
c56bc1f6 CBW |
899 | Finally, L<Plack> is a Perl module and toolkit that contains PSGI middleware, |
900 | helpers and adapters to web servers, allowing you to easily deploy scripts which | |
901 | can continue running, and provides flexibility with regards to which web server | |
902 | you use. It can allow existing CGI scripts to enjoy this flexibility and | |
903 | performance with minimal changes, or can be used along with modern Perl web | |
904 | frameworks to make writing and deploying web services with Perl a breeze. | |
905 | ||
329d453a | 906 | These solutions can have far-reaching effects on your system and on the way you |
c56bc1f6 | 907 | write your CGI programs, so investigate them with care. |
589a5df2 | 908 | |
761f3ec6 | 909 | See also |
c56bc1f6 | 910 | L<http://www.cpan.org/modules/by-category/15_World_Wide_Web_HTML_HTTP_CGI/> . |
589a5df2 | 911 | |
912 | =head2 How can I hide the source for my Perl program? | |
913 | ||
914 | Delete it. :-) Seriously, there are a number of (mostly | |
915 | unsatisfactory) solutions with varying levels of "security". | |
916 | ||
917 | First of all, however, you I<can't> take away read permission, because | |
918 | the source code has to be readable in order to be compiled and | |
c56bc1f6 | 919 | interpreted. (That doesn't mean that a CGI script's source is |
589a5df2 | 920 | readable by people on the web, though--only by people with access to |
921 | the filesystem.) So you have to leave the permissions at the socially | |
922 | friendly 0755 level. | |
923 | ||
c56bc1f6 | 924 | Some people regard this as a security problem. If your program does |
589a5df2 | 925 | insecure things and relies on people not knowing how to exploit those |
c56bc1f6 | 926 | insecurities, it is not secure. It is often possible for someone to |
589a5df2 | 927 | determine the insecure things and exploit them without viewing the |
c56bc1f6 | 928 | source. Security through obscurity, the name for hiding your bugs |
589a5df2 | 929 | instead of fixing them, is little security indeed. |
930 | ||
931 | You can try using encryption via source filters (Starting from Perl | |
932 | 5.8 the Filter::Simple and Filter::Util::Call modules are included in | |
933 | the standard distribution), but any decent programmer will be able to | |
c56bc1f6 | 934 | decrypt it. You can try using the byte code compiler and interpreter |
589a5df2 | 935 | described later in L<perlfaq3>, but the curious might still be able to |
936 | de-compile it. You can try using the native-code compiler described | |
c56bc1f6 | 937 | later, but crackers might be able to disassemble it. These pose |
589a5df2 | 938 | varying degrees of difficulty to people wanting to get at your code, |
939 | but none can definitively conceal it (true of every language, not just | |
940 | Perl). | |
941 | ||
c56bc1f6 | 942 | It is very easy to recover the source of Perl programs. You simply |
589a5df2 | 943 | feed the program to the perl interpreter and use the modules in |
c56bc1f6 CBW |
944 | the B:: hierarchy. The B::Deparse module should be able to |
945 | defeat most attempts to hide source. Again, this is not | |
589a5df2 | 946 | unique to Perl. |
947 | ||
948 | If you're concerned about people profiting from your code, then the | |
949 | bottom line is that nothing but a restrictive license will give you | |
c56bc1f6 | 950 | legal security. License your software and pepper it with threatening |
589a5df2 | 951 | statements like "This is unpublished proprietary software of XYZ Corp. |
952 | Your access to it does not give you permission to use it blah blah | |
953 | blah." We are not lawyers, of course, so you should see a lawyer if | |
954 | you want to be sure your license's wording will stand up in court. | |
955 | ||
956 | =head2 How can I compile my Perl program into byte code or C? | |
957 | ||
958 | (contributed by brian d foy) | |
959 | ||
c56bc1f6 CBW |
960 | In general, you can't do this. There are some things that may work |
961 | for your situation though. People usually ask this question | |
589a5df2 | 962 | because they want to distribute their works without giving away |
963 | the source code, and most solutions trade disk space for convenience. | |
964 | You probably won't see much of a speed increase either, since most | |
965 | solutions simply bundle a Perl interpreter in the final product | |
966 | (but see L<How can I make my Perl program run faster?>). | |
967 | ||
c56bc1f6 CBW |
968 | The Perl Archive Toolkit ( L<http://par.perl.org/> ) is Perl's |
969 | analog to Java's JAR. It's freely available and on CPAN ( | |
970 | L<http://search.cpan.org/dist/PAR/> ). | |
589a5df2 | 971 | |
972 | There are also some commercial products that may work for you, although | |
973 | you have to buy a license for them. | |
974 | ||
c56bc1f6 | 975 | The Perl Dev Kit ( L<http://www.activestate.com/Products/Perl_Dev_Kit/> ) |
589a5df2 | 976 | from ActiveState can "Turn your Perl programs into ready-to-run |
977 | executables for HP-UX, Linux, Solaris and Windows." | |
978 | ||
c56bc1f6 CBW |
979 | Perl2Exe ( L<http://www.indigostar.com/perl2exe.htm> ) is a command line |
980 | program for converting perl scripts to executable files. It targets both | |
23bec515 | 981 | Windows and Unix platforms. |
589a5df2 | 982 | |
983 | =head2 How can I get C<#!perl> to work on [MS-DOS,NT,...]? | |
984 | ||
985 | For OS/2 just use | |
986 | ||
987 | extproc perl -S -your_switches | |
988 | ||
989 | as the first line in C<*.cmd> file (C<-S> due to a bug in cmd.exe's | |
c56bc1f6 | 990 | "extproc" handling). For DOS one should first invent a corresponding |
589a5df2 | 991 | batch file and codify it in C<ALTERNATE_SHEBANG> (see the |
992 | F<dosish.h> file in the source distribution for more information). | |
993 | ||
994 | The Win95/NT installation, when using the ActiveState port of Perl, | |
995 | will modify the Registry to associate the C<.pl> extension with the | |
c56bc1f6 | 996 | perl interpreter. If you install another port, perhaps even building |
589a5df2 | 997 | your own Win95/NT Perl from the standard sources by using a Windows port |
998 | of gcc (e.g., with cygwin or mingw32), then you'll have to modify | |
c56bc1f6 | 999 | the Registry yourself. In addition to associating C<.pl> with the |
589a5df2 | 1000 | interpreter, NT people can use: C<SET PATHEXT=%PATHEXT%;.PL> to let them |
1001 | run the program C<install-linux.pl> merely by typing C<install-linux>. | |
1002 | ||
1003 | Under "Classic" MacOS, a perl program will have the appropriate Creator and | |
1004 | Type, so that double-clicking them will invoke the MacPerl application. | |
1005 | Under Mac OS X, clickable apps can be made from any C<#!> script using Wil | |
c56bc1f6 | 1006 | Sanchez' DropScript utility: L<http://www.wsanchez.net/software/> . |
589a5df2 | 1007 | |
1008 | I<IMPORTANT!>: Whatever you do, PLEASE don't get frustrated, and just | |
1009 | throw the perl interpreter into your cgi-bin directory, in order to | |
c56bc1f6 CBW |
1010 | get your programs working for a web server. This is an EXTREMELY big |
1011 | security risk. Take the time to figure out how to do it correctly. | |
589a5df2 | 1012 | |
1013 | =head2 Can I write useful Perl programs on the command line? | |
1014 | ||
c56bc1f6 | 1015 | Yes. Read L<perlrun> for more information. Some examples follow. |
589a5df2 | 1016 | (These assume standard Unix shell quoting rules.) |
1017 | ||
1018 | # sum first and last fields | |
1019 | perl -lane 'print $F[0] + $F[-1]' * | |
1020 | ||
1021 | # identify text files | |
1022 | perl -le 'for(@ARGV) {print if -f && -T _}' * | |
1023 | ||
1024 | # remove (most) comments from C program | |
1025 | perl -0777 -pe 's{/\*.*?\*/}{}gs' foo.c | |
1026 | ||
1027 | # make file a month younger than today, defeating reaper daemons | |
1028 | perl -e '$X=24*60*60; utime(time(),time() + 30 * $X,@ARGV)' * | |
1029 | ||
1030 | # find first unused uid | |
1031 | perl -le '$i++ while getpwuid($i); print $i' | |
1032 | ||
1033 | # display reasonable manpath | |
1034 | echo $PATH | perl -nl -072 -e ' | |
a9feb6cb | 1035 | s![^/+]*$!man!&&-d&&!$s{$_}++&&push@m,$_;END{print"@m"}' |
589a5df2 | 1036 | |
1037 | OK, the last one was actually an Obfuscated Perl Contest entry. :-) | |
1038 | ||
1039 | =head2 Why don't Perl one-liners work on my DOS/Mac/VMS system? | |
1040 | ||
1041 | The problem is usually that the command interpreters on those systems | |
1042 | have rather different ideas about quoting than the Unix shells under | |
c56bc1f6 | 1043 | which the one-liners were created. On some systems, you may have to |
589a5df2 | 1044 | change single-quotes to double ones, which you must I<NOT> do on Unix |
c56bc1f6 | 1045 | or Plan9 systems. You might also have to change a single % to a %%. |
589a5df2 | 1046 | |
1047 | For example: | |
1048 | ||
1049 | # Unix (including Mac OS X) | |
1050 | perl -e 'print "Hello world\n"' | |
1051 | ||
1052 | # DOS, etc. | |
1053 | perl -e "print \"Hello world\n\"" | |
1054 | ||
1055 | # Mac Classic | |
1056 | print "Hello world\n" | |
1057 | (then Run "Myscript" or Shift-Command-R) | |
1058 | ||
1059 | # MPW | |
1060 | perl -e 'print "Hello world\n"' | |
1061 | ||
1062 | # VMS | |
1063 | perl -e "print ""Hello world\n""" | |
1064 | ||
1065 | The problem is that none of these examples are reliable: they depend on the | |
c56bc1f6 CBW |
1066 | command interpreter. Under Unix, the first two often work. Under DOS, |
1067 | it's entirely possible that neither works. If 4DOS was the command shell, | |
589a5df2 | 1068 | you'd probably have better luck like this: |
1069 | ||
1070 | perl -e "print <Ctrl-x>"Hello world\n<Ctrl-x>"" | |
1071 | ||
c56bc1f6 | 1072 | Under the Mac, it depends which environment you are using. The MacPerl |
589a5df2 | 1073 | shell, or MPW, is much like Unix shells in its support for several |
1074 | quoting variants, except that it makes free use of the Mac's non-ASCII | |
1075 | characters as control characters. | |
1076 | ||
1077 | Using qq(), q(), and qx(), instead of "double quotes", 'single | |
1078 | quotes', and `backticks`, may make one-liners easier to write. | |
1079 | ||
c56bc1f6 | 1080 | There is no general solution to all of this. It is a mess. |
589a5df2 | 1081 | |
1082 | [Some of this answer was contributed by Kenneth Albanowski.] | |
1083 | ||
1084 | =head2 Where can I learn about CGI or Web programming in Perl? | |
1085 | ||
c56bc1f6 | 1086 | For modules, get the CGI or LWP modules from CPAN. For textbooks, |
589a5df2 | 1087 | see the two especially dedicated to web stuff in the question on |
c56bc1f6 | 1088 | books. For problems and questions related to the web, like "Why |
589a5df2 | 1089 | do I get 500 Errors" or "Why doesn't it run from the browser right |
1090 | when it runs fine on the command line", see the troubleshooting | |
1091 | guides and references in L<perlfaq9> or in the CGI MetaFAQ: | |
1092 | ||
c56bc1f6 CBW |
1093 | L<http://www.perl.org/CGI_MetaFAQ.html> |
1094 | ||
1095 | Looking in to L<Plack> and modern Perl web frameworks is highly recommended, | |
1096 | though; web programming in Perl has evolved a long way from the old days of | |
1097 | simple CGI scripts. | |
589a5df2 | 1098 | |
1099 | =head2 Where can I learn about object-oriented Perl programming? | |
1100 | ||
dd741cc9 SH |
1101 | A good place to start is L<perlootut>, and you can use L<perlobj> for |
1102 | reference. | |
589a5df2 | 1103 | |
1104 | A good book on OO on Perl is the "Object-Oriented Perl" | |
1105 | by Damian Conway from Manning Publications, or "Intermediate Perl" | |
1106 | by Randal Schwartz, brian d foy, and Tom Phoenix from O'Reilly Media. | |
1107 | ||
1108 | =head2 Where can I learn about linking C with Perl? | |
1109 | ||
1110 | If you want to call C from Perl, start with L<perlxstut>, | |
c56bc1f6 | 1111 | moving on to L<perlxs>, L<xsubpp>, and L<perlguts>. If you want to |
589a5df2 | 1112 | call Perl from C, then read L<perlembed>, L<perlcall>, and |
c56bc1f6 | 1113 | L<perlguts>. Don't forget that you can learn a lot from looking at |
589a5df2 | 1114 | how the authors of existing extension modules wrote their code and |
1115 | solved their problems. | |
1116 | ||
1117 | You might not need all the power of XS. The Inline::C module lets | |
1118 | you put C code directly in your Perl source. It handles all the | |
1119 | magic to make it work. You still have to learn at least some of | |
1120 | the perl API but you won't have to deal with the complexity of the | |
1121 | XS support files. | |
1122 | ||
1123 | =head2 I've read perlembed, perlguts, etc., but I can't embed perl in my C program; what am I doing wrong? | |
1124 | ||
c56bc1f6 CBW |
1125 | Download the ExtUtils::Embed kit from CPAN and run `make test'. If |
1126 | the tests pass, read the pods again and again and again. If they | |
589a5df2 | 1127 | fail, see L<perlbug> and send a bug report with the output of |
1128 | C<make test TEST_VERBOSE=1> along with C<perl -V>. | |
1129 | ||
1130 | =head2 When I tried to run my script, I got this message. What does it mean? | |
1131 | ||
1132 | A complete list of Perl's error messages and warnings with explanatory | |
1133 | text can be found in L<perldiag>. You can also use the splain program | |
1134 | (distributed with Perl) to explain the error messages: | |
1135 | ||
1136 | perl program 2>diag.out | |
1137 | splain [-v] [-p] diag.out | |
1138 | ||
1139 | or change your program to explain the messages for you: | |
1140 | ||
1141 | use diagnostics; | |
1142 | ||
1143 | or | |
1144 | ||
1145 | use diagnostics -verbose; | |
1146 | ||
1147 | =head2 What's MakeMaker? | |
1148 | ||
1149 | (contributed by brian d foy) | |
1150 | ||
a9feb6cb | 1151 | The L<ExtUtils::MakeMaker> module, better known simply as "MakeMaker", |
589a5df2 | 1152 | turns a Perl script, typically called C<Makefile.PL>, into a Makefile. |
23bec515 | 1153 | The Unix tool C<make> uses this file to manage dependencies and actions |
589a5df2 | 1154 | to process and install a Perl distribution. |
1155 | ||
589a5df2 | 1156 | =head1 AUTHOR AND COPYRIGHT |
1157 | ||
8d2e243f | 1158 | Copyright (c) 1997-2010 Tom Christiansen, Nathan Torkington, and |
589a5df2 | 1159 | other authors as noted. All rights reserved. |
1160 | ||
1161 | This documentation is free; you can redistribute it and/or modify it | |
1162 | under the same terms as Perl itself. | |
1163 | ||
1164 | Irrespective of its distribution, all code examples here are in the public | |
c56bc1f6 | 1165 | domain. You are permitted and encouraged to use this code and any |
589a5df2 | 1166 | derivatives thereof in your own programs for fun or for profit as you |
c56bc1f6 | 1167 | see fit. A simple comment in the code giving credit to the FAQ would |
589a5df2 | 1168 | be courteous but is not required. |