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129 | .\" ======================================================================== | |
130 | .\" | |
131 | .IX Title "PERLFAQ3 1" | |
132 | .TH PERLFAQ3 1 "2002-06-08" "perl v5.8.0" "Perl Programmers Reference Guide" | |
133 | .SH "NAME" | |
134 | perlfaq3 \- Programming Tools ($Revision: 1.22 $, $Date: 2002/05/06 13:11:13 $) | |
135 | .SH "DESCRIPTION" | |
136 | .IX Header "DESCRIPTION" | |
137 | This section of the \s-1FAQ\s0 answers questions related to programmer tools | |
138 | and programming support. | |
139 | .Sh "How do I do (anything)?" | |
140 | .IX Subsection "How do I do (anything)?" | |
141 | Have you looked at \s-1CPAN\s0 (see perlfaq2)? The chances are that | |
142 | someone has already written a module that can solve your problem. | |
143 | Have you read the appropriate manpages? Here's a brief index: | |
144 | .PP | |
145 | .Vb 12 | |
146 | \& Basics perldata, perlvar, perlsyn, perlop, perlsub | |
147 | \& Execution perlrun, perldebug | |
148 | \& Functions perlfunc | |
149 | \& Objects perlref, perlmod, perlobj, perltie | |
150 | \& Data Structures perlref, perllol, perldsc | |
151 | \& Modules perlmod, perlmodlib, perlsub | |
152 | \& Regexes perlre, perlfunc, perlop, perllocale | |
153 | \& Moving to perl5 perltrap, perl | |
154 | \& Linking w/C perlxstut, perlxs, perlcall, perlguts, perlembed | |
155 | \& Various http://www.cpan.org/misc/olddoc/FMTEYEWTK.tgz | |
156 | \& (not a man-page but still useful, a collection | |
157 | \& of various essays on Perl techniques) | |
158 | .Ve | |
159 | .PP | |
160 | A crude table of contents for the Perl manpage set is found in perltoc. | |
161 | .Sh "How can I use Perl interactively?" | |
162 | .IX Subsection "How can I use Perl interactively?" | |
163 | The typical approach uses the Perl debugger, described in the | |
164 | \&\fIperldebug\fR\|(1) manpage, on an ``empty'' program, like this: | |
165 | .PP | |
166 | .Vb 1 | |
167 | \& perl -de 42 | |
168 | .Ve | |
169 | .PP | |
170 | Now just type in any legal Perl code, and it will be immediately | |
171 | evaluated. You can also examine the symbol table, get stack | |
172 | backtraces, check variable values, set breakpoints, and other | |
173 | operations typically found in symbolic debuggers. | |
174 | .Sh "Is there a Perl shell?" | |
175 | .IX Subsection "Is there a Perl shell?" | |
176 | In general, not yet. There is psh available at | |
177 | .PP | |
178 | .Vb 1 | |
179 | \& http://www.focusresearch.com/gregor/psh | |
180 | .Ve | |
181 | .PP | |
182 | Which includes the following description: | |
183 | .PP | |
184 | .Vb 5 | |
185 | \& The Perl Shell is a shell that combines the interactive nature | |
186 | \& of a Unix shell with the power of Perl. The goal is to eventually | |
187 | \& have a full featured shell that behaves as expected for normal | |
188 | \& shell activity. But, the Perl Shell will use Perl syntax and | |
189 | \& functionality for control-flow statements and other things. | |
190 | .Ve | |
191 | .PP | |
192 | The Shell.pm module (distributed with Perl) makes Perl try commands | |
193 | which aren't part of the Perl language as shell commands. perlsh | |
194 | from the source distribution is simplistic and uninteresting, but | |
195 | may still be what you want. | |
196 | .Sh "How do I debug my Perl programs?" | |
197 | .IX Subsection "How do I debug my Perl programs?" | |
198 | Have you tried \f(CW\*(C`use warnings\*(C'\fR or used \f(CW\*(C`\-w\*(C'\fR? They enable warnings | |
199 | to detect dubious practices. | |
200 | .PP | |
201 | Have you tried \f(CW\*(C`use strict\*(C'\fR? It prevents you from using symbolic | |
202 | references, makes you predeclare any subroutines that you call as bare | |
203 | words, and (probably most importantly) forces you to predeclare your | |
204 | variables with \f(CW\*(C`my\*(C'\fR, \f(CW\*(C`our\*(C'\fR, or \f(CW\*(C`use vars\*(C'\fR. | |
205 | .PP | |
206 | Did you check the return values of each and every system call? The operating | |
207 | system (and thus Perl) tells you whether they worked, and if not | |
208 | why. | |
209 | .PP | |
210 | .Vb 2 | |
211 | \& open(FH, "> /etc/cantwrite") | |
212 | \& or die "Couldn't write to /etc/cantwrite: $!\en"; | |
213 | .Ve | |
214 | .PP | |
215 | Did you read perltrap? It's full of gotchas for old and new Perl | |
216 | programmers and even has sections for those of you who are upgrading | |
217 | from languages like \fIawk\fR and \fIC\fR. | |
218 | .PP | |
219 | Have you tried the Perl debugger, described in perldebug? You can | |
220 | step through your program and see what it's doing and thus work out | |
221 | why what it's doing isn't what it should be doing. | |
222 | .Sh "How do I profile my Perl programs?" | |
223 | .IX Subsection "How do I profile my Perl programs?" | |
224 | You should get the Devel::DProf module from the standard distribution | |
225 | (or separately on \s-1CPAN\s0) and also use Benchmark.pm from the standard | |
226 | distribution. The Benchmark module lets you time specific portions of | |
227 | your code, while Devel::DProf gives detailed breakdowns of where your | |
228 | code spends its time. | |
229 | .PP | |
230 | Here's a sample use of Benchmark: | |
231 | .PP | |
232 | .Vb 1 | |
233 | \& use Benchmark; | |
234 | .Ve | |
235 | .PP | |
236 | .Vb 2 | |
237 | \& @junk = `cat /etc/motd`; | |
238 | \& $count = 10_000; | |
239 | .Ve | |
240 | .PP | |
241 | .Vb 10 | |
242 | \& timethese($count, { | |
243 | \& 'map' => sub { my @a = @junk; | |
244 | \& map { s/a/b/ } @a; | |
245 | \& return @a | |
246 | \& }, | |
247 | \& 'for' => sub { my @a = @junk; | |
248 | \& local $_; | |
249 | \& for (@a) { s/a/b/ }; | |
250 | \& return @a }, | |
251 | \& }); | |
252 | .Ve | |
253 | .PP | |
254 | This is what it prints (on one machine\*(--your results will be dependent | |
255 | on your hardware, operating system, and the load on your machine): | |
256 | .PP | |
257 | .Vb 3 | |
258 | \& Benchmark: timing 10000 iterations of for, map... | |
259 | \& for: 4 secs ( 3.97 usr 0.01 sys = 3.98 cpu) | |
260 | \& map: 6 secs ( 4.97 usr 0.00 sys = 4.97 cpu) | |
261 | .Ve | |
262 | .PP | |
263 | Be aware that a good benchmark is very hard to write. It only tests the | |
264 | data you give it and proves little about the differing complexities | |
265 | of contrasting algorithms. | |
266 | .Sh "How do I cross-reference my Perl programs?" | |
267 | .IX Subsection "How do I cross-reference my Perl programs?" | |
268 | The B::Xref module can be used to generate cross-reference reports | |
269 | for Perl programs. | |
270 | .PP | |
271 | .Vb 1 | |
272 | \& perl -MO=Xref[,OPTIONS] scriptname.plx | |
273 | .Ve | |
274 | .Sh "Is there a pretty-printer (formatter) for Perl?" | |
275 | .IX Subsection "Is there a pretty-printer (formatter) for Perl?" | |
276 | Perltidy is a Perl script which indents and reformats Perl scripts | |
277 | to make them easier to read by trying to follow the rules of the | |
278 | perlstyle. If you write Perl scripts, or spend much time reading | |
279 | them, you will probably find it useful. It is available at | |
280 | http://perltidy.sourceforge.net | |
281 | .PP | |
282 | Of course, if you simply follow the guidelines in perlstyle, | |
283 | you shouldn't need to reformat. The habit of formatting your code | |
284 | as you write it will help prevent bugs. Your editor can and should | |
285 | help you with this. The perl-mode or newer cperl-mode for emacs | |
286 | can provide remarkable amounts of help with most (but not all) | |
287 | code, and even less programmable editors can provide significant | |
288 | assistance. Tom Christiansen and many other \s-1VI\s0 users swear by | |
289 | the following settings in vi and its clones: | |
290 | .PP | |
291 | .Vb 2 | |
292 | \& set ai sw=4 | |
293 | \& map! ^O {^M}^[O^T | |
294 | .Ve | |
295 | .PP | |
296 | Put that in your \fI.exrc\fR file (replacing the caret characters | |
297 | with control characters) and away you go. In insert mode, ^T is | |
298 | for indenting, ^D is for undenting, and ^O is for blockdenting\*(-- | |
299 | as it were. A more complete example, with comments, can be found at | |
300 | http://www.cpan.org/authors/id/TOMC/scripts/toms.exrc.gz | |
301 | .PP | |
302 | The a2ps http://www\-inf.enst.fr/%7Edemaille/a2ps/black+white.ps does | |
303 | lots of things related to generating nicely printed output of | |
304 | documents, as does enscript at http://people.ssh.fi/mtr/genscript/ . | |
305 | .Sh "Is there a ctags for Perl?" | |
306 | .IX Subsection "Is there a ctags for Perl?" | |
307 | Recent versions of ctags do much more than older versions did. | |
308 | \&\s-1EXUBERANT\s0 \s-1CTAGS\s0 is available from http://ctags.sourceforge.net/ | |
309 | and does a good job of making tags files for perl code. | |
310 | .PP | |
311 | There is also a simple one at | |
312 | http://www.cpan.org/authors/id/TOMC/scripts/ptags.gz which may do | |
313 | the trick. It can be easy to hack this into what you want. | |
314 | .Sh "Is there an \s-1IDE\s0 or Windows Perl Editor?" | |
315 | .IX Subsection "Is there an IDE or Windows Perl Editor?" | |
316 | Perl programs are just plain text, so any editor will do. | |
317 | .PP | |
318 | If you're on Unix, you already have an IDE\*(--Unix itself. The \s-1UNIX\s0 | |
319 | philosophy is the philosophy of several small tools that each do one | |
320 | thing and do it well. It's like a carpenter's toolbox. | |
321 | .PP | |
322 | If you want an \s-1IDE\s0, check the following: | |
323 | .IP "Komodo" 4 | |
324 | .IX Item "Komodo" | |
325 | ActiveState's cross-platform (as of April 2001 Windows and Linux), | |
326 | multi-language \s-1IDE\s0 has Perl support, including a regular expression | |
327 | debugger and remote debugging | |
328 | ( http://www.ActiveState.com/Products/Komodo/index.html ). (Visual | |
329 | Perl, a Visual Studio.NET plug-in is currently (early 2001) in beta | |
330 | ( http://www.ActiveState.com/Products/VisualPerl/index.html )). | |
331 | .IP "The Object System" 4 | |
332 | .IX Item "The Object System" | |
333 | ( http://www.castlelink.co.uk/object_system/ ) is a Perl web | |
334 | applications development \s-1IDE\s0, apparently for any platform | |
335 | that runs Perl. | |
336 | .IP "Open Perl \s-1IDE\s0" 4 | |
337 | .IX Item "Open Perl IDE" | |
338 | ( http://open\-perl\-ide.sourceforge.net/ ) | |
339 | Open Perl \s-1IDE\s0 is an integrated development environment for writing | |
340 | and debugging Perl scripts with ActiveState's ActivePerl distribution | |
341 | under Windows 95/98/NT/2000. | |
342 | .IP "PerlBuilder" 4 | |
343 | .IX Item "PerlBuilder" | |
344 | ( http://www.solutionsoft.com/perl.htm ) is an integrated development | |
345 | environment for Windows that supports Perl development. | |
346 | .IP "visiPerl+" 4 | |
347 | .IX Item "visiPerl+" | |
348 | ( http://helpconsulting.net/visiperl/ ) | |
349 | From Help Consulting, for Windows. | |
350 | .IP "OptiPerl" 4 | |
351 | .IX Item "OptiPerl" | |
352 | ( http://www.optiperl.com/ ) is a Windows \s-1IDE\s0 with simulated \s-1CGI\s0 | |
353 | environment, including debugger and syntax highlighting editor. | |
354 | .PP | |
355 | For Windows there's also the | |
356 | .IP "CodeMagicCD" 4 | |
357 | .IX Item "CodeMagicCD" | |
358 | ( http://www.codemagiccd.com/ ) Collection of various programming | |
359 | tools for Windows: Perl (5.005_03), TclTk, Python, \s-1GNU\s0 programming | |
360 | tools, \s-1REBOL\s0, wxWindows toolkit, the MinGW \s-1GNU\s0 C/\*(C+ compiler, \s-1DJGPP\s0 | |
361 | \&\s-1GNU\s0 C/\*(C+ compiler, Cint C interpreter, YaBasic. | |
362 | .PP | |
363 | For editors: if you're on Unix you probably have vi or a vi clone already, | |
364 | and possibly an emacs too, so you may not need to download anything. | |
365 | In any emacs the cperl-mode (M\-x cperl\-mode) gives you perhaps the | |
366 | best available Perl editing mode in any editor. | |
367 | .PP | |
368 | If you are using Windows, you can use any editor that lets | |
369 | you work with plain text, such as NotePad or WordPad. Word | |
370 | processors, such as Microsoft Word or WordPerfect, typically | |
371 | do not work since they insert all sorts of behind-the-scenes | |
372 | information, although some allow you to save files as \*(L"Text | |
373 | Only\*(R". You can also download text editors designed | |
374 | specifically for programming, such as Textpad | |
375 | ( http://www.textpad.com/ ) and UltraEdit | |
376 | ( http://www.ultraedit.com/ ), among others. | |
377 | .PP | |
378 | If you are using Mac \s-1OS\s0, the same concerns apply. MacPerl | |
379 | (for Classic environments) comes with a simple editor. | |
380 | Popular external editors are BBEdit ( http://www.bbedit.com/ ) | |
381 | or Alpha ( http://www.kelehers.org/alpha/ ). Mac \s-1OS\s0 X users can | |
382 | use Unix editors as well. | |
383 | .IP "\s-1GNU\s0 Emacs" 4 | |
384 | .IX Item "GNU Emacs" | |
385 | http://www.gnu.org/software/emacs/windows/ntemacs.html | |
386 | .IP "MicroEMACS" 4 | |
387 | .IX Item "MicroEMACS" | |
388 | http://members.nbci.com/uemacs/ | |
389 | .IP "XEmacs" 4 | |
390 | .IX Item "XEmacs" | |
391 | http://www.xemacs.org/Download/index.html | |
392 | .PP | |
393 | or a vi clone such as | |
394 | .IP "Elvis" 4 | |
395 | .IX Item "Elvis" | |
396 | ftp://ftp.cs.pdx.edu/pub/elvis/ http://www.fh\-wedel.de/elvis/ | |
397 | .IP "Vile" 4 | |
398 | .IX Item "Vile" | |
399 | http://vile.cx/ | |
400 | .IP "Vim" 4 | |
401 | .IX Item "Vim" | |
402 | http://www.vim.org/ | |
403 | .Sp | |
404 | win32: http://www.cs.vu.nl/%7Etmgil/vi.html | |
405 | .PP | |
406 | For vi lovers in general, Windows or elsewhere: | |
407 | .PP | |
408 | .Vb 1 | |
409 | \& http://www.thomer.com/thomer/vi/vi.html | |
410 | .Ve | |
411 | .PP | |
412 | nvi ( http://www.bostic.com/vi/ , available from \s-1CPAN\s0 in src/misc/) is | |
413 | yet another vi clone, unfortunately not available for Windows, but in | |
414 | \&\s-1UNIX\s0 platforms you might be interested in trying it out, firstly because | |
415 | strictly speaking it is not a vi clone, it is the real vi, or the new | |
416 | incarnation of it, and secondly because you can embed Perl inside it | |
417 | to use Perl as the scripting language. nvi is not alone in this, | |
418 | though: at least also vim and vile offer an embedded Perl. | |
419 | .PP | |
420 | The following are Win32 multilanguage editor/IDESs that support Perl: | |
421 | .IP "Codewright" 4 | |
422 | .IX Item "Codewright" | |
423 | http://www.starbase.com/ | |
424 | .IP "MultiEdit" 4 | |
425 | .IX Item "MultiEdit" | |
426 | http://www.MultiEdit.com/ | |
427 | .IP "SlickEdit" 4 | |
428 | .IX Item "SlickEdit" | |
429 | http://www.slickedit.com/ | |
430 | .PP | |
431 | There is also a toyedit Text widget based editor written in Perl | |
432 | that is distributed with the Tk module on \s-1CPAN\s0. The ptkdb | |
433 | ( http://world.std.com/~aep/ptkdb/ ) is a Perl/tk based debugger that | |
434 | acts as a development environment of sorts. Perl Composer | |
435 | ( http://perlcomposer.sourceforge.net/vperl.html ) is an \s-1IDE\s0 for Perl/Tk | |
436 | \&\s-1GUI\s0 creation. | |
437 | .PP | |
438 | In addition to an editor/IDE you might be interested in a more | |
439 | powerful shell environment for Win32. Your options include | |
440 | .IP "Bash" 4 | |
441 | .IX Item "Bash" | |
442 | from the Cygwin package ( http://sources.redhat.com/cygwin/ ) | |
443 | .IP "Ksh" 4 | |
444 | .IX Item "Ksh" | |
445 | from the \s-1MKS\s0 Toolkit ( http://www.mks.com/ ), or the Bourne shell of | |
446 | the U/WIN environment ( http://www.research.att.com/sw/tools/uwin/ ) | |
447 | .IP "Tcsh" 4 | |
448 | .IX Item "Tcsh" | |
449 | ftp://ftp.astron.com/pub/tcsh/ , see also | |
450 | http://www.primate.wisc.edu/software/csh\-tcsh\-book/ | |
451 | .IP "Zsh" 4 | |
452 | .IX Item "Zsh" | |
453 | ftp://ftp.blarg.net/users/amol/zsh/ , see also http://www.zsh.org/ | |
454 | .PP | |
455 | \&\s-1MKS\s0 and U/WIN are commercial (U/WIN is free for educational and | |
456 | research purposes), Cygwin is covered by the \s-1GNU\s0 Public License (but | |
457 | that shouldn't matter for Perl use). The Cygwin, \s-1MKS\s0, and U/WIN all | |
458 | contain (in addition to the shells) a comprehensive set of standard | |
459 | \&\s-1UNIX\s0 toolkit utilities. | |
460 | .PP | |
461 | If you're transferring text files between Unix and Windows using \s-1FTP\s0 | |
462 | be sure to transfer them in \s-1ASCII\s0 mode so the ends of lines are | |
463 | appropriately converted. | |
464 | .PP | |
465 | On Mac \s-1OS\s0 the MacPerl Application comes with a simple 32k text editor | |
466 | that behaves like a rudimentary \s-1IDE\s0. In contrast to the MacPerl Application | |
467 | the \s-1MPW\s0 Perl tool can make use of the \s-1MPW\s0 Shell itself as an editor (with | |
468 | no 32k limit). | |
469 | .IP "BBEdit and BBEdit Lite" 4 | |
470 | .IX Item "BBEdit and BBEdit Lite" | |
471 | are text editors for Mac \s-1OS\s0 that have a Perl sensitivity mode | |
472 | ( http://web.barebones.com/ ). | |
473 | .IP "Alpha" 4 | |
474 | .IX Item "Alpha" | |
475 | is an editor, written and extensible in Tcl, that nonetheless has | |
476 | built in support for several popular markup and programming languages | |
477 | including Perl and \s-1HTML\s0 ( http://alpha.olm.net/ ). | |
478 | .PP | |
479 | Pepper and Pe are programming language sensitive text editors for Mac | |
480 | \&\s-1OS\s0 X and BeOS respectively ( http://www.hekkelman.com/ ). | |
481 | .Sh "Where can I get Perl macros for vi?" | |
482 | .IX Subsection "Where can I get Perl macros for vi?" | |
483 | For a complete version of Tom Christiansen's vi configuration file, | |
484 | see http://www.cpan.org/authors/Tom_Christiansen/scripts/toms.exrc.gz , | |
485 | the standard benchmark file for vi emulators. The file runs best with nvi, | |
486 | the current version of vi out of Berkeley, which incidentally can be built | |
487 | with an embedded Perl interpreter\*(--see http://www.cpan.org/src/misc/ . | |
488 | .Sh "Where can I get perl-mode for emacs?" | |
489 | .IX Subsection "Where can I get perl-mode for emacs?" | |
490 | Since Emacs version 19 patchlevel 22 or so, there have been both a | |
491 | perl\-mode.el and support for the Perl debugger built in. These should | |
492 | come with the standard Emacs 19 distribution. | |
493 | .PP | |
494 | In the Perl source directory, you'll find a directory called \*(L"emacs\*(R", | |
495 | which contains a cperl-mode that color-codes keywords, provides | |
496 | context-sensitive help, and other nifty things. | |
497 | .PP | |
498 | Note that the perl-mode of emacs will have fits with \f(CW"main'foo"\fR | |
499 | (single quote), and mess up the indentation and highlighting. You | |
500 | are probably using \f(CW"main::foo"\fR in new Perl code anyway, so this | |
501 | shouldn't be an issue. | |
502 | .Sh "How can I use curses with Perl?" | |
503 | .IX Subsection "How can I use curses with Perl?" | |
504 | The Curses module from \s-1CPAN\s0 provides a dynamically loadable object | |
505 | module interface to a curses library. A small demo can be found at the | |
506 | directory http://www.cpan.org/authors/Tom_Christiansen/scripts/rep ; | |
507 | this program repeats a command and updates the screen as needed, rendering | |
508 | \&\fBrep ps axu\fR similar to \fBtop\fR. | |
509 | .Sh "How can I use X or Tk with Perl?" | |
510 | .IX Subsection "How can I use X or Tk with Perl?" | |
511 | Tk is a completely Perl\-based, object-oriented interface to the Tk toolkit | |
512 | that doesn't force you to use Tcl just to get at Tk. Sx is an interface | |
513 | to the Athena Widget set. Both are available from \s-1CPAN\s0. See the | |
514 | directory http://www.cpan.org/modules/by\-category/08_User_Interfaces/ | |
515 | .PP | |
516 | Invaluable for Perl/Tk programming are the Perl/Tk \s-1FAQ\s0 at | |
517 | http://w4.lns.cornell.edu/%7Epvhp/ptk/ptkTOC.html , the Perl/Tk Reference | |
518 | Guide available at | |
519 | http://www.cpan.org/authors/Stephen_O_Lidie/ , and the | |
520 | online manpages at | |
521 | http://www\-users.cs.umn.edu/%7Eamundson/perl/perltk/toc.html . | |
522 | .Sh "How can I generate simple menus without using \s-1CGI\s0 or Tk?" | |
523 | .IX Subsection "How can I generate simple menus without using CGI or Tk?" | |
524 | The http://www.cpan.org/authors/id/SKUNZ/perlmenu.v4.0.tar.gz | |
525 | module, which is curses\-based, can help with this. | |
526 | .Sh "How can I make my Perl program run faster?" | |
527 | .IX Subsection "How can I make my Perl program run faster?" | |
528 | The best way to do this is to come up with a better algorithm. This | |
529 | can often make a dramatic difference. Jon Bentley's book | |
530 | ``Programming Pearls'' (that's not a misspelling!) has some good tips | |
531 | on optimization, too. Advice on benchmarking boils down to: benchmark | |
532 | and profile to make sure you're optimizing the right part, look for | |
533 | better algorithms instead of microtuning your code, and when all else | |
534 | fails consider just buying faster hardware. You will probably want to | |
535 | read the answer to the earlier question ``How do I profile my Perl programs?'' | |
536 | if you haven't done so already. | |
537 | .PP | |
538 | A different approach is to autoload seldom-used Perl code. See the | |
539 | AutoSplit and AutoLoader modules in the standard distribution for | |
540 | that. Or you could locate the bottleneck and think about writing just | |
541 | that part in C, the way we used to take bottlenecks in C code and | |
542 | write them in assembler. Similar to rewriting in C, | |
543 | modules that have critical sections can be written in C (for instance, the | |
544 | \&\s-1PDL\s0 module from \s-1CPAN\s0). | |
545 | .PP | |
546 | In some cases, it may be worth it to use the backend compiler to | |
547 | produce byte code (saving compilation time) or compile into C, which | |
548 | will certainly save compilation time and sometimes a small amount (but | |
549 | not much) execution time. See the question about compiling your Perl | |
550 | programs for more on the compiler\*(--the wins aren't as obvious as you'd | |
551 | hope. | |
552 | .PP | |
553 | If you're currently linking your perl executable to a shared \fIlibc.so\fR, | |
554 | you can often gain a 10\-25% performance benefit by rebuilding it to | |
555 | link with a static libc.a instead. This will make a bigger perl | |
556 | executable, but your Perl programs (and programmers) may thank you for | |
557 | it. See the \fI\s-1INSTALL\s0\fR file in the source distribution for more | |
558 | information. | |
559 | .PP | |
560 | Unsubstantiated reports allege that Perl interpreters that use sfio | |
561 | outperform those that don't (for I/O intensive applications). To try | |
562 | this, see the \fI\s-1INSTALL\s0\fR file in the source distribution, especially | |
563 | the ``Selecting File I/O mechanisms'' section. | |
564 | .PP | |
565 | The undump program was an old attempt to speed up your Perl program | |
566 | by storing the already-compiled form to disk. This is no longer | |
567 | a viable option, as it only worked on a few architectures, and | |
568 | wasn't a good solution anyway. | |
569 | .Sh "How can I make my Perl program take less memory?" | |
570 | .IX Subsection "How can I make my Perl program take less memory?" | |
571 | When it comes to time-space tradeoffs, Perl nearly always prefers to | |
572 | throw memory at a problem. Scalars in Perl use more memory than | |
573 | strings in C, arrays take more than that, and hashes use even more. While | |
574 | there's still a lot to be done, recent releases have been addressing | |
575 | these issues. For example, as of 5.004, duplicate hash keys are | |
576 | shared amongst all hashes using them, so require no reallocation. | |
577 | .PP | |
578 | In some cases, using \fIsubstr()\fR or \fIvec()\fR to simulate arrays can be | |
579 | highly beneficial. For example, an array of a thousand booleans will | |
580 | take at least 20,000 bytes of space, but it can be turned into one | |
581 | 125\-byte bit vector\*(--a considerable memory savings. The standard | |
582 | Tie::SubstrHash module can also help for certain types of data | |
583 | structure. If you're working with specialist data structures | |
584 | (matrices, for instance) modules that implement these in C may use | |
585 | less memory than equivalent Perl modules. | |
586 | .PP | |
587 | Another thing to try is learning whether your Perl was compiled with | |
588 | the system malloc or with Perl's builtin malloc. Whichever one it | |
589 | is, try using the other one and see whether this makes a difference. | |
590 | Information about malloc is in the \fI\s-1INSTALL\s0\fR file in the source | |
591 | distribution. You can find out whether you are using perl's malloc by | |
592 | typing \f(CW\*(C`perl \-V:usemymalloc\*(C'\fR. | |
593 | .PP | |
594 | Of course, the best way to save memory is to not do anything to waste | |
595 | it in the first place. Good programming practices can go a long way | |
596 | toward this: | |
597 | .IP "\(bu Don't slurp!" 4 | |
598 | .IX Item "Don't slurp!" | |
599 | Don't read an entire file into memory if you can process it line | |
600 | by line. Or more concretely, use a loop like this: | |
601 | .Sp | |
602 | .Vb 6 | |
603 | \& # | |
604 | \& # Good Idea | |
605 | \& # | |
606 | \& while (<FILE>) { | |
607 | \& # ... | |
608 | \& } | |
609 | .Ve | |
610 | .Sp | |
611 | instead of this: | |
612 | .Sp | |
613 | .Vb 7 | |
614 | \& # | |
615 | \& # Bad Idea | |
616 | \& # | |
617 | \& @data = <FILE>; | |
618 | \& foreach (@data) { | |
619 | \& # ... | |
620 | \& } | |
621 | .Ve | |
622 | .Sp | |
623 | When the files you're processing are small, it doesn't much matter which | |
624 | way you do it, but it makes a huge difference when they start getting | |
625 | larger. | |
626 | .IP "\(bu Use map and grep selectively" 4 | |
627 | .IX Item "Use map and grep selectively" | |
628 | Remember that both map and grep expect a \s-1LIST\s0 argument, so doing this: | |
629 | .Sp | |
630 | .Vb 1 | |
631 | \& @wanted = grep {/pattern/} <FILE>; | |
632 | .Ve | |
633 | .Sp | |
634 | will cause the entire file to be slurped. For large files, it's better | |
635 | to loop: | |
636 | .Sp | |
637 | .Vb 3 | |
638 | \& while (<FILE>) { | |
639 | \& push(@wanted, $_) if /pattern/; | |
640 | \& } | |
641 | .Ve | |
642 | .IP "\(bu Avoid unnecessary quotes and stringification" 4 | |
643 | .IX Item "Avoid unnecessary quotes and stringification" | |
644 | Don't quote large strings unless absolutely necessary: | |
645 | .Sp | |
646 | .Vb 1 | |
647 | \& my $copy = "$large_string"; | |
648 | .Ve | |
649 | .Sp | |
650 | makes 2 copies of \f(CW$large_string\fR (one for \f(CW$copy\fR and another for the | |
651 | quotes), whereas | |
652 | .Sp | |
653 | .Vb 1 | |
654 | \& my $copy = $large_string; | |
655 | .Ve | |
656 | .Sp | |
657 | only makes one copy. | |
658 | .Sp | |
659 | Ditto for stringifying large arrays: | |
660 | .Sp | |
661 | .Vb 4 | |
662 | \& { | |
663 | \& local $, = "\en"; | |
664 | \& print @big_array; | |
665 | \& } | |
666 | .Ve | |
667 | .Sp | |
668 | is much more memory-efficient than either | |
669 | .Sp | |
670 | .Vb 1 | |
671 | \& print join "\en", @big_array; | |
672 | .Ve | |
673 | .Sp | |
674 | or | |
675 | .Sp | |
676 | .Vb 4 | |
677 | \& { | |
678 | \& local $" = "\en"; | |
679 | \& print "@big_array"; | |
680 | \& } | |
681 | .Ve | |
682 | .IP "\(bu Pass by reference" 4 | |
683 | .IX Item "Pass by reference" | |
684 | Pass arrays and hashes by reference, not by value. For one thing, it's | |
685 | the only way to pass multiple lists or hashes (or both) in a single | |
686 | call/return. It also avoids creating a copy of all the contents. This | |
687 | requires some judgment, however, because any changes will be propagated | |
688 | back to the original data. If you really want to mangle (er, modify) a | |
689 | copy, you'll have to sacrifice the memory needed to make one. | |
690 | .IP "\(bu Tie large variables to disk." 4 | |
691 | .IX Item "Tie large variables to disk." | |
692 | For \*(L"big\*(R" data stores (i.e. ones that exceed available memory) consider | |
693 | using one of the \s-1DB\s0 modules to store it on disk instead of in \s-1RAM\s0. This | |
694 | will incur a penalty in access time, but that's probably better than | |
695 | causing your hard disk to thrash due to massive swapping. | |
696 | .Sh "Is it unsafe to return a pointer to local data?" | |
697 | .IX Subsection "Is it unsafe to return a pointer to local data?" | |
698 | No, Perl's garbage collection system takes care of this. | |
699 | .PP | |
700 | .Vb 4 | |
701 | \& sub makeone { | |
702 | \& my @a = ( 1 .. 10 ); | |
703 | \& return \e@a; | |
704 | \& } | |
705 | .Ve | |
706 | .PP | |
707 | .Vb 3 | |
708 | \& for $i ( 1 .. 10 ) { | |
709 | \& push @many, makeone(); | |
710 | \& } | |
711 | .Ve | |
712 | .PP | |
713 | .Vb 1 | |
714 | \& print $many[4][5], "\en"; | |
715 | .Ve | |
716 | .PP | |
717 | .Vb 1 | |
718 | \& print "@many\en"; | |
719 | .Ve | |
720 | .Sh "How can I free an array or hash so my program shrinks?" | |
721 | .IX Subsection "How can I free an array or hash so my program shrinks?" | |
722 | You usually can't. On most operating systems, memory | |
723 | allocated to a program can never be returned to the system. | |
724 | That's why long-running programs sometimes re-exec | |
725 | themselves. Some operating systems (notably, systems that | |
726 | use \fImmap\fR\|(2) for allocating large chunks of memory) can | |
727 | reclaim memory that is no longer used, but on such systems, | |
728 | perl must be configured and compiled to use the \s-1OS\s0's malloc, | |
729 | not perl's. | |
730 | .PP | |
731 | However, judicious use of \fImy()\fR on your variables will help make sure | |
732 | that they go out of scope so that Perl can free up that space for | |
733 | use in other parts of your program. A global variable, of course, never | |
734 | goes out of scope, so you can't get its space automatically reclaimed, | |
735 | although \fIundef()\fRing and/or \fIdelete()\fRing it will achieve the same effect. | |
736 | In general, memory allocation and de-allocation isn't something you can | |
737 | or should be worrying about much in Perl, but even this capability | |
738 | (preallocation of data types) is in the works. | |
739 | .Sh "How can I make my \s-1CGI\s0 script more efficient?" | |
740 | .IX Subsection "How can I make my CGI script more efficient?" | |
741 | Beyond the normal measures described to make general Perl programs | |
742 | faster or smaller, a \s-1CGI\s0 program has additional issues. It may be run | |
743 | several times per second. Given that each time it runs it will need | |
744 | to be re-compiled and will often allocate a megabyte or more of system | |
745 | memory, this can be a killer. Compiling into C \fBisn't going to help | |
746 | you\fR because the process start-up overhead is where the bottleneck is. | |
747 | .PP | |
748 | There are two popular ways to avoid this overhead. One solution | |
749 | involves running the Apache \s-1HTTP\s0 server (available from | |
750 | http://www.apache.org/ ) with either of the mod_perl or mod_fastcgi | |
751 | plugin modules. | |
752 | .PP | |
753 | With mod_perl and the Apache::Registry module (distributed with | |
754 | mod_perl), httpd will run with an embedded Perl interpreter which | |
755 | pre-compiles your script and then executes it within the same address | |
756 | space without forking. The Apache extension also gives Perl access to | |
757 | the internal server \s-1API\s0, so modules written in Perl can do just about | |
758 | anything a module written in C can. For more on mod_perl, see | |
759 | http://perl.apache.org/ | |
760 | .PP | |
761 | With the \s-1FCGI\s0 module (from \s-1CPAN\s0) and the mod_fastcgi | |
762 | module (available from http://www.fastcgi.com/ ) each of your Perl | |
763 | programs becomes a permanent \s-1CGI\s0 daemon process. | |
764 | .PP | |
765 | Both of these solutions can have far-reaching effects on your system | |
766 | and on the way you write your \s-1CGI\s0 programs, so investigate them with | |
767 | care. | |
768 | .PP | |
769 | See http://www.cpan.org/modules/by\-category/15_World_Wide_Web_HTML_HTTP_CGI/ . | |
770 | .PP | |
771 | A non\-free, commercial product, ``The Velocity Engine for Perl'', | |
772 | (http://www.binevolve.com/ or http://www.binevolve.com/velocigen/ ) | |
773 | might also be worth looking at. It will allow you to increase the | |
774 | performance of your Perl programs, running programs up to 25 times | |
775 | faster than normal \s-1CGI\s0 Perl when running in persistent Perl mode or 4 | |
776 | to 5 times faster without any modification to your existing \s-1CGI\s0 | |
777 | programs. Fully functional evaluation copies are available from the | |
778 | web site. | |
779 | .Sh "How can I hide the source for my Perl program?" | |
780 | .IX Subsection "How can I hide the source for my Perl program?" | |
781 | Delete it. :\-) Seriously, there are a number of (mostly | |
782 | unsatisfactory) solutions with varying levels of ``security''. | |
783 | .PP | |
784 | First of all, however, you \fIcan't\fR take away read permission, because | |
785 | the source code has to be readable in order to be compiled and | |
786 | interpreted. (That doesn't mean that a \s-1CGI\s0 script's source is | |
787 | readable by people on the web, though\*(--only by people with access to | |
788 | the filesystem.) So you have to leave the permissions at the socially | |
789 | friendly 0755 level. | |
790 | .PP | |
791 | Some people regard this as a security problem. If your program does | |
792 | insecure things and relies on people not knowing how to exploit those | |
793 | insecurities, it is not secure. It is often possible for someone to | |
794 | determine the insecure things and exploit them without viewing the | |
795 | source. Security through obscurity, the name for hiding your bugs | |
796 | instead of fixing them, is little security indeed. | |
797 | .PP | |
798 | You can try using encryption via source filters (Starting from Perl | |
799 | 5.8 the Filter::Simple and Filter::Util::Call modules are included in | |
800 | the standard distribution), but any decent programmer will be able to | |
801 | decrypt it. You can try using the byte code compiler and interpreter | |
802 | described below, but the curious might still be able to de-compile it. | |
803 | You can try using the native-code compiler described below, but | |
804 | crackers might be able to disassemble it. These pose varying degrees | |
805 | of difficulty to people wanting to get at your code, but none can | |
806 | definitively conceal it (true of every language, not just Perl). | |
807 | .PP | |
808 | If you're concerned about people profiting from your code, then the | |
809 | bottom line is that nothing but a restrictive license will give you | |
810 | legal security. License your software and pepper it with threatening | |
811 | statements like ``This is unpublished proprietary software of \s-1XYZ\s0 Corp. | |
812 | Your access to it does not give you permission to use it blah blah | |
813 | blah.'' We are not lawyers, of course, so you should see a lawyer if | |
814 | you want to be sure your license's wording will stand up in court. | |
815 | .Sh "How can I compile my Perl program into byte code or C?" | |
816 | .IX Subsection "How can I compile my Perl program into byte code or C?" | |
817 | Malcolm Beattie has written a multifunction backend compiler, | |
818 | available from \s-1CPAN\s0, that can do both these things. It is included | |
819 | in the perl5.005 release, but is still considered experimental. | |
820 | This means it's fun to play with if you're a programmer but not | |
821 | really for people looking for turn-key solutions. | |
822 | .PP | |
823 | Merely compiling into C does not in and of itself guarantee that your | |
824 | code will run very much faster. That's because except for lucky cases | |
825 | where a lot of native type inferencing is possible, the normal Perl | |
826 | run-time system is still present and so your program will take just as | |
827 | long to run and be just as big. Most programs save little more than | |
828 | compilation time, leaving execution no more than 10\-30% faster. A few | |
829 | rare programs actually benefit significantly (even running several times | |
830 | faster), but this takes some tweaking of your code. | |
831 | .PP | |
832 | You'll probably be astonished to learn that the current version of the | |
833 | compiler generates a compiled form of your script whose executable is | |
834 | just as big as the original perl executable, and then some. That's | |
835 | because as currently written, all programs are prepared for a full | |
836 | \&\fIeval()\fR statement. You can tremendously reduce this cost by building a | |
837 | shared \fIlibperl.so\fR library and linking against that. See the | |
838 | \&\fI\s-1INSTALL\s0\fR podfile in the Perl source distribution for details. If | |
839 | you link your main perl binary with this, it will make it minuscule. | |
840 | For example, on one author's system, \fI/usr/bin/perl\fR is only 11k in | |
841 | size! | |
842 | .PP | |
843 | In general, the compiler will do nothing to make a Perl program smaller, | |
844 | faster, more portable, or more secure. In fact, it can make your | |
845 | situation worse. The executable will be bigger, your \s-1VM\s0 system may take | |
846 | longer to load the whole thing, the binary is fragile and hard to fix, | |
847 | and compilation never stopped software piracy in the form of crackers, | |
848 | viruses, or bootleggers. The real advantage of the compiler is merely | |
849 | packaging, and once you see the size of what it makes (well, unless | |
850 | you use a shared \fIlibperl.so\fR), you'll probably want a complete | |
851 | Perl install anyway. | |
852 | .Sh "How can I compile Perl into Java?" | |
853 | .IX Subsection "How can I compile Perl into Java?" | |
854 | You can also integrate Java and Perl with the | |
855 | Perl Resource Kit from O'Reilly and Associates. See | |
856 | http://www.oreilly.com/catalog/prkunix/ . | |
857 | .PP | |
858 | Perl 5.6 comes with Java Perl Lingo, or \s-1JPL\s0. \s-1JPL\s0, still in | |
859 | development, allows Perl code to be called from Java. See jpl/README | |
860 | in the Perl source tree. | |
861 | .ie n .Sh "How can I get ""#!perl"" to work on [\s-1MS\-DOS\s0,NT,...]?" | |
862 | .el .Sh "How can I get \f(CW#!perl\fP to work on [\s-1MS\-DOS\s0,NT,...]?" | |
863 | .IX Subsection "How can I get #!perl to work on [MS-DOS,NT,...]?" | |
864 | For \s-1OS/2\s0 just use | |
865 | .PP | |
866 | .Vb 1 | |
867 | \& extproc perl -S -your_switches | |
868 | .Ve | |
869 | .PP | |
870 | as the first line in \f(CW\*(C`*.cmd\*(C'\fR file (\f(CW\*(C`\-S\*(C'\fR due to a bug in cmd.exe's | |
871 | `extproc' handling). For \s-1DOS\s0 one should first invent a corresponding | |
872 | batch file and codify it in \f(CW\*(C`ALTERNATIVE_SHEBANG\*(C'\fR (see the | |
873 | \&\fI\s-1INSTALL\s0\fR file in the source distribution for more information). | |
874 | .PP | |
875 | The Win95/NT installation, when using the ActiveState port of Perl, | |
876 | will modify the Registry to associate the \f(CW\*(C`.pl\*(C'\fR extension with the | |
877 | perl interpreter. If you install another port, perhaps even building | |
878 | your own Win95/NT Perl from the standard sources by using a Windows port | |
879 | of gcc (e.g., with cygwin or mingw32), then you'll have to modify | |
880 | the Registry yourself. In addition to associating \f(CW\*(C`.pl\*(C'\fR with the | |
881 | interpreter, \s-1NT\s0 people can use: \f(CW\*(C`SET PATHEXT=%PATHEXT%;.PL\*(C'\fR to let them | |
882 | run the program \f(CW\*(C`install\-linux.pl\*(C'\fR merely by typing \f(CW\*(C`install\-linux\*(C'\fR. | |
883 | .PP | |
884 | Macintosh Perl programs will have the appropriate Creator and | |
885 | Type, so that double-clicking them will invoke the Perl application. | |
886 | .PP | |
887 | \&\fI\s-1IMPORTANT\s0!\fR: Whatever you do, \s-1PLEASE\s0 don't get frustrated, and just | |
888 | throw the perl interpreter into your cgi-bin directory, in order to | |
889 | get your programs working for a web server. This is an \s-1EXTREMELY\s0 big | |
890 | security risk. Take the time to figure out how to do it correctly. | |
891 | .Sh "Can I write useful Perl programs on the command line?" | |
892 | .IX Subsection "Can I write useful Perl programs on the command line?" | |
893 | Yes. Read perlrun for more information. Some examples follow. | |
894 | (These assume standard Unix shell quoting rules.) | |
895 | .PP | |
896 | .Vb 2 | |
897 | \& # sum first and last fields | |
898 | \& perl -lane 'print $F[0] + $F[-1]' * | |
899 | .Ve | |
900 | .PP | |
901 | .Vb 2 | |
902 | \& # identify text files | |
903 | \& perl -le 'for(@ARGV) {print if -f && -T _}' * | |
904 | .Ve | |
905 | .PP | |
906 | .Vb 2 | |
907 | \& # remove (most) comments from C program | |
908 | \& perl -0777 -pe 's{/\e*.*?\e*/}{}gs' foo.c | |
909 | .Ve | |
910 | .PP | |
911 | .Vb 2 | |
912 | \& # make file a month younger than today, defeating reaper daemons | |
913 | \& perl -e '$X=24*60*60; utime(time(),time() + 30 * $X,@ARGV)' * | |
914 | .Ve | |
915 | .PP | |
916 | .Vb 2 | |
917 | \& # find first unused uid | |
918 | \& perl -le '$i++ while getpwuid($i); print $i' | |
919 | .Ve | |
920 | .PP | |
921 | .Vb 3 | |
922 | \& # display reasonable manpath | |
923 | \& echo $PATH | perl -nl -072 -e ' | |
924 | \& s![^/+]*$!man!&&-d&&!$s{$_}++&&push@m,$_;END{print"@m"}' | |
925 | .Ve | |
926 | .PP | |
927 | \&\s-1OK\s0, the last one was actually an Obfuscated Perl Contest entry. :\-) | |
928 | .Sh "Why don't Perl one-liners work on my DOS/Mac/VMS system?" | |
929 | .IX Subsection "Why don't Perl one-liners work on my DOS/Mac/VMS system?" | |
930 | The problem is usually that the command interpreters on those systems | |
931 | have rather different ideas about quoting than the Unix shells under | |
932 | which the one-liners were created. On some systems, you may have to | |
933 | change single-quotes to double ones, which you must \fI\s-1NOT\s0\fR do on Unix | |
934 | or Plan9 systems. You might also have to change a single % to a %%. | |
935 | .PP | |
936 | For example: | |
937 | .PP | |
938 | .Vb 2 | |
939 | \& # Unix | |
940 | \& perl -e 'print "Hello world\en"' | |
941 | .Ve | |
942 | .PP | |
943 | .Vb 2 | |
944 | \& # DOS, etc. | |
945 | \& perl -e "print \e"Hello world\en\e"" | |
946 | .Ve | |
947 | .PP | |
948 | .Vb 3 | |
949 | \& # Mac | |
950 | \& print "Hello world\en" | |
951 | \& (then Run "Myscript" or Shift-Command-R) | |
952 | .Ve | |
953 | .PP | |
954 | .Vb 2 | |
955 | \& # MPW | |
956 | \& perl -e 'print "Hello world\en"' | |
957 | .Ve | |
958 | .PP | |
959 | .Vb 2 | |
960 | \& # VMS | |
961 | \& perl -e "print ""Hello world\en""" | |
962 | .Ve | |
963 | .PP | |
964 | The problem is that none of these examples are reliable: they depend on the | |
965 | command interpreter. Under Unix, the first two often work. Under \s-1DOS\s0, | |
966 | it's entirely possible that neither works. If 4DOS was the command shell, | |
967 | you'd probably have better luck like this: | |
968 | .PP | |
969 | .Vb 1 | |
970 | \& perl -e "print <Ctrl-x>"Hello world\en<Ctrl-x>"" | |
971 | .Ve | |
972 | .PP | |
973 | Under the Mac, it depends which environment you are using. The MacPerl | |
974 | shell, or \s-1MPW\s0, is much like Unix shells in its support for several | |
975 | quoting variants, except that it makes free use of the Mac's non-ASCII | |
976 | characters as control characters. | |
977 | .PP | |
978 | Using \fIqq()\fR, q(), and \fIqx()\fR, instead of \*(L"double quotes\*(R", 'single | |
979 | quotes', and `backticks`, may make one-liners easier to write. | |
980 | .PP | |
981 | There is no general solution to all of this. It is a mess. | |
982 | .PP | |
983 | [Some of this answer was contributed by Kenneth Albanowski.] | |
984 | .Sh "Where can I learn about \s-1CGI\s0 or Web programming in Perl?" | |
985 | .IX Subsection "Where can I learn about CGI or Web programming in Perl?" | |
986 | For modules, get the \s-1CGI\s0 or \s-1LWP\s0 modules from \s-1CPAN\s0. For textbooks, | |
987 | see the two especially dedicated to web stuff in the question on | |
988 | books. For problems and questions related to the web, like ``Why | |
989 | do I get 500 Errors'' or ``Why doesn't it run from the browser right | |
990 | when it runs fine on the command line'', see the troubleshooting | |
991 | guides and references in perlfaq9 or in the \s-1CGI\s0 MetaFAQ: | |
992 | .PP | |
993 | .Vb 1 | |
994 | \& http://www.perl.org/CGI_MetaFAQ.html | |
995 | .Ve | |
996 | .Sh "Where can I learn about object-oriented Perl programming?" | |
997 | .IX Subsection "Where can I learn about object-oriented Perl programming?" | |
998 | A good place to start is perltoot, and you can use perlobj, | |
999 | perlboot, perltoot, perltooc, and perlbot for reference. | |
1000 | (If you are using really old Perl, you may not have all of these, | |
1001 | try http://www.perldoc.com/ , but consider upgrading your perl.) | |
1002 | .PP | |
1003 | A good book on \s-1OO\s0 on Perl is the \*(L"Object\-Oriented Perl\*(R" | |
1004 | by Damian Conway from Manning Publications, | |
1005 | http://www.manning.com/Conway/index.html | |
1006 | .Sh "Where can I learn about linking C with Perl? [h2xs, xsubpp]" | |
1007 | .IX Subsection "Where can I learn about linking C with Perl? [h2xs, xsubpp]" | |
1008 | If you want to call C from Perl, start with perlxstut, | |
1009 | moving on to perlxs, xsubpp, and perlguts. If you want to | |
1010 | call Perl from C, then read perlembed, perlcall, and | |
1011 | perlguts. Don't forget that you can learn a lot from looking at | |
1012 | how the authors of existing extension modules wrote their code and | |
1013 | solved their problems. | |
1014 | .Sh "I've read perlembed, perlguts, etc., but I can't embed perl in my C program; what am I doing wrong?" | |
1015 | .IX Subsection "I've read perlembed, perlguts, etc., but I can't embed perl in my C program; what am I doing wrong?" | |
1016 | Download the ExtUtils::Embed kit from \s-1CPAN\s0 and run `make test'. If | |
1017 | the tests pass, read the pods again and again and again. If they | |
1018 | fail, see perlbug and send a bug report with the output of | |
1019 | \&\f(CW\*(C`make test TEST_VERBOSE=1\*(C'\fR along with \f(CW\*(C`perl \-V\*(C'\fR. | |
1020 | .Sh "When I tried to run my script, I got this message. What does it mean?" | |
1021 | .IX Subsection "When I tried to run my script, I got this message. What does it mean?" | |
1022 | A complete list of Perl's error messages and warnings with explanatory | |
1023 | text can be found in perldiag. You can also use the splain program | |
1024 | (distributed with Perl) to explain the error messages: | |
1025 | .PP | |
1026 | .Vb 2 | |
1027 | \& perl program 2>diag.out | |
1028 | \& splain [-v] [-p] diag.out | |
1029 | .Ve | |
1030 | .PP | |
1031 | or change your program to explain the messages for you: | |
1032 | .PP | |
1033 | .Vb 1 | |
1034 | \& use diagnostics; | |
1035 | .Ve | |
1036 | .PP | |
1037 | or | |
1038 | .PP | |
1039 | .Vb 1 | |
1040 | \& use diagnostics -verbose; | |
1041 | .Ve | |
1042 | .Sh "What's MakeMaker?" | |
1043 | .IX Subsection "What's MakeMaker?" | |
1044 | This module (part of the standard Perl distribution) is designed to | |
1045 | write a Makefile for an extension module from a Makefile.PL. For more | |
1046 | information, see ExtUtils::MakeMaker. | |
1047 | .SH "AUTHOR AND COPYRIGHT" | |
1048 | .IX Header "AUTHOR AND COPYRIGHT" | |
1049 | Copyright (c) 1997\-2002 Tom Christiansen and Nathan Torkington. | |
1050 | All rights reserved. | |
1051 | .PP | |
1052 | This documentation is free; you can redistribute it and/or modify it | |
1053 | under the same terms as Perl itself. | |
1054 | .PP | |
1055 | Irrespective of its distribution, all code examples here are in the public | |
1056 | domain. You are permitted and encouraged to use this code and any | |
1057 | derivatives thereof in your own programs for fun or for profit as you | |
1058 | see fit. A simple comment in the code giving credit to the \s-1FAQ\s0 would | |
1059 | be courteous but is not required. |