Commit | Line | Data |
---|---|---|
04c692a8 | 1 | =encoding utf8 |
35c336e6 | 2 | |
04c692a8 DR |
3 | =for comment |
4 | Consistent formatting of this file is achieved with: | |
5 | perl ./Porting/podtidy pod/perlhack.pod | |
35c336e6 | 6 | |
04c692a8 | 7 | =head1 NAME |
35c336e6 | 8 | |
04c692a8 | 9 | perlhack - How to hack on Perl |
35c336e6 | 10 | |
04c692a8 | 11 | =head1 DESCRIPTION |
35c336e6 | 12 | |
04c692a8 DR |
13 | This document explains how Perl development works. It includes details |
14 | about the Perl 5 Porters email list, the Perl repository, the Perlbug | |
15 | bug tracker, patch guidelines, and commentary on Perl development | |
16 | philosophy. | |
f7e1e956 | 17 | |
04c692a8 | 18 | =head1 SUPER QUICK PATCH GUIDE |
f7e1e956 | 19 | |
04c692a8 DR |
20 | If you just want to submit a single small patch like a pod fix, a test |
21 | for a bug, comment fixes, etc., it's easy! Here's how: | |
f7e1e956 | 22 | |
04c692a8 | 23 | =over 4 |
e018f8be | 24 | |
04c692a8 | 25 | =item * Check out the source repository |
e018f8be | 26 | |
04c692a8 DR |
27 | The perl source is in a git repository. You can clone the repository |
28 | with the following command: | |
e018f8be | 29 | |
04c692a8 | 30 | % git clone git://perl5.git.perl.org/perl.git perl |
e018f8be | 31 | |
04c692a8 | 32 | =item * Make your change |
e018f8be | 33 | |
04c692a8 | 34 | Hack, hack, hack. |
7205a85d | 35 | |
04c692a8 | 36 | =item * Test your change |
e018f8be | 37 | |
04c692a8 | 38 | You can run all the tests with the following commands: |
b26492ee | 39 | |
04c692a8 DR |
40 | % ./Configure -des -Dusedevel |
41 | % make test | |
7205a85d | 42 | |
04c692a8 | 43 | Keep hacking until the tests pass. |
b26492ee | 44 | |
04c692a8 | 45 | =item * Commit your change |
e018f8be | 46 | |
b6538e4f | 47 | Committing your work will save the change I<on your local system>: |
7205a85d | 48 | |
04c692a8 | 49 | % git commit -a -m 'Commit message goes here' |
e018f8be | 50 | |
04c692a8 DR |
51 | Make sure the commit message describes your change in a single |
52 | sentence. For example, "Fixed spelling errors in perlhack.pod". | |
e018f8be | 53 | |
04c692a8 | 54 | =item * Send your change to perlbug |
7a834142 | 55 | |
04c692a8 DR |
56 | The next step is to submit your patch to the Perl core ticket system |
57 | via email. | |
7a834142 | 58 | |
5c70016e JC |
59 | Assuming your patch consists of a single git commit, the following |
60 | writes the file as a MIME attachment, and sends it with a meaningful | |
61 | subject: | |
e018f8be | 62 | |
5c70016e | 63 | % git format-patch -1 --attach |
d23ed4f3 | 64 | % perlbug -s "[PATCH] $(git log -1 --oneline HEAD)" -f 0001-*.patch |
e018f8be | 65 | |
04c692a8 DR |
66 | The perlbug program will ask you a few questions about your email |
67 | address and the patch you're submitting. Once you've answered them you | |
68 | can submit your patch. | |
e018f8be | 69 | |
04c692a8 | 70 | =item * Thank you |
e018f8be | 71 | |
04c692a8 DR |
72 | The porters appreciate the time you spent helping to make Perl better. |
73 | Thank you! | |
e018f8be | 74 | |
cce04beb | 75 | =back |
e018f8be | 76 | |
04c692a8 | 77 | =head1 BUG REPORTING |
cc0710ff | 78 | |
a8d15a22 | 79 | If you want to report a bug in Perl, you must use the F<perlbug> command |
04c692a8 DR |
80 | line tool. This tool will ensure that your bug report includes all the |
81 | relevant system and configuration information. | |
7205a85d | 82 | |
04c692a8 | 83 | To browse existing Perl bugs and patches, you can use the web interface |
a8d15a22 | 84 | at L<http://rt.perl.org/>. |
244d9cb7 | 85 | |
04c692a8 DR |
86 | Please check the archive of the perl5-porters list (see below) and/or |
87 | the bug tracking system before submitting a bug report. Often, you'll | |
88 | find that the bug has been reported already. | |
244d9cb7 | 89 | |
04c692a8 DR |
90 | You can log in to the bug tracking system and comment on existing bug |
91 | reports. If you have additional information regarding an existing bug, | |
92 | please add it. This will help the porters fix the bug. | |
7205a85d | 93 | |
04c692a8 | 94 | =head1 PERL 5 PORTERS |
7205a85d | 95 | |
04c692a8 DR |
96 | The perl5-porters (p5p) mailing list is where the Perl standard |
97 | distribution is maintained and developed. The people who maintain Perl | |
98 | are also referred to as the "Perl 5 Porters", or just the "porters". | |
a75f557c | 99 | |
04c692a8 DR |
100 | A searchable archive of the list is available at |
101 | L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/>. There is | |
102 | also another archive at | |
103 | L<http://archive.develooper.com/perl5-porters@perl.org/>. | |
7205a85d | 104 | |
04c692a8 | 105 | =head2 perl-changes mailing list |
7205a85d | 106 | |
04c692a8 DR |
107 | The perl5-changes mailing list receives a copy of each patch that gets |
108 | submitted to the maintenance and development branches of the perl | |
109 | repository. See L<http://lists.perl.org/list/perl5-changes.html> for | |
110 | subscription and archive information. | |
244d9cb7 | 111 | |
04c692a8 | 112 | =head1 GETTING THE PERL SOURCE |
244d9cb7 | 113 | |
04c692a8 DR |
114 | All of Perl's source code is kept centrally in a Git repository at |
115 | I<perl5.git.perl.org>. The repository contains many Perl revisions from | |
116 | Perl 1 onwards and all the revisions from Perforce, the previous | |
117 | version control system. | |
244d9cb7 | 118 | |
04c692a8 DR |
119 | For much more detail on using git with the Perl repository, please see |
120 | L<perlgit>. | |
244d9cb7 | 121 | |
04c692a8 | 122 | =head2 Read access via Git |
244d9cb7 | 123 | |
04c692a8 DR |
124 | You will need a copy of Git for your computer. You can fetch a copy of |
125 | the repository using the git protocol: | |
244d9cb7 | 126 | |
04c692a8 | 127 | % git clone git://perl5.git.perl.org/perl.git perl |
244d9cb7 | 128 | |
04c692a8 DR |
129 | This clones the repository and makes a local copy in the F<perl> |
130 | directory. | |
7205a85d | 131 | |
04c692a8 DR |
132 | If you cannot use the git protocol for firewall reasons, you can also |
133 | clone via http, though this is much slower: | |
7205a85d | 134 | |
04c692a8 | 135 | % git clone http://perl5.git.perl.org/perl.git perl |
7205a85d | 136 | |
04c692a8 | 137 | =head2 Read access via the web |
7205a85d | 138 | |
04c692a8 DR |
139 | You may access the repository over the web. This allows you to browse |
140 | the tree, see recent commits, subscribe to RSS feeds for the changes, | |
141 | search for particular commits and more. You may access it at | |
142 | L<http://perl5.git.perl.org/perl.git>. A mirror of the repository is | |
a8d15a22 | 143 | found at L<http://github.com/mirrors/perl>. |
7205a85d | 144 | |
04c692a8 | 145 | =head2 Read access via rsync |
7205a85d | 146 | |
04c692a8 DR |
147 | You can also choose to use rsync to get a copy of the current source |
148 | tree for the bleadperl branch and all maintenance branches: | |
7205a85d | 149 | |
efdea7e2 R |
150 | % rsync -avz rsync://perl5.git.perl.org/perl-current . |
151 | % rsync -avz rsync://perl5.git.perl.org/perl-5.12.x . | |
152 | % rsync -avz rsync://perl5.git.perl.org/perl-5.10.x . | |
153 | % rsync -avz rsync://perl5.git.perl.org/perl-5.8.x . | |
154 | % rsync -avz rsync://perl5.git.perl.org/perl-5.6.x . | |
155 | % rsync -avz rsync://perl5.git.perl.org/perl-5.005xx . | |
7205a85d | 156 | |
a8d15a22 | 157 | (Add the C<--delete> option to remove leftover files.) |
7205a85d | 158 | |
04c692a8 | 159 | To get a full list of the available sync points: |
7205a85d | 160 | |
efdea7e2 | 161 | % rsync perl5.git.perl.org:: |
7205a85d | 162 | |
04c692a8 | 163 | =head2 Write access via git |
7205a85d | 164 | |
04c692a8 DR |
165 | If you have a commit bit, please see L<perlgit> for more details on |
166 | using git. | |
7205a85d | 167 | |
04c692a8 | 168 | =head1 PATCHING PERL |
7205a85d | 169 | |
04c692a8 DR |
170 | If you're planning to do more extensive work than a single small fix, |
171 | we encourage you to read the documentation below. This will help you | |
172 | focus your work and make your patches easier to incorporate into the | |
173 | Perl source. | |
244d9cb7 | 174 | |
04c692a8 | 175 | =head2 Submitting patches |
244d9cb7 | 176 | |
04c692a8 DR |
177 | If you have a small patch to submit, please submit it via perlbug. You |
178 | can also send email directly to perlbug@perl.org. Please note that | |
179 | messages sent to perlbug may be held in a moderation queue, so you | |
180 | won't receive a response immediately. | |
244d9cb7 | 181 | |
04c692a8 DR |
182 | You'll know your submission has been processed when you receive an |
183 | email from our ticket tracking system. This email will give you a | |
184 | ticket number. Once your patch has made it to the ticket tracking | |
185 | system, it will also be sent to the perl5-porters@perl.org list. | |
244d9cb7 | 186 | |
04c692a8 DR |
187 | Patches are reviewed and discussed on the p5p list. Simple, |
188 | uncontroversial patches will usually be applied without any discussion. | |
189 | When the patch is applied, the ticket will be updated and you will | |
190 | receive email. In addition, an email will be sent to the p5p list. | |
244d9cb7 | 191 | |
04c692a8 DR |
192 | In other cases, the patch will need more work or discussion. That will |
193 | happen on the p5p list. | |
244d9cb7 | 194 | |
04c692a8 DR |
195 | You are encouraged to participate in the discussion and advocate for |
196 | your patch. Sometimes your patch may get lost in the shuffle. It's | |
197 | appropriate to send a reminder email to p5p if no action has been taken | |
198 | in a month. Please remember that the Perl 5 developers are all | |
199 | volunteers, and be polite. | |
244d9cb7 | 200 | |
04c692a8 DR |
201 | Changes are always applied directly to the main development branch, |
202 | called "blead". Some patches may be backported to a maintenance branch. | |
203 | If you think your patch is appropriate for the maintenance branch, | |
204 | please explain why when you submit it. | |
244d9cb7 | 205 | |
04c692a8 | 206 | =head2 Getting your patch accepted |
244d9cb7 | 207 | |
04c692a8 DR |
208 | If you are submitting a code patch there are several things that you |
209 | can do to help the Perl 5 Porters accept your patch. | |
244d9cb7 | 210 | |
a126fb62 DR |
211 | =head3 Patch style |
212 | ||
213 | If you used git to check out the Perl source, then using C<git | |
214 | format-patch> will produce a patch in a style suitable for Perl. The | |
215 | C<format-patch> command produces one patch file for each commit you | |
216 | made. If you prefer to send a single patch for all commits, you can use | |
217 | C<git diff>. | |
218 | ||
9d440a18 | 219 | % git checkout blead |
a126fb62 DR |
220 | % git pull |
221 | % git diff blead my-branch-name | |
222 | ||
223 | This produces a patch based on the difference between blead and your | |
224 | current branch. It's important to make sure that blead is up to date | |
225 | before producing the diff, that's why we call C<git pull> first. | |
226 | ||
227 | We strongly recommend that you use git if possible. It will make your | |
228 | life easier, and ours as well. | |
229 | ||
230 | However, if you're not using git, you can still produce a suitable | |
231 | patch. You'll need a pristine copy of the Perl source to diff against. | |
232 | The porters prefer unified diffs. Using GNU C<diff>, you can produce a | |
233 | diff like this: | |
234 | ||
235 | % diff -Npurd perl.pristine perl.mine | |
236 | ||
237 | Make sure that you C<make realclean> in your copy of Perl to remove any | |
238 | build artifacts, or you may get a confusing result. | |
239 | ||
04c692a8 | 240 | =head3 Commit message |
244d9cb7 | 241 | |
04c692a8 DR |
242 | As you craft each patch you intend to submit to the Perl core, it's |
243 | important to write a good commit message. This is especially important | |
244 | if your submission will consist of a series of commits. | |
244d9cb7 | 245 | |
04c692a8 DR |
246 | The first line of the commit message should be a short description |
247 | without a period. It should be no longer than the subject line of an | |
a8d15a22 | 248 | email, 50 characters being a good rule of thumb. |
f7e1e956 | 249 | |
a8d15a22 | 250 | A lot of Git tools (Gitweb, GitHub, git log --pretty=oneline, ...) will |
04c692a8 DR |
251 | only display the first line (cut off at 50 characters) when presenting |
252 | commit summaries. | |
7cd58830 | 253 | |
04c692a8 DR |
254 | The commit message should include a description of the problem that the |
255 | patch corrects or new functionality that the patch adds. | |
7cd58830 | 256 | |
04c692a8 DR |
257 | As a general rule of thumb, your commit message should help a |
258 | programmer who knows the Perl core quickly understand what you were | |
259 | trying to do, how you were trying to do it, and why the change matters | |
260 | to Perl. | |
7cd58830 | 261 | |
04c692a8 | 262 | =over 4 |
7cd58830 | 263 | |
04c692a8 | 264 | =item * Why |
7cd58830 | 265 | |
04c692a8 DR |
266 | Your commit message should describe why the change you are making is |
267 | important. When someone looks at your change in six months or six | |
268 | years, your intent should be clear. | |
7cd58830 | 269 | |
04c692a8 DR |
270 | If you're deprecating a feature with the intent of later simplifying |
271 | another bit of code, say so. If you're fixing a performance problem or | |
272 | adding a new feature to support some other bit of the core, mention | |
273 | that. | |
7cd58830 | 274 | |
04c692a8 | 275 | =item * What |
7cd58830 | 276 | |
04c692a8 DR |
277 | Your commit message should describe what part of the Perl core you're |
278 | changing and what you expect your patch to do. | |
7cd58830 | 279 | |
04c692a8 | 280 | =item * How |
7cd58830 | 281 | |
04c692a8 DR |
282 | While it's not necessary for documentation changes, new tests or |
283 | trivial patches, it's often worth explaining how your change works. | |
284 | Even if it's clear to you today, it may not be clear to a porter next | |
285 | month or next year. | |
d7889f52 | 286 | |
04c692a8 | 287 | =back |
d7889f52 | 288 | |
04c692a8 DR |
289 | A commit message isn't intended to take the place of comments in your |
290 | code. Commit messages should describe the change you made, while code | |
291 | comments should describe the current state of the code. | |
d7889f52 | 292 | |
04c692a8 DR |
293 | If you've just implemented a new feature, complete with doc, tests and |
294 | well-commented code, a brief commit message will often suffice. If, | |
295 | however, you've just changed a single character deep in the parser or | |
296 | lexer, you might need to write a small novel to ensure that future | |
297 | readers understand what you did and why you did it. | |
d7889f52 | 298 | |
04c692a8 | 299 | =head3 Comments, Comments, Comments |
d7889f52 | 300 | |
04c692a8 DR |
301 | Be sure to adequately comment your code. While commenting every line is |
302 | unnecessary, anything that takes advantage of side effects of | |
303 | operators, that creates changes that will be felt outside of the | |
304 | function being patched, or that others may find confusing should be | |
305 | documented. If you are going to err, it is better to err on the side of | |
306 | adding too many comments than too few. | |
d7889f52 | 307 | |
04c692a8 DR |
308 | The best comments explain I<why> the code does what it does, not I<what |
309 | it does>. | |
d7889f52 | 310 | |
04c692a8 | 311 | =head3 Style |
d7889f52 | 312 | |
04c692a8 DR |
313 | In general, please follow the particular style of the code you are |
314 | patching. | |
d7889f52 | 315 | |
04c692a8 DR |
316 | In particular, follow these general guidelines for patching Perl |
317 | sources: | |
cce04beb | 318 | |
04c692a8 | 319 | =over 4 |
d7889f52 JH |
320 | |
321 | =item * | |
322 | ||
04c692a8 | 323 | 8-wide tabs (no exceptions!) |
d7889f52 JH |
324 | |
325 | =item * | |
326 | ||
04c692a8 | 327 | 4-wide indents for code, 2-wide indents for nested CPP #defines |
ee9468a2 | 328 | |
cce04beb | 329 | =item * |
ee9468a2 | 330 | |
04c692a8 | 331 | Try hard not to exceed 79-columns |
bc028b6b | 332 | |
ee9468a2 RGS |
333 | =item * |
334 | ||
04c692a8 | 335 | ANSI C prototypes |
d7889f52 JH |
336 | |
337 | =item * | |
338 | ||
04c692a8 | 339 | Uncuddled elses and "K&R" style for indenting control constructs |
0bec6c03 | 340 | |
04c692a8 | 341 | =item * |
d7889f52 | 342 | |
04c692a8 | 343 | No C++ style (//) comments |
d7889f52 JH |
344 | |
345 | =item * | |
346 | ||
04c692a8 | 347 | Mark places that need to be revisited with XXX (and revisit often!) |
27565cb6 JH |
348 | |
349 | =item * | |
350 | ||
04c692a8 DR |
351 | Opening brace lines up with "if" when conditional spans multiple lines; |
352 | should be at end-of-line otherwise | |
27565cb6 | 353 | |
04c692a8 | 354 | =item * |
27565cb6 | 355 | |
04c692a8 DR |
356 | In function definitions, name starts in column 0 (return value is on |
357 | previous line) | |
27565cb6 | 358 | |
04c692a8 | 359 | =item * |
27565cb6 | 360 | |
04c692a8 DR |
361 | Single space after keywords that are followed by parens, no space |
362 | between function name and following paren | |
606fd33d | 363 | |
27565cb6 JH |
364 | =item * |
365 | ||
04c692a8 DR |
366 | Avoid assignments in conditionals, but if they're unavoidable, use |
367 | extra paren, e.g. "if (a && (b = c)) ..." | |
27565cb6 JH |
368 | |
369 | =item * | |
370 | ||
04c692a8 | 371 | "return foo;" rather than "return(foo);" |
27565cb6 JH |
372 | |
373 | =item * | |
374 | ||
04c692a8 | 375 | "if (!foo) ..." rather than "if (foo == FALSE) ..." etc. |
606fd33d JH |
376 | |
377 | =back | |
27565cb6 | 378 | |
04c692a8 | 379 | =head3 Test suite |
d7889f52 | 380 | |
a8d15a22 | 381 | If your patch changes code (rather than just changing documentation), |
04c692a8 DR |
382 | you should also include one or more test cases which illustrate the bug |
383 | you're fixing or validate the new functionality you're adding. In | |
384 | general, you should update an existing test file rather than create a | |
385 | new one. | |
2bbc8d55 | 386 | |
04c692a8 DR |
387 | Your test suite additions should generally follow these guidelines |
388 | (courtesy of Gurusamy Sarathy <gsar@activestate.com>): | |
2bbc8d55 | 389 | |
04c692a8 | 390 | =over 4 |
0bec6c03 | 391 | |
04c692a8 | 392 | =item * |
0bec6c03 | 393 | |
04c692a8 | 394 | Know what you're testing. Read the docs, and the source. |
ee9468a2 RGS |
395 | |
396 | =item * | |
397 | ||
04c692a8 | 398 | Tend to fail, not succeed. |
0bec6c03 | 399 | |
04c692a8 | 400 | =item * |
0bec6c03 | 401 | |
04c692a8 | 402 | Interpret results strictly. |
27565cb6 | 403 | |
04c692a8 | 404 | =item * |
27565cb6 | 405 | |
04c692a8 | 406 | Use unrelated features (this will flush out bizarre interactions). |
27565cb6 | 407 | |
04c692a8 | 408 | =item * |
27565cb6 | 409 | |
04c692a8 | 410 | Use non-standard idioms (otherwise you are not testing TIMTOWTDI). |
27565cb6 | 411 | |
04c692a8 | 412 | =item * |
d7889f52 | 413 | |
04c692a8 DR |
414 | Avoid using hardcoded test numbers whenever possible (the EXPECTED/GOT |
415 | found in t/op/tie.t is much more maintainable, and gives better failure | |
416 | reports). | |
d7889f52 | 417 | |
04c692a8 | 418 | =item * |
d7889f52 | 419 | |
04c692a8 | 420 | Give meaningful error messages when a test fails. |
d7889f52 | 421 | |
04c692a8 | 422 | =item * |
d7889f52 | 423 | |
04c692a8 DR |
424 | Avoid using qx// and system() unless you are testing for them. If you |
425 | do use them, make sure that you cover _all_ perl platforms. | |
d7889f52 | 426 | |
04c692a8 | 427 | =item * |
0bec6c03 | 428 | |
04c692a8 | 429 | Unlink any temporary files you create. |
63796a85 | 430 | |
04c692a8 | 431 | =item * |
0bec6c03 | 432 | |
04c692a8 | 433 | Promote unforeseen warnings to errors with $SIG{__WARN__}. |
0bec6c03 | 434 | |
04c692a8 | 435 | =item * |
0bec6c03 | 436 | |
04c692a8 DR |
437 | Be sure to use the libraries and modules shipped with the version being |
438 | tested, not those that were already installed. | |
d7889f52 | 439 | |
04c692a8 | 440 | =item * |
d7889f52 | 441 | |
04c692a8 | 442 | Add comments to the code explaining what you are testing for. |
d7889f52 | 443 | |
04c692a8 | 444 | =item * |
d7889f52 | 445 | |
04c692a8 DR |
446 | Make updating the '1..42' string unnecessary. Or make sure that you |
447 | update it. | |
d7889f52 | 448 | |
04c692a8 | 449 | =item * |
d7889f52 | 450 | |
04c692a8 | 451 | Test _all_ behaviors of a given operator, library, or function. |
d7889f52 | 452 | |
04c692a8 | 453 | Test all optional arguments. |
d7889f52 | 454 | |
04c692a8 | 455 | Test return values in various contexts (boolean, scalar, list, lvalue). |
d7889f52 | 456 | |
04c692a8 | 457 | Use both global and lexical variables. |
d7889f52 | 458 | |
04c692a8 | 459 | Don't forget the exceptional, pathological cases. |
0bec6c03 | 460 | |
cce04beb | 461 | =back |
0bec6c03 | 462 | |
04c692a8 | 463 | =head2 Patching a core module |
ee9468a2 | 464 | |
04c692a8 DR |
465 | This works just like patching anything else, with one extra |
466 | consideration. | |
63796a85 | 467 | |
a8d15a22 | 468 | Modules in the F<cpan/> directory of the source tree are maintained |
24b68a05 DG |
469 | outside of the Perl core. When the author updates the module, the |
470 | updates are simply copied into the core. See that module's | |
471 | documentation or its listing on L<http://search.cpan.org/> for more | |
472 | information on reporting bugs and submitting patches. | |
473 | ||
474 | In most cases, patches to modules in F<cpan/> should be sent upstream | |
7e5887a1 DG |
475 | and should not be applied to the Perl core individually. If a patch |
476 | to a file in F<cpan/> absolutely cannot wait for the fix to be made | |
477 | upstream, released to CPAN and copied to blead, you must add (or | |
478 | update) a C<CUSTOMIZED> entry in the F<"Porting/Maintainers.pl"> file | |
479 | to flag that a local modification has been made. See | |
480 | F<"Porting/Maintainers.pl"> for more details. | |
63796a85 | 481 | |
04c692a8 DR |
482 | In contrast, modules in the F<dist/> directory are maintained in the |
483 | core. | |
63796a85 | 484 | |
04c692a8 | 485 | =head2 Updating perldelta |
63796a85 | 486 | |
04c692a8 DR |
487 | For changes significant enough to warrant a F<pod/perldelta.pod> entry, |
488 | the porters will greatly appreciate it if you submit a delta entry | |
489 | along with your actual change. Significant changes include, but are not | |
490 | limited to: | |
63796a85 | 491 | |
04c692a8 | 492 | =over 4 |
63796a85 | 493 | |
04c692a8 | 494 | =item * |
63796a85 | 495 | |
04c692a8 | 496 | Adding, deprecating, or removing core features |
ee9468a2 | 497 | |
04c692a8 | 498 | =item * |
ee9468a2 | 499 | |
04c692a8 | 500 | Adding, deprecating, removing, or upgrading core or dual-life modules |
ee9468a2 | 501 | |
04c692a8 | 502 | =item * |
ee9468a2 | 503 | |
04c692a8 | 504 | Adding new core tests |
ee9468a2 | 505 | |
04c692a8 | 506 | =item * |
ee9468a2 | 507 | |
04c692a8 | 508 | Fixing security issues and user-visible bugs in the core |
cce04beb | 509 | |
04c692a8 | 510 | =item * |
ad7244db | 511 | |
04c692a8 | 512 | Changes that might break existing code, either on the perl or C level |
ad7244db JH |
513 | |
514 | =item * | |
515 | ||
04c692a8 | 516 | Significant performance improvements |
ad7244db JH |
517 | |
518 | =item * | |
519 | ||
04c692a8 DR |
520 | Adding, removing, or significantly changing documentation in the |
521 | F<pod/> directory | |
ad7244db | 522 | |
cce04beb | 523 | =item * |
ad7244db | 524 | |
04c692a8 | 525 | Important platform-specific changes |
d7889f52 | 526 | |
cce04beb DG |
527 | =back |
528 | ||
04c692a8 DR |
529 | Please make sure you add the perldelta entry to the right section |
530 | within F<pod/perldelta.pod>. More information on how to write good | |
531 | perldelta entries is available in the C<Style> section of | |
532 | F<Porting/how_to_write_a_perldelta.pod>. | |
d7889f52 | 533 | |
04c692a8 | 534 | =head2 What makes for a good patch? |
d7889f52 | 535 | |
04c692a8 DR |
536 | New features and extensions to the language can be contentious. There |
537 | is no specific set of criteria which determine what features get added, | |
538 | but here are some questions to consider when developing a patch: | |
d7889f52 | 539 | |
04c692a8 | 540 | =head3 Does the concept match the general goals of Perl? |
d7889f52 | 541 | |
04c692a8 | 542 | Our goals include, but are not limited to: |
d7889f52 | 543 | |
04c692a8 | 544 | =over 4 |
d7889f52 | 545 | |
04c692a8 | 546 | =item 1. |
d7889f52 | 547 | |
04c692a8 | 548 | Keep it fast, simple, and useful. |
cce04beb | 549 | |
04c692a8 | 550 | =item 2. |
cce04beb | 551 | |
04c692a8 | 552 | Keep features/concepts as orthogonal as possible. |
902b9dbf | 553 | |
04c692a8 | 554 | =item 3. |
902b9dbf | 555 | |
04c692a8 | 556 | No arbitrary limits (platforms, data sizes, cultures). |
a958818a | 557 | |
04c692a8 | 558 | =item 4. |
ac036724 | 559 | |
04c692a8 | 560 | Keep it open and exciting to use/patch/advocate Perl everywhere. |
a958818a | 561 | |
04c692a8 | 562 | =item 5. |
a958818a | 563 | |
04c692a8 | 564 | Either assimilate new technologies, or build bridges to them. |
a958818a | 565 | |
04c692a8 | 566 | =back |
a958818a | 567 | |
04c692a8 | 568 | =head3 Where is the implementation? |
a958818a | 569 | |
04c692a8 DR |
570 | All the talk in the world is useless without an implementation. In |
571 | almost every case, the person or people who argue for a new feature | |
572 | will be expected to be the ones who implement it. Porters capable of | |
573 | coding new features have their own agendas, and are not available to | |
574 | implement your (possibly good) idea. | |
a1b65709 | 575 | |
04c692a8 | 576 | =head3 Backwards compatibility |
37c0adeb | 577 | |
04c692a8 DR |
578 | It's a cardinal sin to break existing Perl programs. New warnings can |
579 | be contentious--some say that a program that emits warnings is not | |
580 | broken, while others say it is. Adding keywords has the potential to | |
581 | break programs, changing the meaning of existing token sequences or | |
582 | functions might break programs. | |
f50e5b73 | 583 | |
04c692a8 DR |
584 | The Perl 5 core includes mechanisms to help porters make backwards |
585 | incompatible changes more compatible such as the L<feature> and | |
586 | L<deprecate> modules. Please use them when appropriate. | |
902b9dbf | 587 | |
04c692a8 | 588 | =head3 Could it be a module instead? |
902b9dbf | 589 | |
04c692a8 DR |
590 | Perl 5 has extension mechanisms, modules and XS, specifically to avoid |
591 | the need to keep changing the Perl interpreter. You can write modules | |
592 | that export functions, you can give those functions prototypes so they | |
593 | can be called like built-in functions, you can even write XS code to | |
594 | mess with the runtime data structures of the Perl interpreter if you | |
595 | want to implement really complicated things. | |
902b9dbf | 596 | |
04c692a8 DR |
597 | Whenever possible, new features should be prototyped in a CPAN module |
598 | before they will be considered for the core. | |
902b9dbf | 599 | |
04c692a8 | 600 | =head3 Is the feature generic enough? |
902b9dbf | 601 | |
04c692a8 DR |
602 | Is this something that only the submitter wants added to the language, |
603 | or is it broadly useful? Sometimes, instead of adding a feature with a | |
604 | tight focus, the porters might decide to wait until someone implements | |
605 | the more generalized feature. | |
902b9dbf | 606 | |
04c692a8 | 607 | =head3 Does it potentially introduce new bugs? |
902b9dbf | 608 | |
04c692a8 DR |
609 | Radical rewrites of large chunks of the Perl interpreter have the |
610 | potential to introduce new bugs. | |
902b9dbf | 611 | |
04c692a8 | 612 | =head3 How big is it? |
902b9dbf | 613 | |
04c692a8 DR |
614 | The smaller and more localized the change, the better. Similarly, a |
615 | series of small patches is greatly preferred over a single large patch. | |
902b9dbf | 616 | |
04c692a8 | 617 | =head3 Does it preclude other desirable features? |
902b9dbf | 618 | |
04c692a8 DR |
619 | A patch is likely to be rejected if it closes off future avenues of |
620 | development. For instance, a patch that placed a true and final | |
621 | interpretation on prototypes is likely to be rejected because there are | |
622 | still options for the future of prototypes that haven't been addressed. | |
902b9dbf | 623 | |
04c692a8 | 624 | =head3 Is the implementation robust? |
902b9dbf | 625 | |
04c692a8 DR |
626 | Good patches (tight code, complete, correct) stand more chance of going |
627 | in. Sloppy or incorrect patches might be placed on the back burner | |
628 | until the pumpking has time to fix, or might be discarded altogether | |
629 | without further notice. | |
902b9dbf | 630 | |
04c692a8 | 631 | =head3 Is the implementation generic enough to be portable? |
902b9dbf | 632 | |
a8d15a22 | 633 | The worst patches make use of system-specific features. It's highly |
04c692a8 DR |
634 | unlikely that non-portable additions to the Perl language will be |
635 | accepted. | |
902b9dbf | 636 | |
04c692a8 | 637 | =head3 Is the implementation tested? |
902b9dbf | 638 | |
04c692a8 DR |
639 | Patches which change behaviour (fixing bugs or introducing new |
640 | features) must include regression tests to verify that everything works | |
641 | as expected. | |
902b9dbf | 642 | |
04c692a8 DR |
643 | Without tests provided by the original author, how can anyone else |
644 | changing perl in the future be sure that they haven't unwittingly | |
645 | broken the behaviour the patch implements? And without tests, how can | |
646 | the patch's author be confident that his/her hard work put into the | |
647 | patch won't be accidentally thrown away by someone in the future? | |
902b9dbf | 648 | |
04c692a8 | 649 | =head3 Is there enough documentation? |
902b9dbf | 650 | |
04c692a8 DR |
651 | Patches without documentation are probably ill-thought out or |
652 | incomplete. No features can be added or changed without documentation, | |
653 | so submitting a patch for the appropriate pod docs as well as the | |
654 | source code is important. | |
902b9dbf | 655 | |
04c692a8 | 656 | =head3 Is there another way to do it? |
902b9dbf | 657 | |
04c692a8 DR |
658 | Larry said "Although the Perl Slogan is I<There's More Than One Way to |
659 | Do It>, I hesitate to make 10 ways to do something". This is a tricky | |
660 | heuristic to navigate, though--one man's essential addition is another | |
661 | man's pointless cruft. | |
902b9dbf | 662 | |
04c692a8 | 663 | =head3 Does it create too much work? |
902b9dbf | 664 | |
04c692a8 DR |
665 | Work for the pumpking, work for Perl programmers, work for module |
666 | authors, ... Perl is supposed to be easy. | |
902b9dbf | 667 | |
04c692a8 | 668 | =head3 Patches speak louder than words |
902b9dbf | 669 | |
04c692a8 DR |
670 | Working code is always preferred to pie-in-the-sky ideas. A patch to |
671 | add a feature stands a much higher chance of making it to the language | |
672 | than does a random feature request, no matter how fervently argued the | |
673 | request might be. This ties into "Will it be useful?", as the fact that | |
674 | someone took the time to make the patch demonstrates a strong desire | |
675 | for the feature. | |
c406981e | 676 | |
04c692a8 | 677 | =head1 TESTING |
c406981e | 678 | |
04c692a8 DR |
679 | The core uses the same testing style as the rest of Perl, a simple |
680 | "ok/not ok" run through Test::Harness, but there are a few special | |
681 | considerations. | |
c406981e | 682 | |
04c692a8 DR |
683 | There are three ways to write a test in the core. L<Test::More>, |
684 | F<t/test.pl> and ad hoc C<print $test ? "ok 42\n" : "not ok 42\n">. The | |
685 | decision of which to use depends on what part of the test suite you're | |
686 | working on. This is a measure to prevent a high-level failure (such as | |
687 | Config.pm breaking) from causing basic functionality tests to fail. | |
c406981e | 688 | |
04c692a8 DR |
689 | The F<t/test.pl> library provides some of the features of |
690 | L<Test::More>, but avoids loading most modules and uses as few core | |
691 | features as possible. | |
902b9dbf | 692 | |
d5d573ba | 693 | If you write your own test, use the L<Test Anything Protocol|http://testanything.org>. |
902b9dbf MLF |
694 | |
695 | =over 4 | |
696 | ||
04c692a8 | 697 | =item * F<t/base> and F<t/comp> |
902b9dbf | 698 | |
04c692a8 DR |
699 | Since we don't know if require works, or even subroutines, use ad hoc |
700 | tests for these two. Step carefully to avoid using the feature being | |
701 | tested. | |
902b9dbf | 702 | |
a8d15a22 | 703 | =item * F<t/cmd>, F<t/run>, F<t/io> and F<t/op> |
902b9dbf | 704 | |
04c692a8 DR |
705 | Now that basic require() and subroutines are tested, you can use the |
706 | F<t/test.pl> library. | |
902b9dbf | 707 | |
a8d15a22 | 708 | You can also use certain libraries like Config conditionally, but be |
04c692a8 | 709 | sure to skip the test gracefully if it's not there. |
902b9dbf | 710 | |
04c692a8 | 711 | =item * Everything else |
902b9dbf | 712 | |
04c692a8 DR |
713 | Now that the core of Perl is tested, L<Test::More> can and should be |
714 | used. You can also use the full suite of core modules in the tests. | |
902b9dbf MLF |
715 | |
716 | =back | |
717 | ||
a8d15a22 R |
718 | When you say "make test", Perl uses the F<t/TEST> program to run the |
719 | test suite (except under Win32 where it uses F<t/harness> instead). All | |
04c692a8 DR |
720 | tests are run from the F<t/> directory, B<not> the directory which |
721 | contains the test. This causes some problems with the tests in F<lib/>, | |
722 | so here's some opportunity for some patching. | |
902b9dbf | 723 | |
04c692a8 DR |
724 | You must be triply conscious of cross-platform concerns. This usually |
725 | boils down to using L<File::Spec> and avoiding things like C<fork()> | |
726 | and C<system()> unless absolutely necessary. | |
7a834142 | 727 | |
04c692a8 | 728 | =head2 Special C<make test> targets |
07aa3531 | 729 | |
04c692a8 DR |
730 | There are various special make targets that can be used to test Perl |
731 | slightly differently than the standard "test" target. Not all them are | |
732 | expected to give a 100% success rate. Many of them have several | |
733 | aliases, and many of them are not available on certain operating | |
734 | systems. | |
07aa3531 | 735 | |
04c692a8 | 736 | =over 4 |
d44161bf | 737 | |
04c692a8 | 738 | =item * test_porting |
7a834142 | 739 | |
04c692a8 DR |
740 | This runs some basic sanity tests on the source tree and helps catch |
741 | basic errors before you submit a patch. | |
7a834142 | 742 | |
04c692a8 | 743 | =item * coretest |
7a834142 | 744 | |
04c692a8 | 745 | Run F<perl> on all core tests (F<t/*> and F<lib/[a-z]*> pragma tests). |
09187cb1 | 746 | |
04c692a8 | 747 | (Not available on Win32) |
09187cb1 | 748 | |
04c692a8 | 749 | =item * test.deparse |
09187cb1 | 750 | |
04c692a8 | 751 | Run all the tests through L<B::Deparse>. Not all tests will succeed. |
64cea5fd | 752 | |
04c692a8 | 753 | (Not available on Win32) |
64cea5fd | 754 | |
04c692a8 | 755 | =item * test.taintwarn |
64cea5fd | 756 | |
04c692a8 DR |
757 | Run all tests with the B<-t> command-line switch. Not all tests are |
758 | expected to succeed (until they're specifically fixed, of course). | |
51a35ef1 | 759 | |
04c692a8 | 760 | (Not available on Win32) |
51a35ef1 | 761 | |
04c692a8 | 762 | =item * minitest |
51a35ef1 | 763 | |
04c692a8 DR |
764 | Run F<miniperl> on F<t/base>, F<t/comp>, F<t/cmd>, F<t/run>, F<t/io>, |
765 | F<t/op>, F<t/uni> and F<t/mro> tests. | |
51a35ef1 | 766 | |
04c692a8 | 767 | =item * test.valgrind check.valgrind utest.valgrind ucheck.valgrind |
51a35ef1 | 768 | |
04c692a8 DR |
769 | (Only in Linux) Run all the tests using the memory leak + naughty |
770 | memory access tool "valgrind". The log files will be named | |
771 | F<testname.valgrind>. | |
83f0ef60 | 772 | |
04c692a8 | 773 | =item * test.torture torturetest |
83f0ef60 | 774 | |
a8d15a22 | 775 | Run all the usual tests and some extra tests. As of Perl 5.8.0, the only |
04c692a8 | 776 | extra tests are Abigail's JAPHs, F<t/japh/abigail.t>. |
83f0ef60 | 777 | |
04c692a8 DR |
778 | You can also run the torture test with F<t/harness> by giving |
779 | C<-torture> argument to F<t/harness>. | |
83f0ef60 | 780 | |
04c692a8 | 781 | =item * utest ucheck test.utf8 check.utf8 |
83f0ef60 | 782 | |
04c692a8 | 783 | Run all the tests with -Mutf8. Not all tests will succeed. |
83f0ef60 | 784 | |
04c692a8 | 785 | (Not available on Win32) |
83f0ef60 | 786 | |
04c692a8 | 787 | =item * minitest.utf16 test.utf16 |
83f0ef60 | 788 | |
04c692a8 DR |
789 | Runs the tests with UTF-16 encoded scripts, encoded with different |
790 | versions of this encoding. | |
83f0ef60 | 791 | |
04c692a8 DR |
792 | C<make utest.utf16> runs the test suite with a combination of C<-utf8> |
793 | and C<-utf16> arguments to F<t/TEST>. | |
83f0ef60 | 794 | |
04c692a8 | 795 | (Not available on Win32) |
83f0ef60 | 796 | |
04c692a8 | 797 | =item * test_harness |
83f0ef60 | 798 | |
04c692a8 DR |
799 | Run the test suite with the F<t/harness> controlling program, instead |
800 | of F<t/TEST>. F<t/harness> is more sophisticated, and uses the | |
801 | L<Test::Harness> module, thus using this test target supposes that perl | |
802 | mostly works. The main advantage for our purposes is that it prints a | |
803 | detailed summary of failed tests at the end. Also, unlike F<t/TEST>, it | |
804 | doesn't redirect stderr to stdout. | |
83f0ef60 | 805 | |
04c692a8 DR |
806 | Note that under Win32 F<t/harness> is always used instead of F<t/TEST>, |
807 | so there is no special "test_harness" target. | |
83f0ef60 | 808 | |
04c692a8 DR |
809 | Under Win32's "test" target you may use the TEST_SWITCHES and |
810 | TEST_FILES environment variables to control the behaviour of | |
811 | F<t/harness>. This means you can say | |
83f0ef60 | 812 | |
04c692a8 DR |
813 | nmake test TEST_FILES="op/*.t" |
814 | nmake test TEST_SWITCHES="-torture" TEST_FILES="op/*.t" | |
83f0ef60 | 815 | |
78087e0a R |
816 | =item * test-notty test_notty |
817 | ||
818 | Sets PERL_SKIP_TTY_TEST to true before running normal test. | |
819 | ||
83f0ef60 JH |
820 | =back |
821 | ||
04c692a8 | 822 | =head2 Parallel tests |
83f0ef60 | 823 | |
04c692a8 DR |
824 | The core distribution can now run its regression tests in parallel on |
825 | Unix-like platforms. Instead of running C<make test>, set C<TEST_JOBS> | |
826 | in your environment to the number of tests to run in parallel, and run | |
827 | C<make test_harness>. On a Bourne-like shell, this can be done as | |
07aa3531 | 828 | |
04c692a8 | 829 | TEST_JOBS=3 make test_harness # Run 3 tests in parallel |
07aa3531 | 830 | |
04c692a8 DR |
831 | An environment variable is used, rather than parallel make itself, |
832 | because L<TAP::Harness> needs to be able to schedule individual | |
833 | non-conflicting test scripts itself, and there is no standard interface | |
834 | to C<make> utilities to interact with their job schedulers. | |
51a35ef1 | 835 | |
04c692a8 | 836 | Note that currently some test scripts may fail when run in parallel (most |
52b65e49 | 837 | notably F<ext/IO/t/io_dir.t>). If necessary, run just the failing scripts |
04c692a8 | 838 | again sequentially and see if the failures go away. |
51a35ef1 | 839 | |
04c692a8 | 840 | =head2 Running tests by hand |
51a35ef1 | 841 | |
a8d15a22 R |
842 | You can run part of the test suite by hand by using one of the following |
843 | commands from the F<t/> directory: | |
51a35ef1 | 844 | |
04c692a8 | 845 | ./perl -I../lib TEST list-of-.t-files |
51a35ef1 | 846 | |
04c692a8 | 847 | or |
51a35ef1 | 848 | |
04c692a8 | 849 | ./perl -I../lib harness list-of-.t-files |
51a35ef1 | 850 | |
a8d15a22 | 851 | (If you don't specify test scripts, the whole test suite will be run.) |
51a35ef1 | 852 | |
04c692a8 | 853 | =head2 Using F<t/harness> for testing |
51a35ef1 | 854 | |
a8d15a22 | 855 | If you use C<harness> for testing, you have several command line options |
04c692a8 DR |
856 | available to you. The arguments are as follows, and are in the order |
857 | that they must appear if used together. | |
51a35ef1 | 858 | |
04c692a8 DR |
859 | harness -v -torture -re=pattern LIST OF FILES TO TEST |
860 | harness -v -torture -re LIST OF PATTERNS TO MATCH | |
07aa3531 | 861 | |
a8d15a22 | 862 | If C<LIST OF FILES TO TEST> is omitted, the file list is obtained from |
04c692a8 DR |
863 | the manifest. The file list may include shell wildcards which will be |
864 | expanded out. | |
07aa3531 | 865 | |
04c692a8 | 866 | =over 4 |
4ae3d70a | 867 | |
04c692a8 | 868 | =item * -v |
4ae3d70a | 869 | |
04c692a8 DR |
870 | Run the tests under verbose mode so you can see what tests were run, |
871 | and debug output. | |
51a35ef1 | 872 | |
04c692a8 | 873 | =item * -torture |
4ae3d70a | 874 | |
04c692a8 | 875 | Run the torture tests as well as the normal set. |
4ae3d70a | 876 | |
04c692a8 | 877 | =item * -re=PATTERN |
6c41479b | 878 | |
04c692a8 DR |
879 | Filter the file list so that all the test files run match PATTERN. Note |
880 | that this form is distinct from the B<-re LIST OF PATTERNS> form below | |
881 | in that it allows the file list to be provided as well. | |
6c41479b | 882 | |
04c692a8 | 883 | =item * -re LIST OF PATTERNS |
6c41479b | 884 | |
04c692a8 DR |
885 | Filter the file list so that all the test files run match |
886 | /(LIST|OF|PATTERNS)/. Note that with this form the patterns are joined | |
887 | by '|' and you cannot supply a list of files, instead the test files | |
888 | are obtained from the MANIFEST. | |
6c41479b | 889 | |
04c692a8 | 890 | =back |
6c41479b | 891 | |
04c692a8 | 892 | You can run an individual test by a command similar to |
6c41479b | 893 | |
a8d15a22 | 894 | ./perl -I../lib path/to/foo.t |
6c41479b | 895 | |
04c692a8 DR |
896 | except that the harnesses set up some environment variables that may |
897 | affect the execution of the test: | |
6c41479b JH |
898 | |
899 | =over 4 | |
900 | ||
04c692a8 | 901 | =item * PERL_CORE=1 |
6c41479b | 902 | |
a8d15a22 | 903 | indicates that we're running this test as part of the perl core test |
04c692a8 | 904 | suite. This is useful for modules that have a dual life on CPAN. |
6c41479b | 905 | |
04c692a8 | 906 | =item * PERL_DESTRUCT_LEVEL=2 |
6c41479b | 907 | |
04c692a8 | 908 | is set to 2 if it isn't set already (see |
a8d15a22 | 909 | L<perlhacktips/PERL_DESTRUCT_LEVEL>). |
6c41479b | 910 | |
04c692a8 | 911 | =item * PERL |
6c41479b | 912 | |
04c692a8 DR |
913 | (used only by F<t/TEST>) if set, overrides the path to the perl |
914 | executable that should be used to run the tests (the default being | |
915 | F<./perl>). | |
6c41479b | 916 | |
04c692a8 | 917 | =item * PERL_SKIP_TTY_TEST |
6c41479b | 918 | |
04c692a8 DR |
919 | if set, tells to skip the tests that need a terminal. It's actually set |
920 | automatically by the Makefile, but can also be forced artificially by | |
921 | running 'make test_notty'. | |
6c41479b | 922 | |
04c692a8 | 923 | =back |
6c41479b | 924 | |
04c692a8 | 925 | =head3 Other environment variables that may influence tests |
6c41479b | 926 | |
04c692a8 | 927 | =over 4 |
6c41479b | 928 | |
04c692a8 | 929 | =item * PERL_TEST_Net_Ping |
6c41479b | 930 | |
04c692a8 DR |
931 | Setting this variable runs all the Net::Ping modules tests, otherwise |
932 | some tests that interact with the outside world are skipped. See | |
933 | L<perl58delta>. | |
6c41479b | 934 | |
04c692a8 | 935 | =item * PERL_TEST_NOVREXX |
cce04beb | 936 | |
04c692a8 | 937 | Setting this variable skips the vrexx.t tests for OS2::REXX. |
cce04beb | 938 | |
04c692a8 | 939 | =item * PERL_TEST_NUMCONVERTS |
cce04beb | 940 | |
04c692a8 | 941 | This sets a variable in op/numconvert.t. |
cce04beb | 942 | |
04c692a8 | 943 | =back |
cce04beb | 944 | |
04c692a8 DR |
945 | See also the documentation for the Test and Test::Harness modules, for |
946 | more environment variables that affect testing. | |
cce04beb | 947 | |
04c692a8 | 948 | =head1 MORE READING FOR GUTS HACKERS |
cce04beb | 949 | |
04c692a8 | 950 | To hack on the Perl guts, you'll need to read the following things: |
cce04beb | 951 | |
04c692a8 | 952 | =over 4 |
cce04beb | 953 | |
04c692a8 | 954 | =item * L<perlsource> |
b8ddf6b3 | 955 | |
04c692a8 DR |
956 | An overview of the Perl source tree. This will help you find the files |
957 | you're looking for. | |
b8ddf6b3 | 958 | |
04c692a8 | 959 | =item * L<perlinterp> |
b8ddf6b3 | 960 | |
04c692a8 DR |
961 | An overview of the Perl interpreter source code and some details on how |
962 | Perl does what it does. | |
b8ddf6b3 | 963 | |
04c692a8 | 964 | =item * L<perlhacktut> |
b8ddf6b3 | 965 | |
04c692a8 DR |
966 | This document walks through the creation of a small patch to Perl's C |
967 | code. If you're just getting started with Perl core hacking, this will | |
968 | help you understand how it works. | |
b8ddf6b3 | 969 | |
04c692a8 | 970 | =item * L<perlhacktips> |
b8ddf6b3 | 971 | |
04c692a8 DR |
972 | More details on hacking the Perl core. This document focuses on lower |
973 | level details such as how to write tests, compilation issues, | |
974 | portability, debugging, etc. | |
b8ddf6b3 | 975 | |
04c692a8 | 976 | If you plan on doing serious C hacking, make sure to read this. |
b8ddf6b3 | 977 | |
04c692a8 | 978 | =item * L<perlguts> |
b8ddf6b3 | 979 | |
04c692a8 DR |
980 | This is of paramount importance, since it's the documentation of what |
981 | goes where in the Perl source. Read it over a couple of times and it | |
982 | might start to make sense - don't worry if it doesn't yet, because the | |
983 | best way to study it is to read it in conjunction with poking at Perl | |
984 | source, and we'll do that later on. | |
b8ddf6b3 | 985 | |
04c692a8 DR |
986 | Gisle Aas's "illustrated perlguts", also known as I<illguts>, has very |
987 | helpful pictures: | |
9965345d | 988 | |
04c692a8 | 989 | L<http://search.cpan.org/dist/illguts/> |
9965345d | 990 | |
04c692a8 | 991 | =item * L<perlxstut> and L<perlxs> |
f1fac472 | 992 | |
04c692a8 DR |
993 | A working knowledge of XSUB programming is incredibly useful for core |
994 | hacking; XSUBs use techniques drawn from the PP code, the portion of | |
995 | the guts that actually executes a Perl program. It's a lot gentler to | |
996 | learn those techniques from simple examples and explanation than from | |
997 | the core itself. | |
f1fac472 | 998 | |
04c692a8 | 999 | =item * L<perlapi> |
f1fac472 | 1000 | |
04c692a8 DR |
1001 | The documentation for the Perl API explains what some of the internal |
1002 | functions do, as well as the many macros used in the source. | |
f1fac472 | 1003 | |
04c692a8 | 1004 | =item * F<Porting/pumpkin.pod> |
f1fac472 | 1005 | |
04c692a8 DR |
1006 | This is a collection of words of wisdom for a Perl porter; some of it |
1007 | is only useful to the pumpkin holder, but most of it applies to anyone | |
1008 | wanting to go about Perl development. | |
f1fac472 | 1009 | |
04c692a8 | 1010 | =item * The perl5-porters FAQ |
f1fac472 | 1011 | |
04c692a8 DR |
1012 | This should be available from |
1013 | http://dev.perl.org/perl5/docs/p5p-faq.html . It contains hints on | |
1014 | reading perl5-porters, information on how perl5-porters works and how | |
1015 | Perl development in general works. | |
f1fac472 | 1016 | |
04c692a8 | 1017 | =back |
f1fac472 | 1018 | |
04c692a8 | 1019 | =head1 CPAN TESTERS AND PERL SMOKERS |
f1fac472 | 1020 | |
04c692a8 DR |
1021 | The CPAN testers ( http://testers.cpan.org/ ) are a group of volunteers |
1022 | who test CPAN modules on a variety of platforms. | |
b8ddf6b3 | 1023 | |
a8d15a22 | 1024 | Perl Smokers ( http://www.nntp.perl.org/group/perl.daily-build/ and |
04c692a8 DR |
1025 | http://www.nntp.perl.org/group/perl.daily-build.reports/ ) |
1026 | automatically test Perl source releases on platforms with various | |
1027 | configurations. | |
f1fac472 | 1028 | |
04c692a8 DR |
1029 | Both efforts welcome volunteers. In order to get involved in smoke |
1030 | testing of the perl itself visit | |
a8d15a22 | 1031 | L<http://search.cpan.org/dist/Test-Smoke/>. In order to start smoke |
04c692a8 DR |
1032 | testing CPAN modules visit |
1033 | L<http://search.cpan.org/dist/CPANPLUS-YACSmoke/> or | |
1034 | L<http://search.cpan.org/dist/minismokebox/> or | |
1035 | L<http://search.cpan.org/dist/CPAN-Reporter/>. | |
f1fac472 | 1036 | |
04c692a8 | 1037 | =head1 WHAT NEXT? |
a422fd2d | 1038 | |
04c692a8 DR |
1039 | If you've read all the documentation in the document and the ones |
1040 | listed above, you're more than ready to hack on Perl. | |
a422fd2d | 1041 | |
04c692a8 | 1042 | Here's some more recommendations |
a422fd2d | 1043 | |
04c692a8 | 1044 | =over 4 |
a422fd2d SC |
1045 | |
1046 | =item * | |
1047 | ||
1048 | Subscribe to perl5-porters, follow the patches and try and understand | |
1049 | them; don't be afraid to ask if there's a portion you're not clear on - | |
1050 | who knows, you may unearth a bug in the patch... | |
1051 | ||
1052 | =item * | |
1053 | ||
04c692a8 DR |
1054 | Do read the README associated with your operating system, e.g. |
1055 | README.aix on the IBM AIX OS. Don't hesitate to supply patches to that | |
1056 | README if you find anything missing or changed over a new OS release. | |
a1f349fd MB |
1057 | |
1058 | =item * | |
1059 | ||
a422fd2d SC |
1060 | Find an area of Perl that seems interesting to you, and see if you can |
1061 | work out how it works. Scan through the source, and step over it in the | |
1062 | debugger. Play, poke, investigate, fiddle! You'll probably get to | |
04c692a8 DR |
1063 | understand not just your chosen area but a much wider range of |
1064 | F<perl>'s activity as well, and probably sooner than you'd think. | |
a422fd2d SC |
1065 | |
1066 | =back | |
1067 | ||
04c692a8 | 1068 | =head2 "The Road goes ever on and on, down from the door where it began." |
a422fd2d | 1069 | |
04c692a8 DR |
1070 | If you can do these things, you've started on the long road to Perl |
1071 | porting. Thanks for wanting to help make Perl better - and happy | |
1072 | hacking! | |
a422fd2d | 1073 | |
4ac71550 TC |
1074 | =head2 Metaphoric Quotations |
1075 | ||
1076 | If you recognized the quote about the Road above, you're in luck. | |
1077 | ||
04c692a8 DR |
1078 | Most software projects begin each file with a literal description of |
1079 | each file's purpose. Perl instead begins each with a literary allusion | |
1080 | to that file's purpose. | |
4ac71550 | 1081 | |
04c692a8 | 1082 | Like chapters in many books, all top-level Perl source files (along |
1cecf2c0 | 1083 | with a few others here and there) begin with an epigrammatic inscription |
04c692a8 DR |
1084 | that alludes, indirectly and metaphorically, to the material you're |
1085 | about to read. | |
4ac71550 | 1086 | |
a8d15a22 | 1087 | Quotations are taken from writings of J.R.R. Tolkien pertaining to his |
04c692a8 | 1088 | Legendarium, almost always from I<The Lord of the Rings>. Chapters and |
4ac71550 TC |
1089 | page numbers are given using the following editions: |
1090 | ||
1091 | =over 4 | |
1092 | ||
04c692a8 | 1093 | =item * |
4ac71550 | 1094 | |
04c692a8 DR |
1095 | I<The Hobbit>, by J.R.R. Tolkien. The hardcover, 70th-anniversary |
1096 | edition of 2007 was used, published in the UK by Harper Collins | |
1097 | Publishers and in the US by the Houghton Mifflin Company. | |
4ac71550 TC |
1098 | |
1099 | =item * | |
1100 | ||
04c692a8 DR |
1101 | I<The Lord of the Rings>, by J.R.R. Tolkien. The hardcover, |
1102 | 50th-anniversary edition of 2004 was used, published in the UK by | |
1103 | Harper Collins Publishers and in the US by the Houghton Mifflin | |
1104 | Company. | |
4ac71550 TC |
1105 | |
1106 | =item * | |
1107 | ||
04c692a8 DR |
1108 | I<The Lays of Beleriand>, by J.R.R. Tolkien and published posthumously |
1109 | by his son and literary executor, C.J.R. Tolkien, being the 3rd of the | |
1110 | 12 volumes in Christopher's mammoth I<History of Middle Earth>. Page | |
1111 | numbers derive from the hardcover edition, first published in 1983 by | |
1112 | George Allen & Unwin; no page numbers changed for the special 3-volume | |
1113 | omnibus edition of 2002 or the various trade-paper editions, all again | |
1114 | now by Harper Collins or Houghton Mifflin. | |
4ac71550 TC |
1115 | |
1116 | =back | |
1117 | ||
04c692a8 DR |
1118 | Other JRRT books fair game for quotes would thus include I<The |
1119 | Adventures of Tom Bombadil>, I<The Silmarillion>, I<Unfinished Tales>, | |
1120 | and I<The Tale of the Children of Hurin>, all but the first | |
1121 | posthumously assembled by CJRT. But I<The Lord of the Rings> itself is | |
1122 | perfectly fine and probably best to quote from, provided you can find a | |
1123 | suitable quote there. | |
4ac71550 | 1124 | |
04c692a8 DR |
1125 | So if you were to supply a new, complete, top-level source file to add |
1126 | to Perl, you should conform to this peculiar practice by yourself | |
1127 | selecting an appropriate quotation from Tolkien, retaining the original | |
1128 | spelling and punctuation and using the same format the rest of the | |
1129 | quotes are in. Indirect and oblique is just fine; remember, it's a | |
1130 | metaphor, so being meta is, after all, what it's for. | |
4ac71550 | 1131 | |
e8cd7eae GS |
1132 | =head1 AUTHOR |
1133 | ||
04c692a8 DR |
1134 | This document was originally written by Nathan Torkington, and is |
1135 | maintained by the perl5-porters mailing list. | |
b16c2e4a | 1136 |