| 1 | .\" Automatically generated by Pod::Man v1.34, Pod::Parser v1.13 |
| 2 | .\" |
| 3 | .\" Standard preamble: |
| 4 | .\" ======================================================================== |
| 5 | .de Sh \" Subsection heading |
| 6 | .br |
| 7 | .if t .Sp |
| 8 | .ne 5 |
| 9 | .PP |
| 10 | \fB\\$1\fR |
| 11 | .PP |
| 12 | .. |
| 13 | .de Sp \" Vertical space (when we can't use .PP) |
| 14 | .if t .sp .5v |
| 15 | .if n .sp |
| 16 | .. |
| 17 | .de Vb \" Begin verbatim text |
| 18 | .ft CW |
| 19 | .nf |
| 20 | .ne \\$1 |
| 21 | .. |
| 22 | .de Ve \" End verbatim text |
| 23 | .ft R |
| 24 | .fi |
| 25 | .. |
| 26 | .\" Set up some character translations and predefined strings. \*(-- will |
| 27 | .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left |
| 28 | .\" double quote, and \*(R" will give a right double quote. | will give a |
| 29 | .\" real vertical bar. \*(C+ will give a nicer C++. Capital omega is used to |
| 30 | .\" do unbreakable dashes and therefore won't be available. \*(C` and \*(C' |
| 31 | .\" expand to `' in nroff, nothing in troff, for use with C<>. |
| 32 | .tr \(*W-|\(bv\*(Tr |
| 33 | .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' |
| 34 | .ie n \{\ |
| 35 | . ds -- \(*W- |
| 36 | . ds PI pi |
| 37 | . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch |
| 38 | . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch |
| 39 | . ds L" "" |
| 40 | . ds R" "" |
| 41 | . ds C` "" |
| 42 | . ds C' "" |
| 43 | 'br\} |
| 44 | .el\{\ |
| 45 | . ds -- \|\(em\| |
| 46 | . ds PI \(*p |
| 47 | . ds L" `` |
| 48 | . ds R" '' |
| 49 | 'br\} |
| 50 | .\" |
| 51 | .\" If the F register is turned on, we'll generate index entries on stderr for |
| 52 | .\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index |
| 53 | .\" entries marked with X<> in POD. Of course, you'll have to process the |
| 54 | .\" output yourself in some meaningful fashion. |
| 55 | .if \nF \{\ |
| 56 | . de IX |
| 57 | . tm Index:\\$1\t\\n%\t"\\$2" |
| 58 | .. |
| 59 | . nr % 0 |
| 60 | . rr F |
| 61 | .\} |
| 62 | .\" |
| 63 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
| 64 | .\" way too many mistakes in technical documents. |
| 65 | .hy 0 |
| 66 | .if n .na |
| 67 | .\" |
| 68 | .\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2). |
| 69 | .\" Fear. Run. Save yourself. No user-serviceable parts. |
| 70 | . \" fudge factors for nroff and troff |
| 71 | .if n \{\ |
| 72 | . ds #H 0 |
| 73 | . ds #V .8m |
| 74 | . ds #F .3m |
| 75 | . ds #[ \f1 |
| 76 | . ds #] \fP |
| 77 | .\} |
| 78 | .if t \{\ |
| 79 | . ds #H ((1u-(\\\\n(.fu%2u))*.13m) |
| 80 | . ds #V .6m |
| 81 | . ds #F 0 |
| 82 | . ds #[ \& |
| 83 | . ds #] \& |
| 84 | .\} |
| 85 | . \" simple accents for nroff and troff |
| 86 | .if n \{\ |
| 87 | . ds ' \& |
| 88 | . ds ` \& |
| 89 | . ds ^ \& |
| 90 | . ds , \& |
| 91 | . ds ~ ~ |
| 92 | . ds / |
| 93 | .\} |
| 94 | .if t \{\ |
| 95 | . ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" |
| 96 | . ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' |
| 97 | . ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' |
| 98 | . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' |
| 99 | . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' |
| 100 | . ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' |
| 101 | .\} |
| 102 | . \" troff and (daisy-wheel) nroff accents |
| 103 | .ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V' |
| 104 | .ds 8 \h'\*(#H'\(*b\h'-\*(#H' |
| 105 | .ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#] |
| 106 | .ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H' |
| 107 | .ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u' |
| 108 | .ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#] |
| 109 | .ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#] |
| 110 | .ds ae a\h'-(\w'a'u*4/10)'e |
| 111 | .ds Ae A\h'-(\w'A'u*4/10)'E |
| 112 | . \" corrections for vroff |
| 113 | .if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u' |
| 114 | .if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u' |
| 115 | . \" for low resolution devices (crt and lpr) |
| 116 | .if \n(.H>23 .if \n(.V>19 \ |
| 117 | \{\ |
| 118 | . ds : e |
| 119 | . ds 8 ss |
| 120 | . ds o a |
| 121 | . ds d- d\h'-1'\(ga |
| 122 | . ds D- D\h'-1'\(hy |
| 123 | . ds th \o'bp' |
| 124 | . ds Th \o'LP' |
| 125 | . ds ae ae |
| 126 | . ds Ae AE |
| 127 | .\} |
| 128 | .rm #[ #] #H #V #F C |
| 129 | .\" ======================================================================== |
| 130 | .\" |
| 131 | .IX Title "PERLNEWMOD 1" |
| 132 | .TH PERLNEWMOD 1 "2002-06-08" "perl v5.8.0" "Perl Programmers Reference Guide" |
| 133 | .SH "NAME" |
| 134 | perlnewmod \- preparing a new module for distribution |
| 135 | .SH "DESCRIPTION" |
| 136 | .IX Header "DESCRIPTION" |
| 137 | This document gives you some suggestions about how to go about writing |
| 138 | Perl modules, preparing them for distribution, and making them available |
| 139 | via \s-1CPAN\s0. |
| 140 | .PP |
| 141 | One of the things that makes Perl really powerful is the fact that Perl |
| 142 | hackers tend to want to share the solutions to problems they've faced, |
| 143 | so you and I don't have to battle with the same problem again. |
| 144 | .PP |
| 145 | The main way they do this is by abstracting the solution into a Perl |
| 146 | module. If you don't know what one of these is, the rest of this |
| 147 | document isn't going to be much use to you. You're also missing out on |
| 148 | an awful lot of useful code; consider having a look at perlmod, |
| 149 | perlmodlib and perlmodinstall before coming back here. |
| 150 | .PP |
| 151 | When you've found that there isn't a module available for what you're |
| 152 | trying to do, and you've had to write the code yourself, consider |
| 153 | packaging up the solution into a module and uploading it to \s-1CPAN\s0 so that |
| 154 | others can benefit. |
| 155 | .Sh "Warning" |
| 156 | .IX Subsection "Warning" |
| 157 | We're going to primarily concentrate on Perl-only modules here, rather |
| 158 | than \s-1XS\s0 modules. \s-1XS\s0 modules serve a rather different purpose, and |
| 159 | you should consider different things before distributing them \- the |
| 160 | popularity of the library you are gluing, the portability to other |
| 161 | operating systems, and so on. However, the notes on preparing the Perl |
| 162 | side of the module and packaging and distributing it will apply equally |
| 163 | well to an \s-1XS\s0 module as a pure-Perl one. |
| 164 | .Sh "What should I make into a module?" |
| 165 | .IX Subsection "What should I make into a module?" |
| 166 | You should make a module out of any code that you think is going to be |
| 167 | useful to others. Anything that's likely to fill a hole in the communal |
| 168 | library and which someone else can slot directly into their program. Any |
| 169 | part of your code which you can isolate and extract and plug into |
| 170 | something else is a likely candidate. |
| 171 | .PP |
| 172 | Let's take an example. Suppose you're reading in data from a local |
| 173 | format into a hash-of-hashes in Perl, turning that into a tree, walking |
| 174 | the tree and then piping each node to an Acme Transmogrifier Server. |
| 175 | .PP |
| 176 | Now, quite a few people have the Acme Transmogrifier, and you've had to |
| 177 | write something to talk the protocol from scratch \- you'd almost |
| 178 | certainly want to make that into a module. The level at which you pitch |
| 179 | it is up to you: you might want protocol-level modules analogous to |
| 180 | Net::SMTP which then talk to higher level modules analogous |
| 181 | to Mail::Send. The choice is yours, but you do want to get |
| 182 | a module out for that server protocol. |
| 183 | .PP |
| 184 | Nobody else on the planet is going to talk your local data format, so we |
| 185 | can ignore that. But what about the thing in the middle? Building tree |
| 186 | structures from Perl variables and then traversing them is a nice, |
| 187 | general problem, and if nobody's already written a module that does |
| 188 | that, you might want to modularise that code too. |
| 189 | .PP |
| 190 | So hopefully you've now got a few ideas about what's good to modularise. |
| 191 | Let's now see how it's done. |
| 192 | .Sh "Step\-by\-step: Preparing the ground" |
| 193 | .IX Subsection "Step-by-step: Preparing the ground" |
| 194 | Before we even start scraping out the code, there are a few things we'll |
| 195 | want to do in advance. |
| 196 | .IP "Look around" 3 |
| 197 | .IX Item "Look around" |
| 198 | Dig into a bunch of modules to see how they're written. I'd suggest |
| 199 | starting with Text::Tabs, since it's in the standard |
| 200 | library and is nice and simple, and then looking at something like |
| 201 | Time::Zone, File::Copy and then some of the |
| 202 | \&\f(CW\*(C`Mail::*\*(C'\fR modules if you're planning on writing object oriented code. |
| 203 | .Sp |
| 204 | These should give you an overall feel for how modules are laid out and |
| 205 | written. |
| 206 | .IP "Check it's new" 3 |
| 207 | .IX Item "Check it's new" |
| 208 | There are a lot of modules on \s-1CPAN\s0, and it's easy to miss one that's |
| 209 | similar to what you're planning on contributing. Have a good plough |
| 210 | through the modules list and the \fIby-module\fR directories, and make sure |
| 211 | you're not the one reinventing the wheel! |
| 212 | .IP "Discuss the need" 3 |
| 213 | .IX Item "Discuss the need" |
| 214 | You might love it. You might feel that everyone else needs it. But there |
| 215 | might not actually be any real demand for it out there. If you're unsure |
| 216 | about the demand you're module will have, consider sending out feelers |
| 217 | on the \f(CW\*(C`comp.lang.perl.modules\*(C'\fR newsgroup, or as a last resort, ask the |
| 218 | modules list at \f(CW\*(C`modules@perl.org\*(C'\fR. Remember that this is a closed list |
| 219 | with a very long turn-around time \- be prepared to wait a good while for |
| 220 | a response from them. |
| 221 | .IP "Choose a name" 3 |
| 222 | .IX Item "Choose a name" |
| 223 | Perl modules included on \s-1CPAN\s0 have a naming hierarchy you should try to |
| 224 | fit in with. See perlmodlib for more details on how this works, and |
| 225 | browse around \s-1CPAN\s0 and the modules list to get a feel of it. At the very |
| 226 | least, remember this: modules should be title capitalised, (This::Thing) |
| 227 | fit in with a category, and explain their purpose succinctly. |
| 228 | .IP "Check again" 3 |
| 229 | .IX Item "Check again" |
| 230 | While you're doing that, make really sure you haven't missed a module |
| 231 | similar to the one you're about to write. |
| 232 | .Sp |
| 233 | When you've got your name sorted out and you're sure that your module is |
| 234 | wanted and not currently available, it's time to start coding. |
| 235 | .Sh "Step\-by\-step: Making the module" |
| 236 | .IX Subsection "Step-by-step: Making the module" |
| 237 | .IP "Start with \fIh2xs\fR" 3 |
| 238 | .IX Item "Start with h2xs" |
| 239 | Originally a utility to convert C header files into \s-1XS\s0 modules, |
| 240 | h2xs has become a useful utility for churning out skeletons for |
| 241 | Perl-only modules as well. If you don't want to use the |
| 242 | Autoloader which splits up big modules into smaller |
| 243 | subroutine-sized chunks, you'll say something like this: |
| 244 | .Sp |
| 245 | .Vb 1 |
| 246 | \& h2xs -AX -n Net::Acme |
| 247 | .Ve |
| 248 | .Sp |
| 249 | The \f(CW\*(C`\-A\*(C'\fR omits the Autoloader code, \f(CW\*(C`\-X\*(C'\fR omits \s-1XS\s0 elements, and \f(CW\*(C`\-n\*(C'\fR |
| 250 | specifies the name of the module. |
| 251 | .IP "Use strict and warnings" 3 |
| 252 | .IX Item "Use strict and warnings" |
| 253 | A module's code has to be warning and strict\-clean, since you can't |
| 254 | guarantee the conditions that it'll be used under. Besides, you wouldn't |
| 255 | want to distribute code that wasn't warning or strict-clean anyway, |
| 256 | right? |
| 257 | .IP "Use Carp" 3 |
| 258 | .IX Item "Use Carp" |
| 259 | The Carp module allows you to present your error messages from |
| 260 | the caller's perspective; this gives you a way to signal a problem with |
| 261 | the caller and not your module. For instance, if you say this: |
| 262 | .Sp |
| 263 | .Vb 1 |
| 264 | \& warn "No hostname given"; |
| 265 | .Ve |
| 266 | .Sp |
| 267 | the user will see something like this: |
| 268 | .Sp |
| 269 | .Vb 2 |
| 270 | \& No hostname given at /usr/local/lib/perl5/site_perl/5.6.0/Net/Acme.pm |
| 271 | \& line 123. |
| 272 | .Ve |
| 273 | .Sp |
| 274 | which looks like your module is doing something wrong. Instead, you want |
| 275 | to put the blame on the user, and say this: |
| 276 | .Sp |
| 277 | .Vb 1 |
| 278 | \& No hostname given at bad_code, line 10. |
| 279 | .Ve |
| 280 | .Sp |
| 281 | You do this by using Carp and replacing your \f(CW\*(C`warn\*(C'\fRs with |
| 282 | \&\f(CW\*(C`carp\*(C'\fRs. If you need to \f(CW\*(C`die\*(C'\fR, say \f(CW\*(C`croak\*(C'\fR instead. However, keep |
| 283 | \&\f(CW\*(C`warn\*(C'\fR and \f(CW\*(C`die\*(C'\fR in place for your sanity checks \- where it really is |
| 284 | your module at fault. |
| 285 | .IP "Use Exporter \- wisely!" 3 |
| 286 | .IX Item "Use Exporter - wisely!" |
| 287 | \&\f(CW\*(C`h2xs\*(C'\fR provides stubs for Exporter, which gives you a |
| 288 | standard way of exporting symbols and subroutines from your module into |
| 289 | the caller's namespace. For instance, saying \f(CW\*(C`use Net::Acme qw(&frob)\*(C'\fR |
| 290 | would import the \f(CW\*(C`frob\*(C'\fR subroutine. |
| 291 | .Sp |
| 292 | The package variable \f(CW@EXPORT\fR will determine which symbols will get |
| 293 | exported when the caller simply says \f(CW\*(C`use Net::Acme\*(C'\fR \- you will hardly |
| 294 | ever want to put anything in there. \f(CW@EXPORT_OK\fR, on the other hand, |
| 295 | specifies which symbols you're willing to export. If you do want to |
| 296 | export a bunch of symbols, use the \f(CW%EXPORT_TAGS\fR and define a standard |
| 297 | export set \- look at Exporter for more details. |
| 298 | .IP "Use plain old documentation" 3 |
| 299 | .IX Item "Use plain old documentation" |
| 300 | The work isn't over until the paperwork is done, and you're going to |
| 301 | need to put in some time writing some documentation for your module. |
| 302 | \&\f(CW\*(C`h2xs\*(C'\fR will provide a stub for you to fill in; if you're not sure about |
| 303 | the format, look at perlpod for an introduction. Provide a good |
| 304 | synopsis of how your module is used in code, a description, and then |
| 305 | notes on the syntax and function of the individual subroutines or |
| 306 | methods. Use Perl comments for developer notes and \s-1POD\s0 for end-user |
| 307 | notes. |
| 308 | .IP "Write tests" 3 |
| 309 | .IX Item "Write tests" |
| 310 | You're encouraged to create self-tests for your module to ensure it's |
| 311 | working as intended on the myriad platforms Perl supports; if you upload |
| 312 | your module to \s-1CPAN\s0, a host of testers will build your module and send |
| 313 | you the results of the tests. Again, \f(CW\*(C`h2xs\*(C'\fR provides a test framework |
| 314 | which you can extend \- you should do something more than just checking |
| 315 | your module will compile. |
| 316 | .IP "Write the \s-1README\s0" 3 |
| 317 | .IX Item "Write the README" |
| 318 | If you're uploading to \s-1CPAN\s0, the automated gremlins will extract the |
| 319 | \&\s-1README\s0 file and place that in your \s-1CPAN\s0 directory. It'll also appear in |
| 320 | the main \fIby-module\fR and \fIby-category\fR directories if you make it onto |
| 321 | the modules list. It's a good idea to put here what the module actually |
| 322 | does in detail, and the user-visible changes since the last release. |
| 323 | .Sh "Step\-by\-step: Distributing your module" |
| 324 | .IX Subsection "Step-by-step: Distributing your module" |
| 325 | .IP "Get a \s-1CPAN\s0 user \s-1ID\s0" 3 |
| 326 | .IX Item "Get a CPAN user ID" |
| 327 | Every developer publishing modules on \s-1CPAN\s0 needs a \s-1CPAN\s0 \s-1ID\s0. See the |
| 328 | instructions at \f(CW\*(C`http://www.cpan.org/modules/04pause.html\*(C'\fR (or |
| 329 | equivalent on your nearest mirror) to find out how to do this. |
| 330 | .ie n .IP """perl Makefile.PL; make test; make dist""" 3 |
| 331 | .el .IP "\f(CWperl Makefile.PL; make test; make dist\fR" 3 |
| 332 | .IX Item "perl Makefile.PL; make test; make dist" |
| 333 | Once again, \f(CW\*(C`h2xs\*(C'\fR has done all the work for you. It produces the |
| 334 | standard \f(CW\*(C`Makefile.PL\*(C'\fR you'll have seen when you downloaded and |
| 335 | installs modules, and this produces a Makefile with a \f(CW\*(C`dist\*(C'\fR target. |
| 336 | .Sp |
| 337 | Once you've ensured that your module passes its own tests \- always a |
| 338 | good thing to make sure \- you can \f(CW\*(C`make dist\*(C'\fR, and the Makefile will |
| 339 | hopefully produce you a nice tarball of your module, ready for upload. |
| 340 | .IP "Upload the tarball" 3 |
| 341 | .IX Item "Upload the tarball" |
| 342 | The email you got when you received your \s-1CPAN\s0 \s-1ID\s0 will tell you how to |
| 343 | log in to \s-1PAUSE\s0, the Perl Authors Upload SErver. From the menus there, |
| 344 | you can upload your module to \s-1CPAN\s0. |
| 345 | .IP "Announce to the modules list" 3 |
| 346 | .IX Item "Announce to the modules list" |
| 347 | Once uploaded, it'll sit unnoticed in your author directory. If you want |
| 348 | it connected to the rest of the \s-1CPAN\s0, you'll need to tell the modules |
| 349 | list about it. The best way to do this is to email them a line in the |
| 350 | style of the modules list, like this: |
| 351 | .Sp |
| 352 | .Vb 15 |
| 353 | \& Net::Acme bdpOP Interface to Acme Frobnicator servers FOOBAR |
| 354 | \& ^ ^^^^^ ^ ^ |
| 355 | \& | ||||| Module description Your ID |
| 356 | \& | ||||| |
| 357 | \& | ||||\e-Public Licence: (p)standard Perl, (g)GPL, (b)BSD, |
| 358 | \& | |||| (l)LGPL, (a)rtistic, (o)ther |
| 359 | \& | |||| |
| 360 | \& | |||\e- Interface: (O)OP, (r)eferences, (h)ybrid, (f)unctions |
| 361 | \& | ||| |
| 362 | \& | ||\e-- Language: (p)ure Perl, C(+)+, (h)ybrid, (C), (o)ther |
| 363 | \& | || |
| 364 | \& Module |\e--- Support: (d)eveloper, (m)ailing list, (u)senet, (n)one |
| 365 | \& Name | |
| 366 | \& \e---- Development: (i)dea, (c)onstructions, (a)lpha, (b)eta, |
| 367 | \& (R)eleased, (M)ature, (S)tandard |
| 368 | .Ve |
| 369 | .Sp |
| 370 | plus a description of the module and why you think it should be |
| 371 | included. If you hear nothing back, that means your module will |
| 372 | probably appear on the modules list at the next update. Don't try |
| 373 | subscribing to \f(CW\*(C`modules@perl.org\*(C'\fR; it's not another mailing list. Just |
| 374 | have patience. |
| 375 | .IP "Announce to clpa" 3 |
| 376 | .IX Item "Announce to clpa" |
| 377 | If you have a burning desire to tell the world about your release, post |
| 378 | an announcement to the moderated \f(CW\*(C`comp.lang.perl.announce\*(C'\fR newsgroup. |
| 379 | .IP "Fix bugs!" 3 |
| 380 | .IX Item "Fix bugs!" |
| 381 | Once you start accumulating users, they'll send you bug reports. If |
| 382 | you're lucky, they'll even send you patches. Welcome to the joys of |
| 383 | maintaining a software project... |
| 384 | .SH "AUTHOR" |
| 385 | .IX Header "AUTHOR" |
| 386 | Simon Cozens, \f(CW\*(C`simon@cpan.org\*(C'\fR |
| 387 | .SH "SEE ALSO" |
| 388 | .IX Header "SEE ALSO" |
| 389 | perlmod, perlmodlib, perlmodinstall, h2xs, strict, |
| 390 | Carp, Exporter, perlpod, Test, ExtUtils::MakeMaker, |
| 391 | http://www.cpan.org/ , Ken Williams' tutorial on building your own |
| 392 | module at http://mathforum.org/~ken/perl_modules.html |