| 1 | =head1 NAME |
| 2 | |
| 3 | perltodo - Perl TO-DO List |
| 4 | |
| 5 | =head1 DESCRIPTION |
| 6 | |
| 7 | This is a list of wishes for Perl. The tasks we think are smaller or easier |
| 8 | are listed first. Anyone is welcome to work on any of these, but it's a good |
| 9 | idea to first contact I<perl5-porters@perl.org> to avoid duplication of |
| 10 | effort. By all means contact a pumpking privately first if you prefer. |
| 11 | |
| 12 | Whilst patches to make the list shorter are most welcome, ideas to add to |
| 13 | the list are also encouraged. Check the perl5-porters archives for past |
| 14 | ideas, and any discussion about them. One set of archives may be found at: |
| 15 | |
| 16 | http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/ |
| 17 | |
| 18 | What can we offer you in return? Fame, fortune, and everlasting glory? Maybe |
| 19 | not, but if your patch is incorporated, then we'll add your name to the |
| 20 | F<AUTHORS> file, which ships in the official distribution. How many other |
| 21 | programming languages offer you 1 line of immortality? |
| 22 | |
| 23 | =head1 The roadmap to 5.10 |
| 24 | |
| 25 | The roadmap to 5.10 envisages feature based releases, as various items in this |
| 26 | TODO are completed. |
| 27 | |
| 28 | =head2 Needed for a 5.9.4 release |
| 29 | |
| 30 | =over |
| 31 | |
| 32 | =item * |
| 33 | |
| 34 | Review assertions. Review syntax to combine assertions. Assertions could take |
| 35 | advantage of the lexical pragmas work. L</What hooks would assertions need?> |
| 36 | |
| 37 | =back |
| 38 | |
| 39 | =head2 Needed for a 5.9.5 release |
| 40 | |
| 41 | =over |
| 42 | |
| 43 | =item * |
| 44 | Implement L</_ prototype character> |
| 45 | |
| 46 | =item * |
| 47 | Implement L</state variables> |
| 48 | |
| 49 | =back |
| 50 | |
| 51 | =head2 Needed for a 5.9.6 release |
| 52 | |
| 53 | Stabilisation. If all goes well, this will be the equivalent of a 5.10-beta. |
| 54 | |
| 55 | =head1 Tasks that only need Perl knowledge |
| 56 | |
| 57 | =head2 common test code for timed bail out |
| 58 | |
| 59 | Write portable self destruct code for tests to stop them burning CPU in |
| 60 | infinite loops. This needs to avoid using alarm, as some of the tests are |
| 61 | testing alarm/sleep or timers. |
| 62 | |
| 63 | =head2 POD -> HTML conversion in the core still sucks |
| 64 | |
| 65 | Which is crazy given just how simple POD purports to be, and how simple HTML |
| 66 | can be. It's not actually I<as> simple as it sounds, particularly with the |
| 67 | flexibility POD allows for C<=item>, but it would be good to improve the |
| 68 | visual appeal of the HTML generated, and to avoid it having any validation |
| 69 | errors. See also L</make HTML install work>, as the layout of installation tree |
| 70 | is needed to improve the cross-linking. |
| 71 | |
| 72 | The addition of C<Pod::Simple> and its related modules may make this task |
| 73 | easier to complete. |
| 74 | |
| 75 | =head2 Parallel testing |
| 76 | |
| 77 | The core regression test suite is getting ever more comprehensive, which has |
| 78 | the side effect that it takes longer to run. This isn't so good. Investigate |
| 79 | whether it would be feasible to give the harness script the B<option> of |
| 80 | running sets of tests in parallel. This would be useful for tests in |
| 81 | F<t/op/*.t> and F<t/uni/*.t> and maybe some sets of tests in F<lib/>. |
| 82 | |
| 83 | Questions to answer |
| 84 | |
| 85 | =over 4 |
| 86 | |
| 87 | =item 1 |
| 88 | |
| 89 | How does screen layout work when you're running more than one test? |
| 90 | |
| 91 | =item 2 |
| 92 | |
| 93 | How does the caller of test specify how many tests to run in parallel? |
| 94 | |
| 95 | =item 3 |
| 96 | |
| 97 | How do setup/teardown tests identify themselves? |
| 98 | |
| 99 | =back |
| 100 | |
| 101 | Pugs already does parallel testing - can their approach be re-used? |
| 102 | |
| 103 | =head2 Make Schwern poorer |
| 104 | |
| 105 | We should have for everything. When all the core's modules are tested, |
| 106 | Schwern has promised to donate to $500 to TPF. We may need volunteers to |
| 107 | hold him upside down and shake vigorously in order to actually extract the |
| 108 | cash. |
| 109 | |
| 110 | See F<t/lib/1_compile.t> for the 3 remaining modules that need tests. |
| 111 | |
| 112 | =head2 Improve the coverage of the core tests |
| 113 | |
| 114 | Use Devel::Cover to ascertain the core's test coverage, then add tests that |
| 115 | are currently missing. |
| 116 | |
| 117 | =head2 test B |
| 118 | |
| 119 | A full test suite for the B module would be nice. |
| 120 | |
| 121 | =head2 A decent benchmark |
| 122 | |
| 123 | C<perlbench> seems impervious to any recent changes made to the perl core. It |
| 124 | would be useful to have a reasonable general benchmarking suite that roughly |
| 125 | represented what current perl programs do, and measurably reported whether |
| 126 | tweaks to the core improve, degrade or don't really affect performance, to |
| 127 | guide people attempting to optimise the guts of perl. Gisle would welcome |
| 128 | new tests for perlbench. |
| 129 | |
| 130 | =head2 fix tainting bugs |
| 131 | |
| 132 | Fix the bugs revealed by running the test suite with the C<-t> switch (via |
| 133 | C<make test.taintwarn>). |
| 134 | |
| 135 | =head2 Dual life everything |
| 136 | |
| 137 | As part of the "dists" plan, anything that doesn't belong in the smallest perl |
| 138 | distribution needs to be dual lifed. Anything else can be too. Figure out what |
| 139 | changes would be needed to package that module and its tests up for CPAN, and |
| 140 | do so. Test it with older perl releases, and fix the problems you find. |
| 141 | |
| 142 | =head2 Improving C<threads::shared> |
| 143 | |
| 144 | Investigate whether C<threads::shared> could share aggregates properly with |
| 145 | only Perl level changes to shared.pm |
| 146 | |
| 147 | =head2 POSIX memory footprint |
| 148 | |
| 149 | Ilya observed that use POSIX; eats memory like there's no tomorrow, and at |
| 150 | various times worked to cut it down. There is probably still fat to cut out - |
| 151 | for example POSIX passes Exporter some very memory hungry data structures. |
| 152 | |
| 153 | |
| 154 | |
| 155 | |
| 156 | |
| 157 | |
| 158 | |
| 159 | =head1 Tasks that need a little sysadmin-type knowledge |
| 160 | |
| 161 | Or if you prefer, tasks that you would learn from, and broaden your skills |
| 162 | base... |
| 163 | |
| 164 | =head2 Relocatable perl |
| 165 | |
| 166 | The C level patches needed to create a relocatable perl binary are done, as |
| 167 | is the work on F<Config.pm>. All that's left to do is the C<Configure> tweaking |
| 168 | to let people specify how they want to do the install. |
| 169 | |
| 170 | =head2 make HTML install work |
| 171 | |
| 172 | There is an C<installhtml> target in the Makefile. It's marked as |
| 173 | "experimental". It would be good to get this tested, make it work reliably, and |
| 174 | remove the "experimental" tag. This would include |
| 175 | |
| 176 | =over 4 |
| 177 | |
| 178 | =item 1 |
| 179 | |
| 180 | Checking that cross linking between various parts of the documentation works. |
| 181 | In particular that links work between the modules (files with POD in F<lib/>) |
| 182 | and the core documentation (files in F<pod/>) |
| 183 | |
| 184 | =item 2 |
| 185 | |
| 186 | Work out how to split C<perlfunc> into chunks, preferably one per function |
| 187 | group, preferably with general case code that could be used elsewhere. |
| 188 | Challenges here are correctly identifying the groups of functions that go |
| 189 | together, and making the right named external cross-links point to the right |
| 190 | page. Things to be aware of are C<-X>, groups such as C<getpwnam> to |
| 191 | C<endservent>, two or more C<=items> giving the different parameter lists, such |
| 192 | as |
| 193 | |
| 194 | =item substr EXPR,OFFSET,LENGTH,REPLACEMENT |
| 195 | |
| 196 | =item substr EXPR,OFFSET,LENGTH |
| 197 | |
| 198 | =item substr EXPR,OFFSET |
| 199 | |
| 200 | and different parameter lists having different meanings. (eg C<select>) |
| 201 | |
| 202 | =back |
| 203 | |
| 204 | =head2 compressed man pages |
| 205 | |
| 206 | Be able to install them. This would probably need a configure test to see how |
| 207 | the system does compressed man pages (same directory/different directory? |
| 208 | same filename/different filename), as well as tweaking the F<installman> script |
| 209 | to compress as necessary. |
| 210 | |
| 211 | =head2 Add a code coverage target to the Makefile |
| 212 | |
| 213 | Make it easy for anyone to run Devel::Cover on the core's tests. The steps |
| 214 | to do this manually are roughly |
| 215 | |
| 216 | =over 4 |
| 217 | |
| 218 | =item * |
| 219 | |
| 220 | do a normal C<Configure>, but include Devel::Cover as a module to install |
| 221 | (see F<INSTALL> for how to do this) |
| 222 | |
| 223 | =item * |
| 224 | |
| 225 | make perl |
| 226 | |
| 227 | =item * |
| 228 | |
| 229 | cd t; HARNESS_PERL_SWITCHES=-MDevel::Cover ./perl -I../lib harness |
| 230 | |
| 231 | =item * |
| 232 | |
| 233 | Process the resulting Devel::Cover database |
| 234 | |
| 235 | =back |
| 236 | |
| 237 | This just give you the coverage of the F<.pm>s. To also get the C level |
| 238 | coverage you need to |
| 239 | |
| 240 | =over 4 |
| 241 | |
| 242 | =item * |
| 243 | |
| 244 | Additionally tell C<Configure> to use the appropriate C compiler flags for |
| 245 | C<gcov> |
| 246 | |
| 247 | =item * |
| 248 | |
| 249 | make perl.gcov |
| 250 | |
| 251 | (instead of C<make perl>) |
| 252 | |
| 253 | =item * |
| 254 | |
| 255 | After running the tests run C<gcov> to generate all the F<.gcov> files. |
| 256 | (Including down in the subdirectories of F<ext/> |
| 257 | |
| 258 | =item * |
| 259 | |
| 260 | (From the top level perl directory) run C<gcov2perl> on all the C<.gcov> files |
| 261 | to get their stats into the cover_db directory. |
| 262 | |
| 263 | =item * |
| 264 | |
| 265 | Then process the Devel::Cover database |
| 266 | |
| 267 | =back |
| 268 | |
| 269 | It would be good to add a single switch to C<Configure> to specify that you |
| 270 | wanted to perform perl level coverage, and another to specify C level |
| 271 | coverage, and have C<Configure> and the F<Makefile> do all the right things |
| 272 | automatically. |
| 273 | |
| 274 | =head2 Make Config.pm cope with differences between build and installed perl |
| 275 | |
| 276 | Quite often vendors ship a perl binary compiled with their (pay-for) |
| 277 | compilers. People install a free compiler, such as gcc. To work out how to |
| 278 | build extensions, Perl interrogates C<%Config>, so in this situation |
| 279 | C<%Config> describes compilers that aren't there, and extension building |
| 280 | fails. This forces people into choosing between re-compiling perl themselves |
| 281 | using the compiler they have, or only using modules that the vendor ships. |
| 282 | |
| 283 | It would be good to find a way teach C<Config.pm> about the installation setup, |
| 284 | possibly involving probing at install time or later, so that the C<%Config> in |
| 285 | a binary distribution better describes the installed machine, when the |
| 286 | installed machine differs from the build machine in some significant way. |
| 287 | |
| 288 | =head2 make parallel builds work |
| 289 | |
| 290 | Currently parallel builds (such as C<make -j3>) don't work reliably. We believe |
| 291 | that this is due to incomplete dependency specification in the F<Makefile>. |
| 292 | It would be good if someone were able to track down the causes of these |
| 293 | problems, so that parallel builds worked properly. |
| 294 | |
| 295 | =head2 linker specification files |
| 296 | |
| 297 | Some platforms mandate that you provide a list of a shared library's external |
| 298 | symbols to the linker, so the core already has the infrastructure in place to |
| 299 | do this for generating shared perl libraries. My understanding is that the |
| 300 | GNU toolchain can accept an optional linker specification file, and restrict |
| 301 | visibility just to symbols declared in that file. It would be good to extend |
| 302 | F<makedef.pl> to support this format, and to provide a means within |
| 303 | C<Configure> to enable it. This would allow Unix users to test that the |
| 304 | export list is correct, and to build a perl that does not pollute the global |
| 305 | namespace with private symbols. |
| 306 | |
| 307 | |
| 308 | |
| 309 | |
| 310 | =head1 Tasks that need a little C knowledge |
| 311 | |
| 312 | These tasks would need a little C knowledge, but don't need any specific |
| 313 | background or experience with XS, or how the Perl interpreter works |
| 314 | |
| 315 | =head2 Make it clear from -v if this is the exact official release |
| 316 | |
| 317 | Currently perl from C<p4>/C<rsync> ships with a F<patchlevel.h> file that |
| 318 | usually defines one local patch, of the form "MAINT12345" or "RC1". The output |
| 319 | of perl -v doesn't report that a perl isn't an official release, and this |
| 320 | information can get lost in bugs reports. Because of this, the minor version |
| 321 | isn't bumped up until RC time, to minimise the possibility of versions of perl |
| 322 | escaping that believe themselves to be newer than they actually are. |
| 323 | |
| 324 | It would be useful to find an elegant way to have the "this is an interim |
| 325 | maintenance release" or "this is a release candidate" in the terse -v output, |
| 326 | and have it so that it's easy for the pumpking to remove this just as the |
| 327 | release tarball is rolled up. This way the version pulled out of rsync would |
| 328 | always say "I'm a development release" and it would be safe to bump the |
| 329 | reported minor version as soon as a release ships, which would aid perl |
| 330 | developers. |
| 331 | |
| 332 | This task is really about thinking of an elegant way to arrange the C source |
| 333 | such that it's trivial for the Pumpking to flag "this is an official release" |
| 334 | when making a tarball, yet leave the default source saying "I'm not the |
| 335 | official release". |
| 336 | |
| 337 | =head2 Tidy up global variables |
| 338 | |
| 339 | There's a note in F<intrpvar.h> |
| 340 | |
| 341 | /* These two variables are needed to preserve 5.8.x bincompat because |
| 342 | we can't change function prototypes of two exported functions. |
| 343 | Probably should be taken out of blead soon, and relevant prototypes |
| 344 | changed. */ |
| 345 | |
| 346 | So doing this, and removing any of the unused variables still present would |
| 347 | be good. |
| 348 | |
| 349 | =head2 Ordering of "global" variables. |
| 350 | |
| 351 | F<thrdvar.h> and F<intrpvarh> define the "global" variables that need to be |
| 352 | per-thread under ithreads, where the variables are actually elements in a |
| 353 | structure. As C dictates, the variables must be laid out in order of |
| 354 | declaration. There is a comment |
| 355 | C</* Important ones in the first cache line (if alignment is done right) */> |
| 356 | which implies that at some point in the past the ordering was carefully chosen |
| 357 | (at least in part). However, it's clear that the ordering is less than perfect, |
| 358 | as currently there are things such as 7 C<bool>s in a row, then something |
| 359 | typically requiring 4 byte alignment, and then an odd C<bool> later on. |
| 360 | (C<bool>s are typically defined as C<char>s). So it would be good for someone |
| 361 | to review the ordering of the variables, to see how much alignment padding can |
| 362 | be removed. |
| 363 | |
| 364 | =head2 bincompat functions |
| 365 | |
| 366 | There are lots of functions which are retained for binary compatibility. |
| 367 | Clean these up. Move them to mathom.c, and don't compile for blead? |
| 368 | |
| 369 | =head2 am I hot or not? |
| 370 | |
| 371 | The idea of F<pp_hot.c> is that it contains the I<hot> ops, the ops that are |
| 372 | most commonly used. The idea is that by grouping them, their object code will |
| 373 | be adjacent in the executable, so they have a greater chance of already being |
| 374 | in the CPU cache (or swapped in) due to being near another op already in use. |
| 375 | |
| 376 | Except that it's not clear if these really are the most commonly used ops. So |
| 377 | anyone feeling like exercising their skill with coverage and profiling tools |
| 378 | might want to determine what ops I<really> are the most commonly used. And in |
| 379 | turn suggest evictions and promotions to achieve a better F<pp_hot.c>. |
| 380 | |
| 381 | =head2 emulate the per-thread memory pool on Unix |
| 382 | |
| 383 | For Windows, ithreads allocates memory for each thread from a separate pool, |
| 384 | which it discards at thread exit. It also checks that memory is free()d to |
| 385 | the correct pool. Neither check is done on Unix, so code developed there won't |
| 386 | be subject to such strictures, so can harbour bugs that only show up when the |
| 387 | code reaches Windows. |
| 388 | |
| 389 | It would be good to be able to optionally emulate the Window pool system on |
| 390 | Unix, to let developers who only have access to Unix, or want to use |
| 391 | Unix-specific debugging tools, check for these problems. To do this would |
| 392 | involve figuring out how the C<PerlMem_*> macros wrap C<malloc()> access, and |
| 393 | providing a layer that records/checks the identity of the thread making the |
| 394 | call, and recording all the memory allocated by each thread via this API so |
| 395 | that it can be summarily free()d at thread exit. One implementation idea |
| 396 | would be to increase the size of allocation, and store the C<my_perl> pointer |
| 397 | (to identify the thread) at the start, along with pointers to make a linked |
| 398 | list of blocks for this thread. To avoid alignment problems it would be |
| 399 | necessary to do something like |
| 400 | |
| 401 | union memory_header_padded { |
| 402 | struct memory_header { |
| 403 | void *thread_id; /* For my_perl */ |
| 404 | void *next; /* Pointer to next block for this thread */ |
| 405 | } data; |
| 406 | long double padding; /* whatever type has maximal alignment constraint */ |
| 407 | }; |
| 408 | |
| 409 | |
| 410 | although C<long double> might not be the only type to add to the padding |
| 411 | union. |
| 412 | |
| 413 | =head2 reduce duplication in sv_setsv_flags |
| 414 | |
| 415 | C<Perl_sv_setsv_flags> has a comment |
| 416 | C</* There's a lot of redundancy below but we're going for speed here */> |
| 417 | |
| 418 | Whilst this was true 10 years ago, the growing disparity between RAM and CPU |
| 419 | speeds mean that the trade offs have changed. In addition, the duplicate code |
| 420 | adds to the maintenance burden. It would be good to see how much of the |
| 421 | redundancy can be pruned, particular in the less common paths. (Profiling |
| 422 | tools at the ready...). For example, why does the test for |
| 423 | "Can't redefine active sort subroutine" need to occur in two places? |
| 424 | |
| 425 | |
| 426 | |
| 427 | |
| 428 | =head1 Tasks that need a knowledge of XS |
| 429 | |
| 430 | These tasks would need C knowledge, and roughly the level of knowledge of |
| 431 | the perl API that comes from writing modules that use XS to interface to |
| 432 | C. |
| 433 | |
| 434 | =head2 IPv6 |
| 435 | |
| 436 | Clean this up. Check everything in core works |
| 437 | |
| 438 | =head2 shrink C<GV>s, C<CV>s |
| 439 | |
| 440 | By removing unused elements and careful re-ordering, the structures for C<AV>s |
| 441 | and C<HV>s have recently been shrunk considerably. It's probable that the same |
| 442 | approach would find savings in C<GV>s and C<CV>s, if not all the other |
| 443 | larger-than-C<PVMG> types. |
| 444 | |
| 445 | =head2 merge Perl_sv_2[inpu]v |
| 446 | |
| 447 | There's a lot of code shared between C<Perl_sv_2iv_flags>, |
| 448 | C<Perl_sv_2uv_flags>, C<Perl_sv_2nv>, and C<Perl_sv_2pv_flags>. It would be |
| 449 | interesting to see if some of it can be merged into common shared static |
| 450 | functions. In particular, C<Perl_sv_2uv_flags> started out as a cut&paste |
| 451 | from C<Perl_sv_2iv_flags> around 5.005_50 time, and it may be possible to |
| 452 | replace both with a single function that returns a value or union which is |
| 453 | split out by the macros in F<sv.h> |
| 454 | |
| 455 | =head2 UTF8 caching code |
| 456 | |
| 457 | The string position/offset cache is not optional. It should be. |
| 458 | |
| 459 | =head2 Implicit Latin 1 => Unicode translation |
| 460 | |
| 461 | Conversions from byte strings to UTF-8 currently map high bit characters |
| 462 | to Unicode without translation (or, depending on how you look at it, by |
| 463 | implicitly assuming that the byte strings are in Latin-1). As perl assumes |
| 464 | the C locale by default, upgrading a string to UTF-8 may change the |
| 465 | meaning of its contents regarding character classes, case mapping, etc. |
| 466 | This should probably emit a warning (at least). |
| 467 | |
| 468 | This task is incremental - even a little bit of work on it will help. |
| 469 | |
| 470 | =head2 autovivification |
| 471 | |
| 472 | Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no strict; |
| 473 | |
| 474 | This task is incremental - even a little bit of work on it will help. |
| 475 | |
| 476 | =head2 Unicode in Filenames |
| 477 | |
| 478 | chdir, chmod, chown, chroot, exec, glob, link, lstat, mkdir, open, |
| 479 | opendir, qx, readdir, readlink, rename, rmdir, stat, symlink, sysopen, |
| 480 | system, truncate, unlink, utime, -X. All these could potentially accept |
| 481 | Unicode filenames either as input or output (and in the case of system |
| 482 | and qx Unicode in general, as input or output to/from the shell). |
| 483 | Whether a filesystem - an operating system pair understands Unicode in |
| 484 | filenames varies. |
| 485 | |
| 486 | Known combinations that have some level of understanding include |
| 487 | Microsoft NTFS, Apple HFS+ (In Mac OS 9 and X) and Apple UFS (in Mac |
| 488 | OS X), NFS v4 is rumored to be Unicode, and of course Plan 9. How to |
| 489 | create Unicode filenames, what forms of Unicode are accepted and used |
| 490 | (UCS-2, UTF-16, UTF-8), what (if any) is the normalization form used, |
| 491 | and so on, varies. Finding the right level of interfacing to Perl |
| 492 | requires some thought. Remember that an OS does not implicate a |
| 493 | filesystem. |
| 494 | |
| 495 | (The Windows -C command flag "wide API support" has been at least |
| 496 | temporarily retired in 5.8.1, and the -C has been repurposed, see |
| 497 | L<perlrun>.) |
| 498 | |
| 499 | =head2 Unicode in %ENV |
| 500 | |
| 501 | Currently the %ENV entries are always byte strings. |
| 502 | |
| 503 | =head2 use less 'memory' |
| 504 | |
| 505 | Investigate trade offs to switch out perl's choices on memory usage. |
| 506 | Particularly perl should be able to give memory back. |
| 507 | |
| 508 | This task is incremental - even a little bit of work on it will help. |
| 509 | |
| 510 | =head2 Re-implement C<:unique> in a way that is actually thread-safe |
| 511 | |
| 512 | The old implementation made bad assumptions on several levels. A good 90% |
| 513 | solution might be just to make C<:unique> work to share the string buffer |
| 514 | of SvPVs. That way large constant strings can be shared between ithreads, |
| 515 | such as the configuration information in F<Config>. |
| 516 | |
| 517 | =head2 Make tainting consistent |
| 518 | |
| 519 | Tainting would be easier to use if it didn't take documented shortcuts and |
| 520 | allow taint to "leak" everywhere within an expression. |
| 521 | |
| 522 | =head2 readpipe(LIST) |
| 523 | |
| 524 | system() accepts a LIST syntax (and a PROGRAM LIST syntax) to avoid |
| 525 | running a shell. readpipe() (the function behind qx//) could be similarly |
| 526 | extended. |
| 527 | |
| 528 | |
| 529 | |
| 530 | |
| 531 | |
| 532 | =head1 Tasks that need a knowledge of the interpreter |
| 533 | |
| 534 | These tasks would need C knowledge, and knowledge of how the interpreter works, |
| 535 | or a willingness to learn. |
| 536 | |
| 537 | =head2 lexical pragmas |
| 538 | |
| 539 | Document the new support for lexical pragmas in 5.9.3 and how %^H works. |
| 540 | Maybe C<re>, C<encoding>, maybe other pragmas could be made lexical. |
| 541 | |
| 542 | =head2 Attach/detach debugger from running program |
| 543 | |
| 544 | The old perltodo notes "With C<gdb>, you can attach the debugger to a running |
| 545 | program if you pass the process ID. It would be good to do this with the Perl |
| 546 | debugger on a running Perl program, although I'm not sure how it would be |
| 547 | done." ssh and screen do this with named pipes in /tmp. Maybe we can too. |
| 548 | |
| 549 | =head2 Constant folding |
| 550 | |
| 551 | The peephole optimiser should trap errors during constant folding, and give |
| 552 | up on the folding, rather than bailing out at compile time. It is quite |
| 553 | possible that the unfoldable constant is in unreachable code, eg something |
| 554 | akin to C<$a = 0/0 if 0;> |
| 555 | |
| 556 | =head2 LVALUE functions for lists |
| 557 | |
| 558 | The old perltodo notes that lvalue functions don't work for list or hash |
| 559 | slices. This would be good to fix. |
| 560 | |
| 561 | =head2 LVALUE functions in the debugger |
| 562 | |
| 563 | The old perltodo notes that lvalue functions don't work in the debugger. This |
| 564 | would be good to fix. |
| 565 | |
| 566 | =head2 _ prototype character |
| 567 | |
| 568 | Study the possibility of adding a new prototype character, C<_>, meaning |
| 569 | "this argument defaults to $_". |
| 570 | |
| 571 | =head2 state variables |
| 572 | |
| 573 | C<my $foo if 0;> is deprecated, and should be replaced with |
| 574 | C<state $x = "initial value\n";> the syntax from Perl 6. |
| 575 | |
| 576 | =head2 @INC source filter to Filter::Simple |
| 577 | |
| 578 | The second return value from a sub in @INC can be a source filter. This isn't |
| 579 | documented. It should be changed to use Filter::Simple, tested and documented. |
| 580 | |
| 581 | =head2 regexp optimiser optional |
| 582 | |
| 583 | The regexp optimiser is not optional. It should configurable to be, to allow |
| 584 | its performance to be measured, and its bugs to be easily demonstrated. |
| 585 | |
| 586 | =head2 UNITCHECK |
| 587 | |
| 588 | Introduce a new special block, UNITCHECK, which is run at the end of a |
| 589 | compilation unit (module, file, eval(STRING) block). This will correspond to |
| 590 | the Perl 6 CHECK. Perl 5's CHECK cannot be changed or removed because the |
| 591 | O.pm/B.pm backend framework depends on it. |
| 592 | |
| 593 | =head2 optional optimizer |
| 594 | |
| 595 | Make the peephole optimizer optional. Currently it performs two tasks as |
| 596 | it walks the optree - genuine peephole optimisations, and necessary fixups of |
| 597 | ops. It would be good to find an efficient way to switch out the |
| 598 | optimisations whilst keeping the fixups. |
| 599 | |
| 600 | =head2 You WANT *how* many |
| 601 | |
| 602 | Currently contexts are void, scalar and list. split has a special mechanism in |
| 603 | place to pass in the number of return values wanted. It would be useful to |
| 604 | have a general mechanism for this, backwards compatible and little speed hit. |
| 605 | This would allow proposals such as short circuiting sort to be implemented |
| 606 | as a module on CPAN. |
| 607 | |
| 608 | =head2 lexical aliases |
| 609 | |
| 610 | Allow lexical aliases (maybe via the syntax C<my \$alias = \$foo>. |
| 611 | |
| 612 | =head2 entersub XS vs Perl |
| 613 | |
| 614 | At the moment pp_entersub is huge, and has code to deal with entering both |
| 615 | perl and XS subroutines. Subroutine implementations rarely change between |
| 616 | perl and XS at run time, so investigate using 2 ops to enter subs (one for |
| 617 | XS, one for perl) and swap between if a sub is redefined. |
| 618 | |
| 619 | =head2 Self ties |
| 620 | |
| 621 | self ties are currently illegal because they caused too many segfaults. Maybe |
| 622 | the causes of these could be tracked down and self-ties on all types re- |
| 623 | instated. |
| 624 | |
| 625 | =head2 Optimize away @_ |
| 626 | |
| 627 | The old perltodo notes "Look at the "reification" code in C<av.c>". |
| 628 | |
| 629 | =head2 What hooks would assertions need? |
| 630 | |
| 631 | Assertions are in the core, and work. However, assertions needed to be added |
| 632 | as a core patch, rather than an XS module in ext, or a CPAN module, because |
| 633 | the core has no hooks in the necessary places. It would be useful to |
| 634 | investigate what hooks would need to be added to make it possible to provide |
| 635 | the full assertion support from a CPAN module, so that we aren't constraining |
| 636 | the imagination of future CPAN authors. |
| 637 | |
| 638 | |
| 639 | |
| 640 | |
| 641 | |
| 642 | =head1 Big projects |
| 643 | |
| 644 | Tasks that will get your name mentioned in the description of the "Highlights |
| 645 | of 5.10" |
| 646 | |
| 647 | =head2 make ithreads more robust |
| 648 | |
| 649 | Generally make ithreads more robust. See also L</iCOW> |
| 650 | |
| 651 | This task is incremental - even a little bit of work on it will help, and |
| 652 | will be greatly appreciated. |
| 653 | |
| 654 | =head2 iCOW |
| 655 | |
| 656 | Sarathy and Arthur have a proposal for an improved Copy On Write which |
| 657 | specifically will be able to COW new ithreads. If this can be implemented |
| 658 | it would be a good thing. |
| 659 | |
| 660 | =head2 (?{...}) closures in regexps |
| 661 | |
| 662 | Fix (or rewrite) the implementation of the C</(?{...})/> closures. |
| 663 | |
| 664 | =head2 A re-entrant regexp engine |
| 665 | |
| 666 | This will allow the use of a regex from inside (?{ }), (??{ }) and |
| 667 | (?(?{ })|) constructs. |