1 | =head1 NAME
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2 |
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3 | perltodo - Perl TO-DO List
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4 |
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5 | =head1 DESCRIPTION
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6 |
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7 | This is a list of wishes for Perl. The tasks we think are smaller or easier
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8 | are listed first. Anyone is welcome to work on any of these, but it's a good
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9 | idea to first contact I<[email protected]> to avoid duplication of
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10 | effort. By all means contact a pumpking privately first if you prefer.
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11 |
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12 | Whilst patches to make the list shorter are most welcome, ideas to add to
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13 | the list are also encouraged. Check the perl5-porters archives for past
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14 | ideas, and any discussion about them. One set of archives may be found at:
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15 |
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16 | http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/
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17 |
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18 | What can we offer you in return? Fame, fortune, and everlasting glory? Maybe
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19 | not, but if your patch is incorporated, then we'll add your name to the
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20 | F<AUTHORS> file, which ships in the official distribution. How many other
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21 | programming languages offer you 1 line of immortality?
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22 |
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23 | =head1 The roadmap to 5.10
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24 |
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25 | The roadmap to 5.10 envisages feature based releases, as various items in this
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26 | TODO are completed.
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27 |
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28 | =head2 Needed for a 5.9.4 release
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29 |
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30 | =over
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31 |
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32 | =item *
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33 |
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34 | Review assertions. Review syntax to combine assertions. Assertions could take
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35 | advantage of the lexical pragmas work. L</What hooks would assertions need?>
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36 |
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37 | =back
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38 |
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39 | =head2 Needed for a 5.9.5 release
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40 |
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41 | =over
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42 |
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43 | =item *
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44 | Implement L</_ prototype character>
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45 |
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46 | =item *
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47 | Implement L</state variables>
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48 |
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49 | =back
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50 |
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51 | =head2 Needed for a 5.9.6 release
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52 |
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53 | Stabilisation. If all goes well, this will be the equivalent of a 5.10-beta.
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54 |
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55 | =head1 Tasks that only need Perl knowledge
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56 |
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57 | =head2 common test code for timed bail out
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58 |
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59 | Write portable self destruct code for tests to stop them burning CPU in
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60 | infinite loops. This needs to avoid using alarm, as some of the tests are
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61 | testing alarm/sleep or timers.
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62 |
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63 | =head2 POD -> HTML conversion in the core still sucks
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64 |
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65 | Which is crazy given just how simple POD purports to be, and how simple HTML
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66 | can be. It's not actually I<as> simple as it sounds, particularly with the
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67 | flexibility POD allows for C<=item>, but it would be good to improve the
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68 | visual appeal of the HTML generated, and to avoid it having any validation
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69 | errors. See also L</make HTML install work>, as the layout of installation tree
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70 | is needed to improve the cross-linking.
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71 |
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72 | The addition of C<Pod::Simple> and its related modules may make this task
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73 | easier to complete.
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74 |
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75 | =head2 Parallel testing
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76 |
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77 | The core regression test suite is getting ever more comprehensive, which has
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78 | the side effect that it takes longer to run. This isn't so good. Investigate
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79 | whether it would be feasible to give the harness script the B<option> of
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80 | running sets of tests in parallel. This would be useful for tests in
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81 | F<t/op/*.t> and F<t/uni/*.t> and maybe some sets of tests in F<lib/>.
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82 |
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83 | Questions to answer
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84 |
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85 | =over 4
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86 |
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87 | =item 1
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88 |
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89 | How does screen layout work when you're running more than one test?
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90 |
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91 | =item 2
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92 |
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93 | How does the caller of test specify how many tests to run in parallel?
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94 |
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95 | =item 3
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96 |
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97 | How do setup/teardown tests identify themselves?
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98 |
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99 | =back
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100 |
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101 | Pugs already does parallel testing - can their approach be re-used?
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102 |
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103 | =head2 Make Schwern poorer
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104 |
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105 | We should have for everything. When all the core's modules are tested,
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106 | Schwern has promised to donate to $500 to TPF. We may need volunteers to
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107 | hold him upside down and shake vigorously in order to actually extract the
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108 | cash.
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109 |
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110 | See F<t/lib/1_compile.t> for the 3 remaining modules that need tests.
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111 |
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112 | =head2 Improve the coverage of the core tests
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113 |
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114 | Use Devel::Cover to ascertain the core's test coverage, then add tests that
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115 | are currently missing.
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116 |
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117 | =head2 test B
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118 |
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119 | A full test suite for the B module would be nice.
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120 |
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121 | =head2 A decent benchmark
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122 |
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123 | C<perlbench> seems impervious to any recent changes made to the perl core. It
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124 | would be useful to have a reasonable general benchmarking suite that roughly
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125 | represented what current perl programs do, and measurably reported whether
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126 | tweaks to the core improve, degrade or don't really affect performance, to
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127 | guide people attempting to optimise the guts of perl. Gisle would welcome
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128 | new tests for perlbench.
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129 |
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130 | =head2 fix tainting bugs
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131 |
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132 | Fix the bugs revealed by running the test suite with the C<-t> switch (via
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133 | C<make test.taintwarn>).
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134 |
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135 | =head2 Dual life everything
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136 |
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137 | As part of the "dists" plan, anything that doesn't belong in the smallest perl
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138 | distribution needs to be dual lifed. Anything else can be too. Figure out what
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139 | changes would be needed to package that module and its tests up for CPAN, and
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140 | do so. Test it with older perl releases, and fix the problems you find.
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141 |
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142 | =head2 Improving C<threads::shared>
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143 |
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144 | Investigate whether C<threads::shared> could share aggregates properly with
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145 | only Perl level changes to shared.pm
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146 |
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147 | =head2 POSIX memory footprint
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148 |
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149 | Ilya observed that use POSIX; eats memory like there's no tomorrow, and at
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150 | various times worked to cut it down. There is probably still fat to cut out -
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151 | for example POSIX passes Exporter some very memory hungry data structures.
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152 |
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153 |
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154 |
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155 |
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156 |
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157 |
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158 |
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159 | =head1 Tasks that need a little sysadmin-type knowledge
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160 |
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161 | Or if you prefer, tasks that you would learn from, and broaden your skills
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162 | base...
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163 |
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164 | =head2 Relocatable perl
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165 |
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166 | The C level patches needed to create a relocatable perl binary are done, as
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167 | is the work on F<Config.pm>. All that's left to do is the C<Configure> tweaking
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168 | to let people specify how they want to do the install.
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169 |
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170 | =head2 make HTML install work
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171 |
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172 | There is an C<installhtml> target in the Makefile. It's marked as
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173 | "experimental". It would be good to get this tested, make it work reliably, and
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174 | remove the "experimental" tag. This would include
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175 |
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176 | =over 4
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177 |
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178 | =item 1
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179 |
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180 | Checking that cross linking between various parts of the documentation works.
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181 | In particular that links work between the modules (files with POD in F<lib/>)
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182 | and the core documentation (files in F<pod/>)
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183 |
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184 | =item 2
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185 |
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186 | Work out how to split C<perlfunc> into chunks, preferably one per function
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187 | group, preferably with general case code that could be used elsewhere.
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188 | Challenges here are correctly identifying the groups of functions that go
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189 | together, and making the right named external cross-links point to the right
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190 | page. Things to be aware of are C<-X>, groups such as C<getpwnam> to
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191 | C<endservent>, two or more C<=items> giving the different parameter lists, such
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192 | as
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193 |
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194 | =item substr EXPR,OFFSET,LENGTH,REPLACEMENT
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195 |
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196 | =item substr EXPR,OFFSET,LENGTH
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197 |
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198 | =item substr EXPR,OFFSET
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199 |
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200 | and different parameter lists having different meanings. (eg C<select>)
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201 |
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202 | =back
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203 |
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204 | =head2 compressed man pages
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205 |
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206 | Be able to install them. This would probably need a configure test to see how
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207 | the system does compressed man pages (same directory/different directory?
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208 | same filename/different filename), as well as tweaking the F<installman> script
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209 | to compress as necessary.
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210 |
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211 | =head2 Add a code coverage target to the Makefile
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212 |
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213 | Make it easy for anyone to run Devel::Cover on the core's tests. The steps
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214 | to do this manually are roughly
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215 |
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216 | =over 4
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217 |
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218 | =item *
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219 |
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220 | do a normal C<Configure>, but include Devel::Cover as a module to install
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221 | (see F<INSTALL> for how to do this)
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222 |
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223 | =item *
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224 |
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225 | make perl
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226 |
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227 | =item *
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228 |
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229 | cd t; HARNESS_PERL_SWITCHES=-MDevel::Cover ./perl -I../lib harness
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230 |
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231 | =item *
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232 |
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233 | Process the resulting Devel::Cover database
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234 |
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235 | =back
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236 |
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237 | This just give you the coverage of the F<.pm>s. To also get the C level
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238 | coverage you need to
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239 |
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240 | =over 4
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241 |
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242 | =item *
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243 |
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244 | Additionally tell C<Configure> to use the appropriate C compiler flags for
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245 | C<gcov>
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246 |
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247 | =item *
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248 |
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249 | make perl.gcov
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250 |
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251 | (instead of C<make perl>)
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252 |
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253 | =item *
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254 |
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255 | After running the tests run C<gcov> to generate all the F<.gcov> files.
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256 | (Including down in the subdirectories of F<ext/>
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257 |
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258 | =item *
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259 |
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260 | (From the top level perl directory) run C<gcov2perl> on all the C<.gcov> files
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261 | to get their stats into the cover_db directory.
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262 |
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263 | =item *
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264 |
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265 | Then process the Devel::Cover database
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266 |
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267 | =back
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268 |
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269 | It would be good to add a single switch to C<Configure> to specify that you
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270 | wanted to perform perl level coverage, and another to specify C level
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271 | coverage, and have C<Configure> and the F<Makefile> do all the right things
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272 | automatically.
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273 |
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274 | =head2 Make Config.pm cope with differences between build and installed perl
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275 |
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276 | Quite often vendors ship a perl binary compiled with their (pay-for)
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277 | compilers. People install a free compiler, such as gcc. To work out how to
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278 | build extensions, Perl interrogates C<%Config>, so in this situation
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279 | C<%Config> describes compilers that aren't there, and extension building
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280 | fails. This forces people into choosing between re-compiling perl themselves
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281 | using the compiler they have, or only using modules that the vendor ships.
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282 |
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283 | It would be good to find a way teach C<Config.pm> about the installation setup,
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284 | possibly involving probing at install time or later, so that the C<%Config> in
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285 | a binary distribution better describes the installed machine, when the
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286 | installed machine differs from the build machine in some significant way.
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287 |
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288 | =head2 make parallel builds work
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289 |
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290 | Currently parallel builds (such as C<make -j3>) don't work reliably. We believe
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291 | that this is due to incomplete dependency specification in the F<Makefile>.
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292 | It would be good if someone were able to track down the causes of these
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293 | problems, so that parallel builds worked properly.
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294 |
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295 | =head2 linker specification files
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296 |
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297 | Some platforms mandate that you provide a list of a shared library's external
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298 | symbols to the linker, so the core already has the infrastructure in place to
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299 | do this for generating shared perl libraries. My understanding is that the
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300 | GNU toolchain can accept an optional linker specification file, and restrict
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301 | visibility just to symbols declared in that file. It would be good to extend
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302 | F<makedef.pl> to support this format, and to provide a means within
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303 | C<Configure> to enable it. This would allow Unix users to test that the
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304 | export list is correct, and to build a perl that does not pollute the global
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305 | namespace with private symbols.
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306 |
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307 |
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308 |
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309 |
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310 | =head1 Tasks that need a little C knowledge
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311 |
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312 | These tasks would need a little C knowledge, but don't need any specific
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313 | background or experience with XS, or how the Perl interpreter works
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314 |
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315 | =head2 Make it clear from -v if this is the exact official release
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316 |
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317 | Currently perl from C<p4>/C<rsync> ships with a F<patchlevel.h> file that
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318 | usually defines one local patch, of the form "MAINT12345" or "RC1". The output
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319 | of perl -v doesn't report that a perl isn't an official release, and this
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320 | information can get lost in bugs reports. Because of this, the minor version
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321 | isn't bumped up until RC time, to minimise the possibility of versions of perl
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322 | escaping that believe themselves to be newer than they actually are.
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323 |
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324 | It would be useful to find an elegant way to have the "this is an interim
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325 | maintenance release" or "this is a release candidate" in the terse -v output,
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326 | and have it so that it's easy for the pumpking to remove this just as the
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327 | release tarball is rolled up. This way the version pulled out of rsync would
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328 | always say "I'm a development release" and it would be safe to bump the
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329 | reported minor version as soon as a release ships, which would aid perl
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330 | developers.
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331 |
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332 | This task is really about thinking of an elegant way to arrange the C source
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333 | such that it's trivial for the Pumpking to flag "this is an official release"
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334 | when making a tarball, yet leave the default source saying "I'm not the
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335 | official release".
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336 |
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337 | =head2 Tidy up global variables
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338 |
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339 | There's a note in F<intrpvar.h>
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340 |
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341 | /* These two variables are needed to preserve 5.8.x bincompat because
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342 | we can't change function prototypes of two exported functions.
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343 | Probably should be taken out of blead soon, and relevant prototypes
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344 | changed. */
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345 |
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346 | So doing this, and removing any of the unused variables still present would
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347 | be good.
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348 |
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349 | =head2 Ordering of "global" variables.
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350 |
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351 | F<thrdvar.h> and F<intrpvarh> define the "global" variables that need to be
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352 | per-thread under ithreads, where the variables are actually elements in a
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353 | structure. As C dictates, the variables must be laid out in order of
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354 | declaration. There is a comment
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355 | C</* Important ones in the first cache line (if alignment is done right) */>
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356 | which implies that at some point in the past the ordering was carefully chosen
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357 | (at least in part). However, it's clear that the ordering is less than perfect,
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358 | as currently there are things such as 7 C<bool>s in a row, then something
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359 | typically requiring 4 byte alignment, and then an odd C<bool> later on.
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360 | (C<bool>s are typically defined as C<char>s). So it would be good for someone
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361 | to review the ordering of the variables, to see how much alignment padding can
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362 | be removed.
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363 |
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364 | =head2 bincompat functions
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365 |
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366 | There are lots of functions which are retained for binary compatibility.
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367 | Clean these up. Move them to mathom.c, and don't compile for blead?
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368 |
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369 | =head2 am I hot or not?
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370 |
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371 | The idea of F<pp_hot.c> is that it contains the I<hot> ops, the ops that are
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372 | most commonly used. The idea is that by grouping them, their object code will
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373 | be adjacent in the executable, so they have a greater chance of already being
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374 | in the CPU cache (or swapped in) due to being near another op already in use.
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375 |
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376 | Except that it's not clear if these really are the most commonly used ops. So
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377 | anyone feeling like exercising their skill with coverage and profiling tools
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378 | might want to determine what ops I<really> are the most commonly used. And in
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379 | turn suggest evictions and promotions to achieve a better F<pp_hot.c>.
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380 |
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381 | =head2 emulate the per-thread memory pool on Unix
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382 |
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383 | For Windows, ithreads allocates memory for each thread from a separate pool,
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384 | which it discards at thread exit. It also checks that memory is free()d to
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385 | the correct pool. Neither check is done on Unix, so code developed there won't
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386 | be subject to such strictures, so can harbour bugs that only show up when the
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387 | code reaches Windows.
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388 |
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389 | It would be good to be able to optionally emulate the Window pool system on
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390 | Unix, to let developers who only have access to Unix, or want to use
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391 | Unix-specific debugging tools, check for these problems. To do this would
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392 | involve figuring out how the C<PerlMem_*> macros wrap C<malloc()> access, and
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393 | providing a layer that records/checks the identity of the thread making the
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394 | call, and recording all the memory allocated by each thread via this API so
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395 | that it can be summarily free()d at thread exit. One implementation idea
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396 | would be to increase the size of allocation, and store the C<my_perl> pointer
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397 | (to identify the thread) at the start, along with pointers to make a linked
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398 | list of blocks for this thread. To avoid alignment problems it would be
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399 | necessary to do something like
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400 |
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401 | union memory_header_padded {
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402 | struct memory_header {
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403 | void *thread_id; /* For my_perl */
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404 | void *next; /* Pointer to next block for this thread */
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405 | } data;
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406 | long double padding; /* whatever type has maximal alignment constraint */
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407 | };
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408 |
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409 |
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410 | although C<long double> might not be the only type to add to the padding
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411 | union.
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412 |
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413 | =head2 reduce duplication in sv_setsv_flags
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414 |
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415 | C<Perl_sv_setsv_flags> has a comment
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416 | C</* There's a lot of redundancy below but we're going for speed here */>
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417 |
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418 | Whilst this was true 10 years ago, the growing disparity between RAM and CPU
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419 | speeds mean that the trade offs have changed. In addition, the duplicate code
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420 | adds to the maintenance burden. It would be good to see how much of the
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421 | redundancy can be pruned, particular in the less common paths. (Profiling
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422 | tools at the ready...). For example, why does the test for
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423 | "Can't redefine active sort subroutine" need to occur in two places?
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424 |
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425 |
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426 |
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427 |
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428 | =head1 Tasks that need a knowledge of XS
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429 |
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430 | These tasks would need C knowledge, and roughly the level of knowledge of
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431 | the perl API that comes from writing modules that use XS to interface to
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432 | C.
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433 |
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434 | =head2 IPv6
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435 |
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436 | Clean this up. Check everything in core works
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437 |
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438 | =head2 shrink C<GV>s, C<CV>s
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439 |
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440 | By removing unused elements and careful re-ordering, the structures for C<AV>s
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441 | and C<HV>s have recently been shrunk considerably. It's probable that the same
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442 | approach would find savings in C<GV>s and C<CV>s, if not all the other
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443 | larger-than-C<PVMG> types.
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444 |
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445 | =head2 merge Perl_sv_2[inpu]v
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446 |
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447 | There's a lot of code shared between C<Perl_sv_2iv_flags>,
|
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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.
|
---|