| 1 | #! perl |
1 | #! perl-000 |
| 2 | |
2 | |
| 3 | open STDOUT, ">$ARGV[0]~" |
3 | open STDOUT, ">$ARGV[0]~" |
| 4 | or die "$ARGV[0]~: $!"; |
4 | or die "$ARGV[0]~: $!"; |
| 5 | |
5 | |
| 6 | our $WARN; |
6 | our ($WARN, $H, %H); |
| 7 | our $H; |
7 | |
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8 | use utf8; |
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9 | use strict qw(subs vars); |
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10 | |
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11 | BEGIN { |
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12 | if ($] >= 5.010) { |
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13 | require feature; |
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14 | feature->import (qw(say state switch)); |
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15 | } |
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16 | if ($] >= 5.012) { |
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17 | feature->import (qw(unicode_strings)); |
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18 | } |
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19 | if ($] >= 5.016) { |
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20 | feature->import (qw(current_sub fc evalbytes)); |
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21 | feature->unimport (qw(array_base)); |
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22 | } |
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23 | } |
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24 | |
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25 | no warnings; |
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26 | use warnings qw(FATAL closed threads internal debugging pack malloc portable prototype |
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27 | inplace io pipe unpack deprecated glob digit printf |
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28 | layer reserved taint closure semicolon); |
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29 | no warnings qw(exec newline unopened); |
| 8 | |
30 | |
| 9 | BEGIN { |
31 | BEGIN { |
| 10 | $H = $^H; |
32 | $H = $^H; |
| 11 | $WARN = ${^WARNING_BITS}; |
33 | $WARN = ${^WARNING_BITS}; |
| 12 | } |
34 | %H = %^H; |
| 13 | |
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| 14 | use utf8; |
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| 15 | use strict qw(subs vars); |
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| 16 | |
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| 17 | no warnings; |
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| 18 | use warnings qw(FATAL closed threads internal debugging pack malloc portable prototype |
|
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| 19 | inplace io pipe unpack regexp deprecated exiting glob digit printf |
|
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| 20 | layer reserved taint closure semicolon); |
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| 21 | no warnings qw(exec newline unopened); |
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| 22 | |
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| 23 | BEGIN { |
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| 24 | $H = $^H & ~$H; |
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| 25 | $WARN = ${^WARNING_BITS} & ~$WARN; |
|
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| 26 | } |
35 | } |
| 27 | |
36 | |
| 28 | while (<DATA>) { |
37 | while (<DATA>) { |
| 29 | if (/^IMPORT/) { |
38 | if (/^IMPORT/) { |
| 30 | print " # use warnings\n"; |
39 | print " # use warnings\n"; |
| 31 | printf " \${^WARNING_BITS} ^= \${^WARNING_BITS} ^ \"%s\";\n", |
40 | printf " \${^WARNING_BITS} ^= \${^WARNING_BITS} ^ \"%s\";\n", |
| 32 | join "", map "\\x$_", unpack "(H2)*", $WARN; |
41 | join "", map "\\x$_", unpack "(H2)*", $WARN; |
| 33 | print " # use strict, use utf8;\n"; |
42 | print " # use strict, use utf8; use feature;\n"; |
| 34 | printf " \$^H |= 0x%x;\n", $H; |
43 | printf " \$^H |= 0x%x;\n", $H; |
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44 | |
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45 | if (my @features = grep /^feature_/, keys %H) { |
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46 | print " \@^H{qw(@features)} = (1) x ", (scalar @features), ";\n"; |
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47 | } |
| 35 | } else { |
48 | } else { |
| 36 | print; |
49 | print; |
| 37 | } |
50 | } |
| 38 | } |
51 | } |
| 39 | |
52 | |
| 40 | close STDOUT; |
53 | close STDOUT; |
| 41 | rename "$ARGV[0]~", $ARGV[0]; |
54 | rename "$ARGV[0]~", $ARGV[0]; |
| 42 | |
55 | |
| 43 | __DATA__ |
56 | __DATA__ |
| 44 | |
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| 45 | =head1 NAME |
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| 46 | |
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| 47 | common::sense - save a tree AND a kitten, use common::sense! |
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| 48 | |
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| 49 | =head1 SYNOPSIS |
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| 50 | |
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| 51 | use common::sense; |
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| 52 | |
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| 53 | # supposed to be the same, with much lower memory usage, as: |
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| 54 | # |
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| 55 | # use utf8; |
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| 56 | # use strict qw(vars subs); |
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| 57 | # use feature qw(say state switch); |
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| 58 | # no warnings; |
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| 59 | # use warnings qw(FATAL closed threads internal debugging pack malloc |
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| 60 | # portable prototype inplace io pipe unpack regexp |
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| 61 | # deprecated exiting glob digit printf layer |
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| 62 | # reserved taint closure semicolon); |
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| 63 | # no warnings qw(exec newline unopened); |
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| 64 | |
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| 65 | =head1 DESCRIPTION |
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| 66 | |
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| 67 | This module implements some sane defaults for Perl programs, as defined by |
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| 68 | two typical (or not so typical - use your common sense) specimens of Perl |
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| 69 | coders. In fact, after working out details on which warnings and strict |
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| 70 | modes to enable and make fatal, we found that we (and our code written so |
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| 71 | far, and others) fully agree on every option, even though we never used |
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| 72 | warnings before, so it seems this module indeed reflects a "common" sense |
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| 73 | among some long-time Perl coders. |
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| 74 | |
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| 75 | The basic philosophy behind the choices made in common::sense can be |
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| 76 | summarised as: "enforcing strict policies to catch as many bugs as |
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| 77 | possible, while at the same time, not limiting the expressive power |
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| 78 | available to the programmer". |
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| 79 | |
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| 80 | Two typical examples of how this philosophy is applied in practise is the |
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| 81 | handling of uninitialised and malloc warnings: |
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| 82 | |
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| 83 | =over 4 |
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| 84 | |
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| 85 | =item I<uninitialised> |
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| 86 | |
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| 87 | C<undef> is a well-defined feature of perl, and enabling warnings for |
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| 88 | using it rarely catches any bugs, but considerably limits you in what you |
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| 89 | can do, so uninitialised warnings are disabled. |
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| 90 | |
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| 91 | =item I<malloc> |
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| 92 | |
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| 93 | Freeing something twice on the C level is a serious bug, usually causing |
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| 94 | memory corruption. It often leads to side effects much later in the |
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| 95 | program and there are no advantages to not reporting this, so malloc |
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| 96 | warnings are fatal by default. |
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| 97 | |
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| 98 | =back |
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| 99 | |
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| 100 | What follows is a more thorough discussion of what this module does, |
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| 101 | and why it does it, and what the advantages (and disadvantages) of this |
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| 102 | approach are. |
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| 103 | |
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| 104 | =head1 RATIONALE |
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| 105 | |
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| 106 | =over 4 |
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| 107 | |
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| 108 | =item use utf8 |
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| 109 | |
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| 110 | While it's not common sense to write your programs in UTF-8, it's quickly |
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| 111 | becoming the most common encoding, is the designated future default |
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| 112 | encoding for perl sources, and the most convenient encoding available |
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| 113 | (you can do really nice quoting tricks...). Experience has shown that our |
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| 114 | programs were either all pure ascii or utf-8, both of which will stay the |
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| 115 | same. |
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| 116 | |
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| 117 | There are few drawbacks to enabling UTF-8 source code by default (mainly |
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| 118 | some speed hits due to bugs in older versions of perl), so this module |
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| 119 | enables UTF-8 source code encoding by default. |
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| 120 | |
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| 121 | |
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| 122 | =item use strict qw(subs vars) |
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| 123 | |
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| 124 | Using C<use strict> is definitely common sense, but C<use strict |
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| 125 | 'refs'> definitely overshoots its usefulness. After almost two |
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| 126 | decades of Perl hacking, we decided that it does more harm than being |
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| 127 | useful. Specifically, constructs like these: |
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| 128 | |
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| 129 | @{ $var->[0] } |
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| 130 | |
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| 131 | Must be written like this (or similarly), when C<use strict 'refs'> is in |
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| 132 | scope, and C<$var> can legally be C<undef>: |
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| 133 | |
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| 134 | @{ $var->[0] || [] } |
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| 135 | |
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| 136 | This is annoying, and doesn't shield against obvious mistakes such as |
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| 137 | using C<"">, so one would even have to write (at least for the time |
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| 138 | being): |
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| 139 | |
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| 140 | @{ defined $var->[0] ? $var->[0] : [] } |
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| 141 | |
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| 142 | ... which nobody with a bit of common sense would consider |
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| 143 | writing: clear code is clearly something else. |
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| 144 | |
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| 145 | Curiously enough, sometimes perl is not so strict, as this works even with |
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| 146 | C<use strict> in scope: |
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| 147 | |
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| 148 | for (@{ $var->[0] }) { ... |
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| 149 | |
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| 150 | If that isn't hypocrisy! And all that from a mere program! |
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| 151 | |
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| 152 | |
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| 153 | =item use feature qw(say state given) |
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| 154 | |
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| 155 | We found it annoying that we always have to enable extra features. If |
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| 156 | something breaks because it didn't anticipate future changes, so be |
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| 157 | it. 5.10 broke almost all our XS modules and nobody cared either (or at |
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| 158 | least I know of nobody who really complained about gratuitous changes - |
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| 159 | as opposed to bugs). |
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| 160 | |
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| 161 | Few modules that are not actively maintained work with newer versions of |
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| 162 | Perl, regardless of use feature or not, so a new major perl release means |
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| 163 | changes to many modules - new keywords are just the tip of the iceberg. |
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| 164 | |
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| 165 | If your code isn't alive, it's dead, Jim - be an active maintainer. |
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| 166 | |
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| 167 | But nobody forces you to use those extra features in modules meant for |
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| 168 | older versions of perl - common::sense of course works there as well. |
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| 169 | There is also an important other mode where having additional features by |
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| 170 | default is useful: commandline hacks and internal use scripts: See "much |
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| 171 | reduced typing", below. |
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| 172 | |
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| 173 | |
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| 174 | =item no warnings, but a lot of new errors |
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| 175 | |
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| 176 | Ah, the dreaded warnings. Even worse, the horribly dreaded C<-w> |
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| 177 | switch: Even though we don't care if other people use warnings (and |
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| 178 | certainly there are useful ones), a lot of warnings simply go against the |
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| 179 | spirit of Perl. |
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| 180 | |
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| 181 | Most prominently, the warnings related to C<undef>. There is nothing wrong |
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| 182 | with C<undef>: it has well-defined semantics, it is useful, and spitting |
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| 183 | out warnings you never asked for is just evil. |
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| 184 | |
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| 185 | The result was that every one of our modules did C<no warnings> in the |
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| 186 | past, to avoid somebody accidentally using and forcing his bad standards |
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| 187 | on our code. Of course, this switched off all warnings, even the useful |
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| 188 | ones. Not a good situation. Really, the C<-w> switch should only enable |
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| 189 | warnings for the main program only. |
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| 190 | |
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| 191 | Funnily enough, L<perllexwarn> explicitly mentions C<-w> (and not in a |
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| 192 | favourable way, calling it outright "wrong"), but standard utilities, such |
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| 193 | as L<prove>, or MakeMaker when running C<make test>, still enable them |
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| 194 | blindly. |
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| 195 | |
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| 196 | For version 2 of common::sense, we finally sat down a few hours and went |
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| 197 | through I<every single warning message>, identifiying - according to |
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| 198 | common sense - all the useful ones. |
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| 199 | |
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| 200 | This resulted in the rather impressive list in the SYNOPSIS. When we |
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| 201 | weren't sure, we didn't include the warning, so the list might grow in |
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| 202 | the future (we might have made a mistake, too, so the list might shrink |
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| 203 | as well). |
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| 204 | |
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| 205 | Note the presence of C<FATAL> in the list: we do not think that the |
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| 206 | conditions caught by these warnings are worthy of a warning, we I<insist> |
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| 207 | that they are worthy of I<stopping> your program, I<instantly>. They are |
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| 208 | I<bugs>! |
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| 209 | |
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| 210 | Therefore we consider C<common::sense> to be much stricter than C<use |
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| 211 | warnings>, which is good if you are into strict things (we are not, |
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| 212 | actually, but these things tend to be subjective). |
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| 213 | |
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| 214 | After deciding on the list, we ran the module against all of our code that |
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| 215 | uses C<common::sense> (that is almost all of our code), and found only one |
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| 216 | occurence where one of them caused a problem: one of elmex's (unreleased) |
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| 217 | modules contained: |
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| 218 | |
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| 219 | $fmt =~ s/([^\s\[]*)\[( [^\]]* )\]/\x0$1\x1$2\x0/xgo; |
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| 220 | |
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| 221 | We quickly agreed that indeed the code should be changed, even though it |
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| 222 | happened to do the right thing when the warning was switched off. |
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| 223 | |
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| 224 | |
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| 225 | =item much reduced typing |
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| 226 | |
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| 227 | Especially with version 2.0 of common::sense, the amount of boilerplate |
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| 228 | code you need to add to gte I<this> policy is daunting. Nobody would write |
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| 229 | this out in throwaway scripts, commandline hacks or in quick internal-use |
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| 230 | scripts. |
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| 231 | |
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| 232 | By using common::sense you get a defined set of policies (ours, but maybe |
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| 233 | yours, too, if you accept them), and they are easy to apply to your |
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| 234 | scripts: typing C<use common::sense;> is even shorter than C<use warnings; |
|
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| 235 | use strict; use feature ...>. |
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| 236 | |
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| 237 | And you can immediately use the features of your installed perl, which |
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| 238 | is more difficult in code you release, but not usually an issue for |
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| 239 | internal-use code (downgrades of your production perl should be rare, |
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| 240 | right?). |
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| 241 | |
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| 242 | |
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| 243 | =item mucho reduced memory usage |
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| 244 | |
|
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| 245 | Just using all those pragmas mentioned in the SYNOPSIS together wastes |
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| 246 | <blink>I<< B<776> kilobytes >></blink> of precious memory in my perl, for |
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| 247 | I<every single perl process using our code>, which on our machines, is a |
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| 248 | lot. In comparison, this module only uses I<< B<four> >> kilobytes (I even |
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| 249 | had to write it out so it looks like more) of memory on the same platform. |
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| 250 | |
|
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| 251 | The money/time/effort/electricity invested in these gigabytes (probably |
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| 252 | petabytes globally!) of wasted memory could easily save 42 trees, and a |
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| 253 | kitten! |
|
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| 254 | |
|
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| 255 | Unfortunately, until everybods applies more common sense, there will still |
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| 256 | often be modules that pull in the monster pragmas. But one can hope... |
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| 257 | |
|
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| 258 | =cut |
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| 259 | |
|
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| 260 | package common::sense; |
57 | package common::sense; |
| 261 | |
58 | |
| 262 | our $VERSION = '3.2'; |
59 | our $VERSION = '3.7'; |
| 263 | |
60 | |
| 264 | # overload should be included |
61 | # overload should be included |
| 265 | |
62 | |
| 266 | sub import { |
63 | sub import { |
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64 | local $^W; # work around perl 5.16 spewing out warnings for next statement |
| 267 | IMPORT |
65 | IMPORT |
| 268 | # use feature |
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| 269 | $^H{feature_switch} = |
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| 270 | $^H{feature_say} = |
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| 271 | $^H{feature_state} = 1; |
|
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| 272 | } |
66 | } |
| 273 | |
67 | |
| 274 | 1; |
68 | 1 |
| 275 | |
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| 276 | =back |
|
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| 277 | |
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| 278 | =head1 THERE IS NO 'no common::sense'!!!! !!!! !! |
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| 279 | |
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| 280 | This module doesn't offer an unimport. First of all, it wastes even more |
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| 281 | memory, second, and more importantly, who with even a bit of common sense |
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| 282 | would want no common sense? |
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| 283 | |
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| 284 | =head1 STABILITY AND FUTURE VERSIONS |
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| 285 | |
|
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| 286 | Future versions might change just about everything in this module. We |
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| 287 | might test our modules and upload new ones working with newer versions of |
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| 288 | this module, and leave you standing in the rain because we didn't tell |
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| 289 | you. In fact, we did so when switching from 1.0 to 2.0, which enabled gobs |
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| 290 | of warnings, and made them FATAL on top. |
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| 291 | |
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| 292 | Maybe we will load some nifty modules that try to emulate C<say> or so |
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| 293 | with perls older than 5.10 (this module, of course, should work with older |
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| 294 | perl versions - supporting 5.8 for example is just common sense at this |
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| 295 | time. Maybe not in the future, but of course you can trust our common |
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| 296 | sense to be consistent with, uhm, our opinion). |
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| 297 | |
|
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| 298 | =head1 WHAT OTHER PEOPLE HAD TO SAY ABOUT THIS MODULE |
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| 299 | |
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| 300 | apeiron |
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| 301 | |
|
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| 302 | "... wow" |
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| 303 | "I hope common::sense is a joke." |
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| 304 | |
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| 305 | crab |
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| 306 | |
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| 307 | "i wonder how it would be if joerg schilling wrote perl modules." |
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| 308 | |
|
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| 309 | Adam Kennedy |
|
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| 310 | |
|
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| 311 | "Very interesting, efficient, and potentially something I'd use all the time." |
|
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| 312 | [...] |
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| 313 | "So no common::sense for me, alas." |
|
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| 314 | |
|
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| 315 | H.Merijn Brand |
|
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| 316 | |
|
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| 317 | "Just one more reason to drop JSON::XS from my distribution list" |
|
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| 318 | |
|
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| 319 | Pista Palo |
|
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| 320 | |
|
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| 321 | "Something in short supply these days..." |
|
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| 322 | |
|
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| 323 | Steffen Schwigon |
|
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| 324 | |
|
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| 325 | "This module is quite for sure *not* just a repetition of all the other |
|
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| 326 | 'use strict, use warnings'-approaches, and it's also not the opposite. |
|
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| 327 | [...] And for its chosen middle-way it's also not the worst name ever. |
|
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| 328 | And everything is documented." |
|
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| 329 | |
|
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| 330 | BKB |
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| 331 | |
|
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| 332 | "[Deleted - thanks to Steffen Schwigon for pointing out this review was |
|
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| 333 | in error.]" |
|
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| 334 | |
|
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| 335 | Somni |
|
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| 336 | |
|
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| 337 | "the arrogance of the guy" |
|
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| 338 | "I swear he tacked somenoe else's name onto the module |
|
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| 339 | just so he could use the royal 'we' in the documentation" |
|
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| 340 | |
|
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| 341 | Anonymous Monk |
|
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| 342 | |
|
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| 343 | "You just gotta love this thing, its got META.json!!!" |
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| 344 | |
|
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| 345 | dngor |
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| 346 | |
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| 347 | "Heh. '"<elmex at ta-sa.org>"' The quotes are semantic |
|
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| 348 | distancing from that e-mail address." |
|
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| 349 | |
|
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| 350 | Jerad Pierce |
|
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| 351 | |
|
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| 352 | "Awful name (not a proper pragma), and the SYNOPSIS doesn't tell you |
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| 353 | anything either. Nor is it clear what features have to do with "common |
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| 354 | sense" or discipline." |
|
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| 355 | |
|
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| 356 | acme |
|
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| 357 | |
|
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| 358 | "THERE IS NO 'no common::sense'!!!! !!!! !!" |
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| 359 | |
|
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| 360 | apeiron (meta-comment about us commenting^Wquoting his comment) |
|
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| 361 | |
|
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| 362 | "How about quoting this: get a clue, you fucktarded amoeba." |
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| 363 | |
|
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| 364 | quanth |
|
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| 365 | |
|
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| 366 | "common sense is beautiful, json::xs is fast, Anyevent, EV are fast and |
|
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| 367 | furious. I love mlehmannware ;)" |
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| 368 | |
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| 369 | apeiron |
|
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| 370 | |
|
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| 371 | "... it's mlehmann's view of what common sense is. His view of common |
|
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| 372 | sense is certainly uncommon, insofar as anyone with a clue disagrees |
|
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| 373 | with him." |
|
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| 374 | |
|
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| 375 | apeiron (another meta-comment) |
|
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| 376 | |
|
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| 377 | "apeiron wonders if his little informant is here to steal more quotes" |
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| 378 | |
|
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| 379 | ew73 |
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| 380 | |
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| 381 | "... I never got past the SYNOPSIS before calling it shit." |
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| 382 | [...] |
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| 383 | How come no one ever quotes me. :(" |
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| 384 | |
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| 385 | =head1 FREQUENTLY ASKED QUESTIONS |
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| 386 | |
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| 387 | Or frequently-come-up confusions. |
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| 388 | |
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| 389 | =over 4 |
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| 390 | |
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| 391 | =item Is this module meant to be serious? |
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| 392 | |
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| 393 | Yes, we would have put it under the C<Acme::> namespace otherwise. |
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| 394 | |
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| 395 | =item But the manpage is written in a funny/stupid/... way? |
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| 396 | |
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| 397 | This was meant to make it clear that our common sense is a subjective |
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| 398 | thing and other people can use their own notions, taking the steam out |
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| 399 | of anybody who might be offended (as some people are always offended no |
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| 400 | matter what you do). |
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| 401 | |
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| 402 | This was a failure. |
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| 403 | |
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| 404 | But we hope the manpage still is somewhat entertaining even though it |
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| 405 | explains boring rationale. |
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| 406 | |
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| 407 | =item Why do you impose your conventions on my code? |
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| 408 | |
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| 409 | For some reason people keep thinking that C<common::sense> imposes |
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| 410 | process-wide limits, even though the SYNOPSIS makes it clear that it works |
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| 411 | like other similar modules - i.e. only within the scope that C<use>s them. |
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| 412 | |
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| 413 | So, no, we don't - nobody is forced to use this module, and using a module |
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| 414 | that relies on common::sense does not impose anything on you. |
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| 415 | |
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| 416 | =item Why do you think only your notion of common::sense is valid? |
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| 417 | |
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| 418 | Well, we don't, and have clearly written this in the documentation to |
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| 419 | every single release. We were just faster than anybody else w.r.t. to |
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| 420 | grabbing the namespace. |
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| 421 | |
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| 422 | =item But everybody knows that you have to use strict and use warnings, |
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| 423 | why do you disable them? |
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| 424 | |
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| 425 | Well, we don't do this either - we selectively disagree with the |
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| 426 | usefulness of some warnings over others. This module is aimed at |
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| 427 | experienced Perl programmers, not people migrating from other languages |
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| 428 | who might be surprised about stuff such as C<undef>. On the other hand, |
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| 429 | this does not exclude the usefulness of this module for total newbies, due |
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| 430 | to its strictness in enforcing policy, while at the same time not limiting |
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| 431 | the expresive power of perl. |
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| 432 | |
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| 433 | This module is considerably I<more> strict than the canonical C<use |
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| 434 | strict; use warnings>, as it makes all its warnings fatal in nature, so |
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| 435 | you can not get away with as many things as with the canonical approach. |
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| 436 | |
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| 437 | This was not implemented in version 1.0 because of the daunting number |
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| 438 | of warning categories and the difficulty in getting exactly the set of |
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| 439 | warnings you wish (i.e. look at the SYNOPSIS in how complicated it is to |
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| 440 | get a specific set of warnings - it is not reasonable to put this into |
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| 441 | every module, the maintenance effort would be enourmous). |
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| 442 | |
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| 443 | =item But many modules C<use strict> or C<use warnings>, so the memory |
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| 444 | savings do not apply? |
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| 445 | |
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| 446 | I suddenly feel sad... |
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| 447 | |
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| 448 | But yes, that's true. Fortunately C<common::sense> still uses only a |
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| 449 | miniscule amount of RAM. |
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| 450 | |
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| 451 | =item But it adds another dependency to your modules! |
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| 452 | |
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| 453 | It's a fact, yeah. But it's trivial to install, most popular modules have |
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| 454 | many more dependencies and we consider dependencies a good thing - it |
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| 455 | leads to better APIs, more thought about interworking of modules and so |
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| 456 | on. |
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| 457 | |
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| 458 | =item Why do you use JSON and not YAML for your META.yml? |
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| 459 | |
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| 460 | This is not true - YAML supports a large subset of JSON, and this subset |
|
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| 461 | is what META.yml is written in, so it would be correct to say "the |
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| 462 | META.yml is written in a common subset of YAML and JSON". |
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| 463 | |
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| 464 | The META.yml follows the YAML, JSON and META.yml specifications, and is |
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| 465 | correctly parsed by CPAN, so if you have trouble with it, the problem is |
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| 466 | likely on your side. |
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| 467 | |
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| 468 | =item But! But! |
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| 469 | |
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| 470 | Yeah, we know. |
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| 471 | |
|
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| 472 | =back |
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| 473 | |
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| 474 | =head1 AUTHOR |
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| 475 | |
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| 476 | Marc Lehmann <schmorp@schmorp.de> |
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| 477 | http://home.schmorp.de/ |
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| 478 | |
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| 479 | Robin Redeker, "<elmex at ta-sa.org>". |
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| 480 | |
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| 481 | =cut |
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| 482 | |
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|
