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=head1 NAME |
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common::sense - save a tree AND a kitten, use common::sense! |
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=head1 SYNOPSIS |
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use common::sense; |
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|
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# roughly the same as, with much lower memory usage: |
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# |
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# use strict qw(vars subs); |
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# use feature qw(say state switch); |
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# no warnings; |
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# use warnings qw(FATAL closed threads internal debugging pack substr malloc |
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# unopened portable prototype inplace io pipe unpack regexp |
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# deprecated exiting glob digit printf utf8 layer |
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# reserved parenthesis taint closure semicolon); |
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# no warnings qw(exec newline); |
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|
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=head1 DESCRIPTION |
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|
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This module implements some sane defaults for Perl programs, as defined by |
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two typical (or not so typical - use your common sense) specimens of Perl |
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coders. |
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|
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=over 4 |
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|
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=item use strict qw(subs vars) |
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|
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Using C<use strict> is definitely common sense, but C<use strict |
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'refs'> definitely overshoots its usefulness. After almost two |
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decades of Perl hacking, we decided that it does more harm than being |
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useful. Specifically, constructs like these: |
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|
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@{ $var->[0] } |
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|
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Must be written like this (or similarly), when C<use strict 'refs'> is in |
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scope, and C<$var> can legally be C<undef>: |
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@{ $var->[0] || [] } |
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|
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This is annoying, and doesn't shield against obvious mistakes such as |
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using C<"">, so one would even have to write (at least for the time |
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being): |
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|
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@{ defined $var->[0] ? $var->[0] : [] } |
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|
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... which nobody with a bit of common sense would consider |
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writing. |
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|
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Curiously enough, sometimes perl is not so strict, as this works even with |
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C<use strict> in scope: |
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|
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for (@{ $var->[0] }) { ... |
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|
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If that isn't hypocrisy! And all that from a mere program! |
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|
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|
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=item use feature qw(say state given) |
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|
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We found it annoying that we always have to enable extra features. If |
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something breaks because it didn't anticipate future changes, so be |
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it. 5.10 broke almost all our XS modules and nobody cared either (or at |
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least I know of nobody who really complained about gratuitous changes - |
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as opposed to bugs). |
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|
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Few modules that are not actively maintained work with newer versions of |
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Perl, regardless of use feature or not, so a new major perl release means |
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changes to many modules - new keywords are just the tip of the iceberg. |
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If your code isn't alive, it's dead, Jim - be an active maintainer. |
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|
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|
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=item no warnings, but a lot of new errors |
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|
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Ah, the dreaded warnings. Even worse, the horribly dreaded C<-w> |
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switch: Even though we don't care if other people use warnings (and |
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certainly there are useful ones), a lot of warnings simply go against the |
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spirit of Perl. |
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|
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Most prominently, the warnings related to C<undef>. There is nothing wrong |
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with C<undef>: it has well-defined semantics, it is useful, and spitting |
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out warnings you never asked for is just evil. |
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|
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The result was that every one of our modules did C<no warnings> in the |
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past, to avoid somebody accidentally using and forcing his bad standards |
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on our code. Of course, this switched off all warnings, even the useful |
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ones. Not a good situation. Really, the C<-w> switch should only enable |
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warnings for the main program only. |
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|
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Funnily enough, L<perllexwarn> explicitly mentions C<-w> (and not in a |
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favourable way, calling it outright "wrong"), but standard utilities, such |
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as L<prove>, or MakeMaker when running C<make test>, still enable them |
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blindly. |
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|
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For version 2 of common::sense, we finally sat down a few hours and went |
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through I<every single warning message>, identifiying - according to |
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common sense - all the useful ones. |
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|
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This resulted in the rather impressive list in the SYNOPSIS. When we |
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weren't sure, we didn't include the warning, so the list might grow in |
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the future (we might have made a mistake, too, so the list might shrink |
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as well). |
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|
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Note the presence of C<FATAL> in the list: we do not think that the |
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conditions caught by these warnings are worthy of a warning, we I<insist> |
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that they are worthy of I<stopping> your program, I<instantly>. They are |
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I<bugs>! |
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|
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Therefore we consider C<common::sense> to be much stricter than C<use |
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warnings>, which is good if you are into strict things (we are not, |
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actually, but these things tend to be subjective). |
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|
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After deciding on the list, we ran the module against all of our code that |
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uses C<common::sense> (that is almost all of our code), and found only one |
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occurence where one of them caused a problem: one of elmex's (unreleased) |
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modules contained: |
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|
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$fmt =~ s/([^\s\[]*)\[( [^\]]* )\]/\x0$1\x1$2\x0/xgo; |
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We quickly agreed that indeed the code should be changed, even though it |
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happened to do the right thing when the warning was switched off. |
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=item mucho reduced memory usage |
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Just using all those pragmas mentioned in the SYNOPSIS together wastes |
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<blink>I<< B<776> kilobytes >></blink> of precious memory in my perl, for |
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I<every single perl process using our code>, which on our machines, is a |
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lot. In comparison, this module only uses I<< B<four> >> kilobytes (I even |
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had to write it out so it looks like more) of memory on the same platform. |
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|
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The money/time/effort/electricity invested in these gigabytes (probably |
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petabytes globally!) of wasted memory could easily save 42 trees, and a |
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kitten! |
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|
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Unfortunately, until everybods applies more common sense, there will still |
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often be modules that pull in the monster pragmas. But one can hope... |
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|
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=cut |
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package common::sense; |
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our $VERSION = '2.0'; |
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# paste this into pelr to find bitmask |
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# no warnings; |
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# use warnings qw(FATAL closed threads internal debugging pack substr malloc unopened portable prototype |
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# inplace io pipe unpack regexp deprecated exiting glob digit printf |
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# utf8 layer reserved parenthesis taint closure semicolon); |
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# no warnings qw(exec newline); |
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# BEGIN { warn join "", map "\\x$_", unpack "(H2)*", ${^WARNING_BITS}; exit 0 }; |
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# overload should be included |
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sub import { |
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# verified with perl 5.8.0, 5.10.0 |
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${^WARNING_BITS} = "\xfc\x3f\xf3\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x03"; |
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# use strict vars subs |
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$^H |= 0x00000600; |
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# use feature |
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$^H{feature_switch} = |
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$^H{feature_say} = |
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$^H{feature_state} = 1; |
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} |
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1; |
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|
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=back |
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=head1 THERE IS NO 'no common::sense'!!!! !!!! !! |
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This module doesn't offer an unimport. First of all, it wastes even more |
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memory, second, and more importantly, who with even a bit of common sense |
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would want no common sense? |
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=head1 STABILITY AND FUTURE VERSIONS |
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Future versions might change just about everything in this module. We |
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might test our modules and upload new ones working with newer versions of |
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this module, and leave you standing in the rain because we didn't tell |
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you. In fact, we did so when switching from 1.0 to 2.0, which enabled gobs |
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of warnings, and made them FATAL on top. |
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Maybe we will load some nifty modules that try to emulate C<say> or so |
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with perls older than 5.10 (this module, of course, should work with older |
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perl versions - supporting 5.8 for example is just common sense at this |
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time. Maybe not in the future, but of course you can trust our common |
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sense to be consistent with, uhm, our opinion). |
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=head1 WHAT OTHER PEOPLE HAD TO SAY ABOUT THIS MODULE |
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apeiron |
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"... wow" |
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"I hope common::sense is a joke." |
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crab |
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"i wonder how it would be if joerg schilling wrote perl modules." |
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H.Merijn Brand |
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"Just one more reason to drop JSON::XS from my distribution list" |
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Pista Palo |
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"Something in short supply these days..." |
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Steffen Schwigon |
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"This module is quite for sure *not* just a repetition of all the other |
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'use strict, use warnings'-approaches, and it's also not the opposite. |
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[...] And for its chosen middle-way it's also not the worst name ever. |
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And everything is documented." |
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BKB |
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"[Deleted - thanks to Steffen Schwigon for pointing out this review was |
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in error.]" |
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|
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Somni |
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"the arrogance of the guy" |
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"I swear he tacked somenoe else's name onto the module |
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just so he could use the royal 'we' in the documentation" |
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dngor |
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"Heh. '"<elmex at ta-sa.org>"' The quotes are semantic |
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distancing from that e-mail address." |
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Jerad Pierce |
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"Awful name (not a proper pragma), and the SYNOPSIS doesn't tell you |
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anything either. Nor is it clear what features have to do with "common |
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sense" or discipline." |
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acme |
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"THERE IS NO 'no common::sense'!!!! !!!! !!" |
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apeiron (meta-comment about us commenting^Wquoting his comment) |
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How about quoting this: get a clue, you fucktarded amoeba. |
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=head1 AUTHOR |
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|
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Marc Lehmann <schmorp@schmorp.de> |
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http://home.schmorp.de/ |
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Robin Redeker, "<elmex at ta-sa.org>". |
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=cut |
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|