Initial Commit

database/perl/vendor/lib/common/sense.pm

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+package common::sense;
+
+our $VERSION = 3.75;
+
+# overload should be included
+
+sub import {
+   local $^W; # work around perl 5.16 spewing out warnings for next statement
+   # use warnings
+   ${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\x0c\x3f\x33\x00\x03\xf0\x0f\xc0\xf0\xfc\x33\x00\x00\x00\x0c\x00\x00\x00\x00";
+   # use strict, use utf8; use feature;
+   $^H |= 0x1c820fc0;
+   @^H{qw(feature___SUB__ feature_evalbytes feature_fc feature_indirect feature_say feature_state feature_switch feature_unicode)} = (1) x 8;
+}
+
+1

database/perl/vendor/lib/common/sense.pod

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+=head1 NAME
+
+common::sense - save a tree AND a kitten, use common::sense!
+
+=head1 SYNOPSIS
+
+   use common::sense;
+
+   # Supposed to be mostly the same, with much lower memory usage, as:
+  
+   # use utf8;
+   # use strict qw(vars subs);
+   # use feature qw(say state switch);
+   # use feature qw(unicode_strings unicode_eval current_sub fc evalbytes);
+   # no feature qw(array_base);
+   # no warnings;
+   # use warnings qw(FATAL closed threads internal debugging pack
+   #                 prototype inplace io pipe unpack malloc glob
+   #                 digit printf layer reserved taint closure semicolon);
+   # no warnings qw(exec newline unopened);
+
+=head1 DESCRIPTION
+
+   “Nothing is more fairly distributed than common sense: no one thinks
+   he needs more of it than he already has.”
+
+   – René Descartes
+
+This module implements some sane defaults for Perl programs, as defined by
+two typical (or not so typical - use your common sense) specimens of Perl
+coders. In fact, after working out details on which warnings and strict
+modes to enable and make fatal, we found that we (and our code written so
+far, and others) fully agree on every option, even though we never used
+warnings before, so it seems this module indeed reflects a "common" sense
+among some long-time Perl coders.
+
+The basic philosophy behind the choices made in common::sense can be
+summarised as: "enforcing strict policies to catch as many bugs as
+possible, while at the same time, not limiting the expressive power
+available to the programmer".
+
+Two typical examples of how this philosophy is applied in practise is the
+handling of uninitialised and malloc warnings:
+
+=over 4
+
+=item I<uninitialised>
+
+C<undef> is a well-defined feature of perl, and enabling warnings for
+using it rarely catches any bugs, but considerably limits you in what you
+can do, so uninitialised warnings are disabled.
+
+=item I<malloc>
+
+Freeing something twice on the C level is a serious bug, usually causing
+memory corruption. It often leads to side effects much later in the
+program and there are no advantages to not reporting this, so malloc
+warnings are fatal by default.
+
+=back
+
+Unfortunately, there is no fine-grained warning control in perl, so often
+whole groups of useful warnings had to be excluded because of a single
+useless warning (for example, perl puts an arbitrary limit on the length
+of text you can match with some regexes before emitting a warning, making
+the whole C<regexp> category useless).
+
+What follows is a more thorough discussion of what this module does,
+and why it does it, and what the advantages (and disadvantages) of this
+approach are.
+
+=head1 RATIONALE
+
+=over 4
+
+=item use utf8
+
+While it's not common sense to write your programs in UTF-8, it's quickly
+becoming the most common encoding, is the designated future default
+encoding for perl sources, and the most convenient encoding available
+(you can do really nice quoting tricks...). Experience has shown that our
+programs were either all pure ascii or utf-8, both of which will stay the
+same.
+
+There are few drawbacks to enabling UTF-8 source code by default (mainly
+some speed hits due to bugs in older versions of perl), so this module
+enables UTF-8 source code encoding by default.
+
+
+=item use strict qw(subs vars)
+
+Using C<use strict> is definitely common sense, but C<use strict
+'refs'> definitely overshoots its usefulness. After almost two
+decades of Perl hacking, we decided that it does more harm than being
+useful. Specifically, constructs like these:
+
+   @{ $var->[0] }
+
+Must be written like this (or similarly), when C<use strict 'refs'> is in
+scope, and C<$var> can legally be C<undef>:
+
+   @{ $var->[0] || [] }
+
+This is annoying, and doesn't shield against obvious mistakes such as
+using C<"">, so one would even have to write (at least for the time
+being):
+
+   @{ defined $var->[0] ? $var->[0] : [] }
+
+... which nobody with a bit of common sense would consider
+writing: clear code is clearly something else.
+
+Curiously enough, sometimes perl is not so strict, as this works even with
+C<use strict> in scope:
+
+   for (@{ $var->[0] }) { ...
+
+If that isn't hypocrisy! And all that from a mere program!
+
+
+=item use feature qw(say state given ...)
+
+We found it annoying that we always have to enable extra features. If
+something breaks because it didn't anticipate future changes, so be
+it. 5.10 broke almost all our XS modules and nobody cared either (or at
+least I know of nobody who really complained about gratuitous changes -
+as opposed to bugs).
+
+Few modules that are not actively maintained work with newer versions of
+Perl, regardless of use feature or not, so a new major perl release means
+changes to many modules - new keywords are just the tip of the iceberg.
+
+If your code isn't alive, it's dead, Jim - be an active maintainer.
+
+But nobody forces you to use those extra features in modules meant for
+older versions of perl - common::sense of course works there as well.
+There is also an important other mode where having additional features by
+default is useful: commandline hacks and internal use scripts: See "much
+reduced typing", below.
+
+There is one notable exception: C<unicode_eval> is not enabled by
+default. In our opinion, C<use feature> had one main effect - newer perl
+versions don't value backwards compatibility and the ability to write
+modules for multiple perl versions much, after all, you can use feature.
+
+C<unicode_eval> doesn't add a new feature, it breaks an existing function.
+
+=item no warnings, but a lot of new errors
+
+Ah, the dreaded warnings. Even worse, the horribly dreaded C<-w>
+switch: Even though we don't care if other people use warnings (and
+certainly there are useful ones), a lot of warnings simply go against the
+spirit of Perl.
+
+Most prominently, the warnings related to C<undef>. There is nothing wrong
+with C<undef>: it has well-defined semantics, it is useful, and spitting
+out warnings you never asked for is just evil.
+
+The result was that every one of our modules did C<no warnings> in the
+past, to avoid somebody accidentally using and forcing his bad standards
+on our code. Of course, this switched off all warnings, even the useful
+ones. Not a good situation. Really, the C<-w> switch should only enable
+warnings for the main program only.
+
+Funnily enough, L<perllexwarn> explicitly mentions C<-w> (and not in a
+favourable way, calling it outright "wrong"), but standard utilities, such
+as L<prove>, or MakeMaker when running C<make test>, still enable them
+blindly.
+
+For version 2 of common::sense, we finally sat down a few hours and went
+through I<every single warning message>, identifying - according to
+common sense - all the useful ones.
+
+This resulted in the rather impressive list in the SYNOPSIS. When we
+weren't sure, we didn't include the warning, so the list might grow in
+the future (we might have made a mistake, too, so the list might shrink
+as well).
+
+Note the presence of C<FATAL> in the list: we do not think that the
+conditions caught by these warnings are worthy of a warning, we I<insist>
+that they are worthy of I<stopping> your program, I<instantly>. They are
+I<bugs>!
+
+Therefore we consider C<common::sense> to be much stricter than C<use
+warnings>, which is good if you are into strict things (we are not,
+actually, but these things tend to be subjective).
+
+After deciding on the list, we ran the module against all of our code that
+uses C<common::sense> (that is almost all of our code), and found only one
+occurrence where one of them caused a problem: one of elmex's (unreleased)
+modules contained:
+
+   $fmt =~ s/([^\s\[]*)\[( [^\]]* )\]/\x0$1\x1$2\x0/xgo;
+
+We quickly agreed that indeed the code should be changed, even though it
+happened to do the right thing when the warning was switched off.
+
+
+=item much reduced typing
+
+Especially with version 2.0 of common::sense, the amount of boilerplate
+code you need to add to get I<this> policy is daunting. Nobody would write
+this out in throwaway scripts, commandline hacks or in quick internal-use
+scripts.
+
+By using common::sense you get a defined set of policies (ours, but maybe
+yours, too, if you accept them), and they are easy to apply to your
+scripts: typing C<use common::sense;> is even shorter than C<use warnings;
+use strict; use feature ...>.
+
+And you can immediately use the features of your installed perl, which
+is more difficult in code you release, but not usually an issue for
+internal-use code (downgrades of your production perl should be rare,
+right?).
+
+
+=item mucho reduced memory usage
+
+Just using all those pragmas mentioned in the SYNOPSIS together wastes
+<blink>I<< B<776> kilobytes >></blink> of precious memory in my perl, for
+I<every single perl process using our code>, which on our machines, is a
+lot. In comparison, this module only uses I<< B<four> >> kilobytes (I even
+had to write it out so it looks like more) of memory on the same platform.
+
+The money/time/effort/electricity invested in these gigabytes (probably
+petabytes globally!) of wasted memory could easily save 42 trees, and a
+kitten!
+
+Unfortunately, until everybody applies more common sense, there will still
+often be modules that pull in the monster pragmas. But one can hope...
+
+=back
+
+=head1 THERE IS NO 'no common::sense'!!!! !!!! !!
+
+This module doesn't offer an unimport. First of all, it wastes even more
+memory, second, and more importantly, who with even a bit of common sense
+would want no common sense?
+
+=head1 STABILITY AND FUTURE VERSIONS
+
+Future versions might change just about everything in this module. We
+might test our modules and upload new ones working with newer versions of
+this module, and leave you standing in the rain because we didn't tell
+you. In fact, we did so when switching from 1.0 to 2.0, which enabled gobs
+of warnings, and made them FATAL on top.
+
+Maybe we will load some nifty modules that try to emulate C<say> or so
+with perls older than 5.10 (this module, of course, should work with older
+perl versions - supporting 5.8 for example is just common sense at this
+time. Maybe not in the future, but of course you can trust our common
+sense to be consistent with, uhm, our opinion).
+
+=head1 WHAT OTHER PEOPLE HAD TO SAY ABOUT THIS MODULE
+
+apeiron
+
+   "... wow"
+   "I hope common::sense is a joke."
+
+crab
+
+   "i wonder how it would be if joerg schilling wrote perl modules."
+
+Adam Kennedy
+
+   "Very interesting, efficient, and potentially something I'd use all the time."
+   [...]
+   "So no common::sense for me, alas."
+
+H.Merijn Brand
+
+   "Just one more reason to drop JSON::XS from my distribution list"
+
+Pista Palo
+
+   "Something in short supply these days..."
+
+Steffen Schwigon
+
+   "This module is quite for sure *not* just a repetition of all the other
+   'use strict, use warnings'-approaches, and it's also not the opposite.
+   [...] And for its chosen middle-way it's also not the worst name ever.
+   And everything is documented."
+
+BKB
+
+   "[Deleted - thanks to Steffen Schwigon for pointing out this review was
+   in error.]"
+
+Somni
+
+   "the arrogance of the guy"
+   "I swear he tacked somenoe else's name onto the module
+   just so he could use the royal 'we' in the documentation"
+
+Anonymous Monk
+
+   "You just gotta love this thing, its got META.json!!!"
+
+dngor
+
+   "Heh.  '"<elmex at ta-sa.org>"'  The quotes are semantic
+   distancing from that e-mail address."
+
+Jerad Pierce
+
+   "Awful name (not a proper pragma), and the SYNOPSIS doesn't tell you
+   anything either. Nor is it clear what features have to do with "common
+   sense" or discipline."
+
+acme
+
+   "THERE IS NO 'no common::sense'!!!! !!!! !!"
+
+apeiron (meta-comment about us commenting^Wquoting his comment)
+
+   "How about quoting this: get a clue, you fucktarded amoeba."
+
+quanth
+
+   "common sense is beautiful, json::xs is fast, Anyevent, EV are fast and
+   furious. I love mlehmannware ;)"
+
+apeiron
+
+   "... it's mlehmann's view of what common sense is. His view of common
+   sense is certainly uncommon, insofar as anyone with a clue disagrees
+   with him."
+
+apeiron (another meta-comment)
+
+   "apeiron wonders if his little informant is here to steal more quotes"
+
+ew73
+
+   "... I never got past the SYNOPSIS before calling it shit."
+   [...]
+   How come no one ever quotes me. :("
+
+chip (not willing to explain his cryptic questions about links in Changes files)
+
+   "I'm willing to ask the question I've asked. I'm not willing to go
+   through the whole dance you apparently have choreographed. Either
+   answer the completely obvious question, or tell me to fuck off again."
+
+=head1 FREQUENTLY ASKED QUESTIONS
+
+Or frequently-come-up confusions.
+
+=over 4
+
+=item Is this module meant to be serious?
+
+Yes, we would have put it under the C<Acme::> namespace otherwise.
+
+=item But the manpage is written in a funny/stupid/... way?
+
+This was meant to make it clear that our common sense is a subjective
+thing and other people can use their own notions, taking the steam out
+of anybody who might be offended (as some people are always offended no
+matter what you do).
+
+This was a failure.
+
+But we hope the manpage still is somewhat entertaining even though it
+explains boring rationale.
+
+=item Why do you impose your conventions on my code?
+
+For some reason people keep thinking that C<common::sense> imposes
+process-wide limits, even though the SYNOPSIS makes it clear that it works
+like other similar modules - i.e. only within the scope that C<use>s them.
+
+So, no, we don't - nobody is forced to use this module, and using a module
+that relies on common::sense does not impose anything on you.
+
+=item Why do you think only your notion of common::sense is valid?
+
+Well, we don't, and have clearly written this in the documentation to
+every single release. We were just faster than anybody else w.r.t. to
+grabbing the namespace.
+
+=item But everybody knows that you have to use strict and use warnings,
+why do you disable them?
+
+Well, we don't do this either - we selectively disagree with the
+usefulness of some warnings over others. This module is aimed at
+experienced Perl programmers, not people migrating from other languages
+who might be surprised about stuff such as C<undef>. On the other hand,
+this does not exclude the usefulness of this module for total newbies, due
+to its strictness in enforcing policy, while at the same time not limiting
+the expressive power of perl.
+
+This module is considerably I<more> strict than the canonical C<use
+strict; use warnings>, as it makes all its warnings fatal in nature, so
+you can not get away with as many things as with the canonical approach.
+
+This was not implemented in version 1.0 because of the daunting number
+of warning categories and the difficulty in getting exactly the set of
+warnings you wish (i.e. look at the SYNOPSIS in how complicated it is to
+get a specific set of warnings - it is not reasonable to put this into
+every module, the maintenance effort would be enormous).
+
+=item But many modules C<use strict> or C<use warnings>, so the memory
+savings do not apply?
+
+I suddenly feel sad...
+
+But yes, that's true. Fortunately C<common::sense> still uses only a
+miniscule amount of RAM.
+
+=item But it adds another dependency to your modules!
+
+It's a fact, yeah. But it's trivial to install, most popular modules have
+many more dependencies. And we consider dependencies a good thing - it
+leads to better APIs, more thought about interworking of modules and so
+on.
+
+=item Why do you use JSON and not YAML for your META.yml?
+
+This is not true - YAML supports a large subset of JSON, and this subset
+is what META.yml is written in, so it would be correct to say "the
+META.yml is written in a common subset of YAML and JSON".
+
+The META.yml follows the YAML, JSON and META.yml specifications, and is
+correctly parsed by CPAN, so if you have trouble with it, the problem is
+likely on your side.
+
+=item But! But!
+
+Yeah, we know.
+
+=back
+
+=head1 AUTHOR
+
+ Marc Lehmann <schmorp@schmorp.de>
+ http://home.schmorp.de/
+
+ Robin Redeker, "<elmex at ta-sa.org>".
+
+=cut
+