common-sense/sense.pm.PL

#! perl-000

open STDOUT, ">$ARGV[0]~"
   or die "$ARGV[0]~: $!";

our $WARN;
our $H;
our %H;

BEGIN {
   $H    = $^H;
   $WARN = ${^WARNING_BITS};
}

use utf8;
use strict qw(subs vars);

BEGIN {
   if ($] >= 5.010) {
      require feature;
      feature->import (qw(say state switch));
   }
   if ($] >= 5.012) {
      feature->import (qw(unicode_strings));
   }
   if ($] >= 5.016) {
      feature->import (qw(current_sub fc evalbytes));
      feature->unimport (qw(array_base));
   }
}

no warnings;
use warnings qw(FATAL closed threads internal debugging pack malloc portable prototype
                inplace io pipe unpack deprecated glob digit printf
                layer reserved taint closure semicolon);
no warnings qw(exec newline unopened);

BEGIN {
   $H    = $^H              & ~$H;
   $WARN = ${^WARNING_BITS} & ~$WARN;
   %H    = %^H;
}

while (<DATA>) {
   if (/^IMPORT/) {
      print "   # use warnings\n";
      printf "   \${^WARNING_BITS} ^= \${^WARNING_BITS} ^ \"%s\";\n",
             join "", map "\\x$_", unpack "(H2)*", $WARN;
      print "   # use strict, use utf8; use feature;\n";
      printf "   \$^H |= 0x%x;\n", $H;

      if (my @features = grep /^feature_/, keys %H) {
         print "   \@^H{qw(@features)} = (1) x ", (scalar @features), ";\n";
      }
   } else {
      print;
   }
}

close STDOUT;
rename "$ARGV[0]~", $ARGV[0];

__DATA__

=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
   #                 portable prototype inplace io pipe unpack malloc
   #                 deprecated 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...

=cut

package common::sense;

our $VERSION = '3.6';

# overload should be included

sub import {
   local $^W; # work around perl 5.16 spewing out warnings for next statement
IMPORT
}

1;

=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

Revision:	1.12
Committed:	Thu Jun 27 11:43:43 2013 UTC (10 years, 10 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.11:	+5 -5 lines
Log Message:	typos David Steinbrunner
#	User	Rev	Content
1	root	1.7	#! perl-000
2	root	1.1
3			open STDOUT, ">$ARGV[0]~"
4			or die "$ARGV[0]~: $!";
5
6			our $WARN;
7			our $H;
8	root	1.10	our %H;
9	root	1.1
10			BEGIN {
11			$H = $^H;
12			$WARN = ${^WARNING_BITS};
13			}
14
15			use utf8;
16			use strict qw(subs vars);
17
18	root	1.10	BEGIN {
19			if ($] >= 5.010) {
20			require feature;
21			feature->import (qw(say state switch));
22			}
23			if ($] >= 5.012) {
24			feature->import (qw(unicode_strings));
25			}
26			if ($] >= 5.016) {
27			feature->import (qw(current_sub fc evalbytes));
28			feature->unimport (qw(array_base));
29			}
30			}
31
32	root	1.1	no warnings;
33	root	1.4	use warnings qw(FATAL closed threads internal debugging pack malloc portable prototype
34	root	1.7	inplace io pipe unpack deprecated glob digit printf
35	root	1.2	layer reserved taint closure semicolon);
36	root	1.1	no warnings qw(exec newline unopened);
37
38			BEGIN {
39			$H = $^H & ~$H;
40			$WARN = ${^WARNING_BITS} & ~$WARN;
41	root	1.10	%H = %^H;
42	root	1.1	}
43
44			while (<DATA>) {
45			if (/^IMPORT/) {
46			print " # use warnings\n";
47			printf " \${^WARNING_BITS} ^= \${^WARNING_BITS} ^ \"%s\";\n",
48			join "", map "\\x$_", unpack "(H2)*", $WARN;
49	root	1.10	print " # use strict, use utf8; use feature;\n";
50	root	1.1	printf " \$^H \|= 0x%x;\n", $H;
51	root	1.10
52			if (my @features = grep /^feature_/, keys %H) {
53			print " \@^H{qw(@features)} = (1) x ", (scalar @features), ";\n";
54			}
55	root	1.1	} else {
56			print;
57			}
58			}
59
60			close STDOUT;
61			rename "$ARGV[0]~", $ARGV[0];
62
63			__DATA__
64
65			=head1 NAME
66
67			common::sense - save a tree AND a kitten, use common::sense!
68
69			=head1 SYNOPSIS
70
71	root	1.10	use common::sense;
72	root	1.1
73	root	1.10	# Supposed to be mostly the same, with much lower memory usage, as:
74
75			# use utf8;
76			# use strict qw(vars subs);
77			# use feature qw(say state switch);
78			# use feature qw(unicode_strings unicode_eval current_sub fc evalbytes);
79			# no feature qw(array_base);
80			# no warnings;
81			# use warnings qw(FATAL closed threads internal debugging pack
82			# portable prototype inplace io pipe unpack malloc
83			# deprecated glob digit printf layer
84			# reserved taint closure semicolon);
85			# no warnings qw(exec newline unopened);
86	root	1.5
87	root	1.1	=head1 DESCRIPTION
88
89	root	1.5	“Nothing is more fairly distributed than common sense: no one thinks
90			he needs more of it than he already has.”
91
92			– René Descartes
93
94	root	1.1	This module implements some sane defaults for Perl programs, as defined by
95			two typical (or not so typical - use your common sense) specimens of Perl
96			coders. In fact, after working out details on which warnings and strict
97			modes to enable and make fatal, we found that we (and our code written so
98			far, and others) fully agree on every option, even though we never used
99			warnings before, so it seems this module indeed reflects a "common" sense
100			among some long-time Perl coders.
101
102			The basic philosophy behind the choices made in common::sense can be
103			summarised as: "enforcing strict policies to catch as many bugs as
104			possible, while at the same time, not limiting the expressive power
105			available to the programmer".
106
107			Two typical examples of how this philosophy is applied in practise is the
108			handling of uninitialised and malloc warnings:
109
110			=over 4
111
112			=item I<uninitialised>
113
114			C<undef> is a well-defined feature of perl, and enabling warnings for
115			using it rarely catches any bugs, but considerably limits you in what you
116			can do, so uninitialised warnings are disabled.
117
118			=item I<malloc>
119
120			Freeing something twice on the C level is a serious bug, usually causing
121			memory corruption. It often leads to side effects much later in the
122			program and there are no advantages to not reporting this, so malloc
123			warnings are fatal by default.
124
125			=back
126
127	root	1.7	Unfortunately, there is no fine-grained warning control in perl, so often
128			whole groups of useful warnings had to be excluded because of a single
129			useless warning (for example, perl puts an arbitrary limit on the length
130			of text you can match with some regexes before emitting a warning, making
131			the whole C<regexp> category useless).
132
133	root	1.1	What follows is a more thorough discussion of what this module does,
134			and why it does it, and what the advantages (and disadvantages) of this
135			approach are.
136
137			=head1 RATIONALE
138
139			=over 4
140
141			=item use utf8
142
143			While it's not common sense to write your programs in UTF-8, it's quickly
144			becoming the most common encoding, is the designated future default
145			encoding for perl sources, and the most convenient encoding available
146			(you can do really nice quoting tricks...). Experience has shown that our
147			programs were either all pure ascii or utf-8, both of which will stay the
148			same.
149
150			There are few drawbacks to enabling UTF-8 source code by default (mainly
151			some speed hits due to bugs in older versions of perl), so this module
152			enables UTF-8 source code encoding by default.
153
154
155			=item use strict qw(subs vars)
156
157			Using C<use strict> is definitely common sense, but C<use strict
158			'refs'> definitely overshoots its usefulness. After almost two
159			decades of Perl hacking, we decided that it does more harm than being
160			useful. Specifically, constructs like these:
161
162			@{ $var->[0] }
163
164			Must be written like this (or similarly), when C<use strict 'refs'> is in
165			scope, and C<$var> can legally be C<undef>:
166
167			@{ $var->[0] \|\| [] }
168
169			This is annoying, and doesn't shield against obvious mistakes such as
170			using C<"">, so one would even have to write (at least for the time
171			being):
172
173			@{ defined $var->[0] ? $var->[0] : [] }
174
175			... which nobody with a bit of common sense would consider
176			writing: clear code is clearly something else.
177
178			Curiously enough, sometimes perl is not so strict, as this works even with
179			C<use strict> in scope:
180
181			for (@{ $var->[0] }) { ...
182
183			If that isn't hypocrisy! And all that from a mere program!
184
185
186	root	1.10	=item use feature qw(say state given ...)
187	root	1.1
188			We found it annoying that we always have to enable extra features. If
189			something breaks because it didn't anticipate future changes, so be
190			it. 5.10 broke almost all our XS modules and nobody cared either (or at
191			least I know of nobody who really complained about gratuitous changes -
192			as opposed to bugs).
193
194			Few modules that are not actively maintained work with newer versions of
195			Perl, regardless of use feature or not, so a new major perl release means
196			changes to many modules - new keywords are just the tip of the iceberg.
197
198			If your code isn't alive, it's dead, Jim - be an active maintainer.
199
200			But nobody forces you to use those extra features in modules meant for
201			older versions of perl - common::sense of course works there as well.
202			There is also an important other mode where having additional features by
203			default is useful: commandline hacks and internal use scripts: See "much
204			reduced typing", below.
205
206	root	1.10	There is one notable exception: C<unicode_eval> is not enabled by
207			default. In our opinion, C<use feature> had one main effect - newer perl
208			versions don't value backwards compatibility and the ability to write
209			modules for multiple perl versions much, after all, you can use feature.
210
211			C<unicode_eval> doesn't add a new feature, it breaks an existing function.
212	root	1.1
213			=item no warnings, but a lot of new errors
214
215			Ah, the dreaded warnings. Even worse, the horribly dreaded C<-w>
216			switch: Even though we don't care if other people use warnings (and
217			certainly there are useful ones), a lot of warnings simply go against the
218			spirit of Perl.
219
220			Most prominently, the warnings related to C<undef>. There is nothing wrong
221			with C<undef>: it has well-defined semantics, it is useful, and spitting
222			out warnings you never asked for is just evil.
223
224			The result was that every one of our modules did C<no warnings> in the
225			past, to avoid somebody accidentally using and forcing his bad standards
226			on our code. Of course, this switched off all warnings, even the useful
227			ones. Not a good situation. Really, the C<-w> switch should only enable
228			warnings for the main program only.
229
230			Funnily enough, L<perllexwarn> explicitly mentions C<-w> (and not in a
231			favourable way, calling it outright "wrong"), but standard utilities, such
232			as L<prove>, or MakeMaker when running C<make test>, still enable them
233			blindly.
234
235			For version 2 of common::sense, we finally sat down a few hours and went
236	root	1.12	through I<every single warning message>, identifying - according to
237	root	1.1	common sense - all the useful ones.
238
239			This resulted in the rather impressive list in the SYNOPSIS. When we
240			weren't sure, we didn't include the warning, so the list might grow in
241			the future (we might have made a mistake, too, so the list might shrink
242			as well).
243
244			Note the presence of C<FATAL> in the list: we do not think that the
245			conditions caught by these warnings are worthy of a warning, we I<insist>
246			that they are worthy of I<stopping> your program, I<instantly>. They are
247			I<bugs>!
248
249			Therefore we consider C<common::sense> to be much stricter than C<use
250			warnings>, which is good if you are into strict things (we are not,
251			actually, but these things tend to be subjective).
252
253			After deciding on the list, we ran the module against all of our code that
254			uses C<common::sense> (that is almost all of our code), and found only one
255	root	1.12	occurrence where one of them caused a problem: one of elmex's (unreleased)
256	root	1.1	modules contained:
257
258			$fmt =~ s/([^\s\[])\[( [^\]] )\]/\x0$1\x1$2\x0/xgo;
259
260			We quickly agreed that indeed the code should be changed, even though it
261			happened to do the right thing when the warning was switched off.
262
263
264			=item much reduced typing
265
266			Especially with version 2.0 of common::sense, the amount of boilerplate
267	root	1.12	code you need to add to get I<this> policy is daunting. Nobody would write
268	root	1.1	this out in throwaway scripts, commandline hacks or in quick internal-use
269			scripts.
270
271			By using common::sense you get a defined set of policies (ours, but maybe
272			yours, too, if you accept them), and they are easy to apply to your
273			scripts: typing C<use common::sense;> is even shorter than C<use warnings;
274			use strict; use feature ...>.
275
276			And you can immediately use the features of your installed perl, which
277			is more difficult in code you release, but not usually an issue for
278			internal-use code (downgrades of your production perl should be rare,
279			right?).
280
281
282			=item mucho reduced memory usage
283
284			Just using all those pragmas mentioned in the SYNOPSIS together wastes
285			<blink>I<< B<776> kilobytes >></blink> of precious memory in my perl, for
286			I<every single perl process using our code>, which on our machines, is a
287			lot. In comparison, this module only uses I<< B<four> >> kilobytes (I even
288			had to write it out so it looks like more) of memory on the same platform.
289
290			The money/time/effort/electricity invested in these gigabytes (probably
291			petabytes globally!) of wasted memory could easily save 42 trees, and a
292			kitten!
293
294	root	1.12	Unfortunately, until everybody applies more common sense, there will still
295	root	1.1	often be modules that pull in the monster pragmas. But one can hope...
296
297			=cut
298
299			package common::sense;
300
301	root	1.11	our $VERSION = '3.6';
302	root	1.1
303			# overload should be included
304
305			sub import {
306	root	1.10	local $^W; # work around perl 5.16 spewing out warnings for next statement
307	root	1.1	IMPORT
308			}
309
310			1;
311
312			=back
313
314			=head1 THERE IS NO 'no common::sense'!!!! !!!! !!
315
316			This module doesn't offer an unimport. First of all, it wastes even more
317			memory, second, and more importantly, who with even a bit of common sense
318			would want no common sense?
319
320			=head1 STABILITY AND FUTURE VERSIONS
321
322			Future versions might change just about everything in this module. We
323			might test our modules and upload new ones working with newer versions of
324			this module, and leave you standing in the rain because we didn't tell
325			you. In fact, we did so when switching from 1.0 to 2.0, which enabled gobs
326			of warnings, and made them FATAL on top.
327
328			Maybe we will load some nifty modules that try to emulate C<say> or so
329			with perls older than 5.10 (this module, of course, should work with older
330			perl versions - supporting 5.8 for example is just common sense at this
331			time. Maybe not in the future, but of course you can trust our common
332			sense to be consistent with, uhm, our opinion).
333
334			=head1 WHAT OTHER PEOPLE HAD TO SAY ABOUT THIS MODULE
335
336			apeiron
337
338			"... wow"
339			"I hope common::sense is a joke."
340
341			crab
342
343			"i wonder how it would be if joerg schilling wrote perl modules."
344
345			Adam Kennedy
346
347			"Very interesting, efficient, and potentially something I'd use all the time."
348			[...]
349			"So no common::sense for me, alas."
350
351			H.Merijn Brand
352
353			"Just one more reason to drop JSON::XS from my distribution list"
354
355			Pista Palo
356
357			"Something in short supply these days..."
358
359			Steffen Schwigon
360
361			"This module is quite for sure not just a repetition of all the other
362			'use strict, use warnings'-approaches, and it's also not the opposite.
363			[...] And for its chosen middle-way it's also not the worst name ever.
364			And everything is documented."
365
366			BKB
367
368			"[Deleted - thanks to Steffen Schwigon for pointing out this review was
369			in error.]"
370
371			Somni
372
373			"the arrogance of the guy"
374			"I swear he tacked somenoe else's name onto the module
375			just so he could use the royal 'we' in the documentation"
376
377			Anonymous Monk
378
379			"You just gotta love this thing, its got META.json!!!"
380
381			dngor
382
383			"Heh. '"<elmex at ta-sa.org>"' The quotes are semantic
384			distancing from that e-mail address."
385
386			Jerad Pierce
387
388			"Awful name (not a proper pragma), and the SYNOPSIS doesn't tell you
389			anything either. Nor is it clear what features have to do with "common
390			sense" or discipline."
391
392			acme
393
394			"THERE IS NO 'no common::sense'!!!! !!!! !!"
395
396			apeiron (meta-comment about us commenting^Wquoting his comment)
397
398			"How about quoting this: get a clue, you fucktarded amoeba."
399
400			quanth
401
402			"common sense is beautiful, json::xs is fast, Anyevent, EV are fast and
403			furious. I love mlehmannware ;)"
404
405			apeiron
406
407			"... it's mlehmann's view of what common sense is. His view of common
408			sense is certainly uncommon, insofar as anyone with a clue disagrees
409			with him."
410
411			apeiron (another meta-comment)
412
413			"apeiron wonders if his little informant is here to steal more quotes"
414
415			ew73
416
417			"... I never got past the SYNOPSIS before calling it shit."
418			[...]
419			How come no one ever quotes me. :("
420
421	root	1.8	chip (not willing to explain his cryptic questions about links in Changes files)
422
423			"I'm willing to ask the question I've asked. I'm not willing to go
424			through the whole dance you apparently have choreographed. Either
425			answer the completely obvious question, or tell me to fuck off again."
426
427	root	1.1	=head1 FREQUENTLY ASKED QUESTIONS
428
429			Or frequently-come-up confusions.
430
431			=over 4
432
433			=item Is this module meant to be serious?
434
435			Yes, we would have put it under the C<Acme::> namespace otherwise.
436
437			=item But the manpage is written in a funny/stupid/... way?
438
439			This was meant to make it clear that our common sense is a subjective
440			thing and other people can use their own notions, taking the steam out
441			of anybody who might be offended (as some people are always offended no
442			matter what you do).
443
444			This was a failure.
445
446			But we hope the manpage still is somewhat entertaining even though it
447			explains boring rationale.
448
449			=item Why do you impose your conventions on my code?
450
451			For some reason people keep thinking that C<common::sense> imposes
452			process-wide limits, even though the SYNOPSIS makes it clear that it works
453			like other similar modules - i.e. only within the scope that C<use>s them.
454
455			So, no, we don't - nobody is forced to use this module, and using a module
456			that relies on common::sense does not impose anything on you.
457
458			=item Why do you think only your notion of common::sense is valid?
459
460			Well, we don't, and have clearly written this in the documentation to
461			every single release. We were just faster than anybody else w.r.t. to
462			grabbing the namespace.
463
464			=item But everybody knows that you have to use strict and use warnings,
465			why do you disable them?
466
467			Well, we don't do this either - we selectively disagree with the
468			usefulness of some warnings over others. This module is aimed at
469			experienced Perl programmers, not people migrating from other languages
470			who might be surprised about stuff such as C<undef>. On the other hand,
471			this does not exclude the usefulness of this module for total newbies, due
472			to its strictness in enforcing policy, while at the same time not limiting
473	root	1.7	the expressive power of perl.
474	root	1.1
475			This module is considerably I<more> strict than the canonical C<use
476			strict; use warnings>, as it makes all its warnings fatal in nature, so
477			you can not get away with as many things as with the canonical approach.
478
479			This was not implemented in version 1.0 because of the daunting number
480			of warning categories and the difficulty in getting exactly the set of
481			warnings you wish (i.e. look at the SYNOPSIS in how complicated it is to
482			get a specific set of warnings - it is not reasonable to put this into
483	root	1.12	every module, the maintenance effort would be enormous).
484	root	1.1
485			=item But many modules C<use strict> or C<use warnings>, so the memory
486			savings do not apply?
487
488			I suddenly feel sad...
489
490			But yes, that's true. Fortunately C<common::sense> still uses only a
491			miniscule amount of RAM.
492
493			=item But it adds another dependency to your modules!
494
495			It's a fact, yeah. But it's trivial to install, most popular modules have
496			many more dependencies and we consider dependencies a good thing - it
497			leads to better APIs, more thought about interworking of modules and so
498			on.
499
500			=item Why do you use JSON and not YAML for your META.yml?
501
502			This is not true - YAML supports a large subset of JSON, and this subset
503			is what META.yml is written in, so it would be correct to say "the
504			META.yml is written in a common subset of YAML and JSON".
505
506			The META.yml follows the YAML, JSON and META.yml specifications, and is
507			correctly parsed by CPAN, so if you have trouble with it, the problem is
508			likely on your side.
509
510			=item But! But!
511
512			Yeah, we know.
513
514			=back
515
516			=head1 AUTHOR
517
518			Marc Lehmann <schmorp@schmorp.de>
519			http://home.schmorp.de/
520
521			Robin Redeker, "<elmex at ta-sa.org>".
522
523			=cut
524