common-sense/sense.pm

=head1 NAME

common::sense - save a tree AND a kitten, use common::sense!

=head1 SYNOPSIS

 use common::sense;

 # roughly the same as, with much lower memory usage:
 #
 # use strict qw(vars subs);
 # use feature qw(say state switch);
 # no warnings;

=head1 DESCRIPTION

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.

=over 4

=item no warnings

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.

So every module needs C<no warnings> to avoid somebody accidentally using
C<-w> and forcing his bad standards on our code. No will do. Really, the
C<-w> switch should only enable wanrings for the main program.

Funnily enough, L<perllexwarn> explicitly mentions C<-w> (and not in a
favourable way), but standard utilities, such as L<prove>, or MakeMaker
when running C<make test> enable them blindly.

=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.

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 hipocrasy! 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
leats I know of nobody who really complained about gratitious 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.

=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 everybods 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 = '1.0';

# no warnings;
# use warnings qw(FATAL closed threads internal debugging pack substr malloc unopened portable prototype
#                 inplace io pipe unpack regexp deprecated exiting redefine glob digit printf
#                 utf8 layer reserved parenthesis taint closure);
# BEGIN { warn join "", map "\\x$_", unpack "(H2)*", ${^WARNING_BITS} };

# overload should be included

sub import {
   # verified with perl 5.8.0, 5.10.0
   ${^WARNING_BITS} = "\xfc\xff\xff\x00\xcf\xf3\xcf\xc0\xf3\xcc\x33\x03";

   # use strict vars subs
   $^H |= 0x00000600;

   # use feature
   $^H{feature_switch} =
   $^H{feature_say}    =
   $^H{feature_state}  = 1;
}

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.

Most likely, we will pick a few useful warnings, instead of just disabling
all of them. And 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."

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"

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)

   How about quoting this: get a clue, you fucktarded amoeba.

=head1 AUTHOR

 Marc Lehmann <schmorp@schmorp.de>
 http://home.schmorp.de/

 Robin Redeker, "<elmex at ta-sa.org>".

=cut

Revision:	1.13
Committed:	Tue Sep 1 13:42:29 2009 UTC (14 years, 10 months ago) by root
Branch:	MAIN
Changes since 1.12:	+10 -2 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	=head1 NAME
2
3			common::sense - save a tree AND a kitten, use common::sense!
4
5			=head1 SYNOPSIS
6
7			use common::sense;
8
9			# roughly the same as, with much lower memory usage:
10			#
11			# use strict qw(vars subs);
12			# use feature qw(say state switch);
13			# no warnings;
14
15			=head1 DESCRIPTION
16
17			This module implements some sane defaults for Perl programs, as defined by
18			two typical (or not so typical - use your common sense) specimens of
19			Perl coders.
20
21			=over 4
22
23	root	1.4	=item no warnings
24
25	root	1.11	Ah, the dreaded warnings. Even worse, the horribly dreaded C<-w>
26			switch: Even though we don't care if other people use warnings (and
27			certainly there are useful ones), a lot of warnings simply go against the
28			spirit of Perl.
29
30			Most prominently, the warnings related to C<undef>. There is nothing wrong
31			with C<undef>: it has well-defined semantics, it is useful, and spitting
32			out warnings you never asked for is just evil.
33	root	1.4
34			So every module needs C<no warnings> to avoid somebody accidentally using
35	root	1.11	C<-w> and forcing his bad standards on our code. No will do. Really, the
36			C<-w> switch should only enable wanrings for the main program.
37	root	1.4
38			Funnily enough, L<perllexwarn> explicitly mentions C<-w> (and not in a
39			favourable way), but standard utilities, such as L<prove>, or MakeMaker
40			when running C<make test> enable them blindly.
41
42	root	1.1	=item use strict qw(subs vars)
43
44			Using C<use strict> is definitely common sense, but C<use strict
45	root	1.11	'refs'> definitely overshoots its usefulness. After almost two
46	root	1.1	decades of Perl hacking, we decided that it does more harm than being
47			useful. Specifically, constructs like these:
48
49			@{ $var->[0] }
50
51	root	1.4	Must be written like this (or similarly), when C<use strict 'refs'> is in
52			scope, and C<$var> can legally be C<undef>:
53	root	1.1
54			@{ $var->[0] \|\| [] }
55
56			This is annoying, and doesn't shield against obvious mistakes such as
57	root	1.11	using C<"">, so one would even have to write (at least for the time
58			being):
59	root	1.1
60			@{ defined $var->[0] ? $var->[0] : [] }
61
62			... which nobody with a bit of common sense would consider
63	root	1.11	writing.
64
65			Curiously enough, sometimes perl is not so strict, as this works even with
66			C<use strict> in scope:
67	root	1.1
68			for (@{ $var->[0] }) { ...
69
70	root	1.11	If that isn't hipocrasy! And all that from a mere program!
71	root	1.1
72			=item use feature qw(say state given)
73
74			We found it annoying that we always have to enable extra features. If
75			something breaks because it didn't anticipate future changes, so be
76	root	1.11	it. 5.10 broke almost all our XS modules and nobody cared either (or at
77			leats I know of nobody who really complained about gratitious changes - as
78			opposed to bugs).
79
80			Few modules that are not actively maintained work with newer versions of
81			Perl, regardless of use feature or not, so a new major perl release means
82			changes to many modules - new keywords are just the tip of the iceberg.
83
84			If your code isn't alive, it's dead, jim - be an active maintainer.
85
86			=item mucho reduced memory usage
87
88			Just using all those pragmas mentioned in the SYNOPSIS together wastes
89			<blink>I<< B<776> kilobytes >></blink> of precious memory in my perl, for
90			I<every single perl process using our code>, which on our machines, is a
91			lot. In comparison, this module only uses I<< B<four> >> kilobytes (I even
92			had to write it out so it looks like more) of memory on the same platform.
93	root	1.1
94			The money/time/effort/electricity invested in these gigabytes (probably
95			petabytes globally!) of wasted memory could easily save 42 trees, and a
96			kitten!
97
98	root	1.11	Unfortunately, until everybods applies more common sense, there will still
99			often be modules that pull in the monster pragmas. But one can hope...
100
101	root	1.1	=cut
102
103	root	1.2	package common::sense;
104	root	1.1
105	root	1.11	our $VERSION = '1.0';
106	root	1.1
107	root	1.13	# no warnings;
108			# use warnings qw(FATAL closed threads internal debugging pack substr malloc unopened portable prototype
109			# inplace io pipe unpack regexp deprecated exiting redefine glob digit printf
110			# utf8 layer reserved parenthesis taint closure);
111			# BEGIN { warn join "", map "\\x$_", unpack "(H2)*", ${^WARNING_BITS} };
112
113			# overload should be included
114
115	root	1.2	sub import {
116	root	1.13	# verified with perl 5.8.0, 5.10.0
117			${^WARNING_BITS} = "\xfc\xff\xff\x00\xcf\xf3\xcf\xc0\xf3\xcc\x33\x03";
118	root	1.3
119			# use strict vars subs
120			$^H \|= 0x00000600;
121
122			# use feature
123			$^H{feature_switch} =
124			$^H{feature_say} =
125			$^H{feature_state} = 1;
126	root	1.1	}
127
128			1;
129
130			=back
131
132	root	1.5	=head1 THERE IS NO 'no common::sense'!!!! !!!! !!
133	root	1.4
134			This module doesn't offer an unimport. First of all, it wastes even more
135			memory, second, and more importantly, who with even a bit of common sense
136			would want no common sense?
137
138	root	1.5	=head1 STABILITY AND FUTURE VERSIONS
139
140			Future versions might change just about everything in this module. We
141			might test our modules and upload new ones working with newer versions of
142			this module, and leave you standing in the rain because we didn't tell
143			you.
144
145			Most likely, we will pick a few useful warnings, instead of just disabling
146			all of them. And maybe we will load some nifty modules that try to emulate
147			C<say> or so with perls older than 5.10 (this module, of course, should
148			work with older perl versions - supporting 5.8 for example is just common
149	root	1.6	sense at this time. Maybe not in the future, but of course you can trust
150	root	1.11	our common sense to be consistent with, uhm, our opinion).
151
152			=head1 WHAT OTHER PEOPLE HAD TO SAY ABOUT THIS MODULE
153
154			apeiron
155
156			"... wow"
157			"I hope common::sense is a joke."
158
159			crab
160	root	1.5
161	root	1.11	"i wonder how it would be if joerg schilling wrote perl modules."
162	root	1.7
163	root	1.11	H.Merijn Brand
164
165			"Just one more reason to drop JSON::XS from my distribution list"
166	root	1.7
167			Pista Palo
168
169			"Something in short supply these days..."
170
171			Steffen Schwigon
172
173			"This module is quite for sure not just a repetition of all the other
174			'use strict, use warnings'-approaches, and it's also not the opposite.
175			[...] And for its chosen middle-way it's also not the worst name ever.
176			And everything is documented."
177
178			BKB
179
180			"[Deleted - thanks to Steffen Schwigon for pointing out this review was
181			in error.]"
182
183			Somni
184
185			"the arrogance of the guy"
186			"I swear he tacked somenoe else's name onto the module
187			just so he could use the royal 'we' in the documentation"
188
189			dngor
190
191			"Heh. '"<elmex at ta-sa.org>"' The quotes are semantic
192			distancing from that e-mail address."
193
194			Jerad Pierce
195
196			"Awful name (not a proper pragma), and the SYNOPSIS doesn't tell you
197			anything either. Nor is it clear what features have to do with "common
198			sense" or discipline."
199
200			acme
201
202			"THERE IS NO 'no common::sense'!!!! !!!! !!"
203
204	root	1.12	apeiron (meta-comment)
205
206			How about quoting this: get a clue, you fucktarded amoeba.
207
208	root	1.1	=head1 AUTHOR
209
210			Marc Lehmann <schmorp@schmorp.de>
211			http://home.schmorp.de/
212
213	root	1.4	Robin Redeker, "<elmex at ta-sa.org>".
214
215	root	1.1	=cut
216