[ViewVC] Diff of: cvs/common-sense/sense.pm

Comparing common-sense/sense.pm (file contents):
Revision 1.9 by root, Sat Aug 15 14:12:10 2009 UTC vs.
Revision 1.19 by root, Mon Oct 5 15:02:32 2009 UTC

…		…
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use common::sense;	7	use common::sense;
8		8
9	# roughly the same as, with much lower memory usage:	9	# supposed to be the same, with much lower memory usage, as:
10	#	10	#
11	# use strict qw(vars subs);	11	# use strict qw(vars subs);
12	# use feature qw(say state switch);	12	# use feature qw(say state switch);
13	# no warnings;	13	# no warnings;
		14	# use warnings qw(FATAL closed threads internal debugging pack substr malloc
		15	# unopened portable prototype inplace io pipe unpack regexp
		16	# deprecated exiting glob digit printf utf8 layer
		17	# reserved parenthesis taint closure semicolon);
		18	# no warnings qw(exec newline);
14		19
15	=head1 DESCRIPTION	20	=head1 DESCRIPTION
16		21
17	This module implements some sane defaults for Perl programs, as defined by	22	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	23	two typical (or not so typical - use your common sense) specimens of Perl
19	Perl coders.	24	coders.
20		25
21	=over 4	26	=over 4
22		27
23	=item no warnings
24
25	The dreaded warnings. Even worse, the horribly dreaded C<-w> switch. Even
26	though we don't care if other people use warnings (and certainly there are
27	useful ones), a lot of warnings simply go against the spirit of Perl, most
28	prominently, the warnings related to C<undef>. There is nothing wrong with
29	C<undef>: it has well-defined semantics, it is useful, and spitting out
30	warnings you never asked for is just evil.
31
32	So every module needs C<no warnings> to avoid somebody accidentally using
33	C<-w> and forcing his bad standards on our code. No will do.
34
35	Funnily enough, L<perllexwarn> explicitly mentions C<-w> (and not in a
36	favourable way), but standard utilities, such as L<prove>, or MakeMaker
37	when running C<make test> enable them blindly.
38
39	=item use strict qw(subs vars)	28	=item use strict qw(subs vars)
40		29
41	Using C<use strict> is definitely common sense, but C<use strict	30	Using C<use strict> is definitely common sense, but C<use strict
42	'refs'> definitely overshoots it's usefulness. After almost two	31	'refs'> definitely overshoots its usefulness. After almost two
43	decades of Perl hacking, we decided that it does more harm than being	32	decades of Perl hacking, we decided that it does more harm than being
44	useful. Specifically, constructs like these:	33	useful. Specifically, constructs like these:
45		34
46	@{ $var->[0] }	35	@{ $var->[0] }
47		36
…		…
49	scope, and C<$var> can legally be C<undef>:	38	scope, and C<$var> can legally be C<undef>:
50		39
51	@{ $var->[0] \|\| [] }	40	@{ $var->[0] \|\| [] }
52		41
53	This is annoying, and doesn't shield against obvious mistakes such as	42	This is annoying, and doesn't shield against obvious mistakes such as
54	using C<"">, so one would even have to write:	43	using C<"">, so one would even have to write (at least for the time
		44	being):
55		45
56	@{ defined $var->[0] ? $var->[0] : [] }	46	@{ defined $var->[0] ? $var->[0] : [] }
57		47
58	... which nobody with a bit of common sense would consider	48	... which nobody with a bit of common sense would consider
		49	writing: clear code is clearly something else.
		50
59	writing. Curiously enough, sometimes, perl is not so strict, as this works	51	Curiously enough, sometimes perl is not so strict, as this works even with
60	even with C<use strict> in scope:	52	C<use strict> in scope:
61		53
62	for (@{ $var->[0] }) { ...	54	for (@{ $var->[0] }) { ...
63		55
64	If that isnt hipocrasy! And all that from a mere program!	56	If that isn't hypocrisy! And all that from a mere program!
		57
65		58
66	=item use feature qw(say state given)	59	=item use feature qw(say state given)
67		60
68	We found it annoying that we always have to enable extra features. If	61	We found it annoying that we always have to enable extra features. If
69	something breaks because it didn't anticipate future changes, so be	62	something breaks because it didn't anticipate future changes, so be
70	it. 5.10 broke almost all our XS modules and nobody cared either - and few	63	it. 5.10 broke almost all our XS modules and nobody cared either (or at
		64	least I know of nobody who really complained about gratuitous changes -
		65	as opposed to bugs).
		66
71	modules that are no longer maintained work with newer versions of Perl,	67	Few modules that are not actively maintained work with newer versions of
72	regardless of use feature.	68	Perl, regardless of use feature or not, so a new major perl release means
		69	changes to many modules - new keywords are just the tip of the iceberg.
73		70
74	If your code isn't alive, it's dead, jim.	71	If your code isn't alive, it's dead, Jim - be an active maintainer.
75		72
76	=item much less memory
77		73
78	Just using all those pragmas together wastes <blink>I<< B<776> kilobytes	74	=item no warnings, but a lot of new errors
79	>></blink> of precious memory in my perl, for I<every single perl process	75
80	using our code>, which on our machines, is a lot. In comparison, this	76	Ah, the dreaded warnings. Even worse, the horribly dreaded C<-w>
81	module only uses I<< B<four> >> kilobytes (I even had to write it out so	77	switch: Even though we don't care if other people use warnings (and
		78	certainly there are useful ones), a lot of warnings simply go against the
		79	spirit of Perl.
		80
		81	Most prominently, the warnings related to C<undef>. There is nothing wrong
		82	with C<undef>: it has well-defined semantics, it is useful, and spitting
		83	out warnings you never asked for is just evil.
		84
		85	The result was that every one of our modules did C<no warnings> in the
		86	past, to avoid somebody accidentally using and forcing his bad standards
		87	on our code. Of course, this switched off all warnings, even the useful
		88	ones. Not a good situation. Really, the C<-w> switch should only enable
		89	warnings for the main program only.
		90
		91	Funnily enough, L<perllexwarn> explicitly mentions C<-w> (and not in a
		92	favourable way, calling it outright "wrong"), but standard utilities, such
		93	as L<prove>, or MakeMaker when running C<make test>, still enable them
		94	blindly.
		95
		96	For version 2 of common::sense, we finally sat down a few hours and went
		97	through I<every single warning message>, identifiying - according to
		98	common sense - all the useful ones.
		99
		100	This resulted in the rather impressive list in the SYNOPSIS. When we
		101	weren't sure, we didn't include the warning, so the list might grow in
		102	the future (we might have made a mistake, too, so the list might shrink
		103	as well).
		104
		105	Note the presence of C<FATAL> in the list: we do not think that the
		106	conditions caught by these warnings are worthy of a warning, we I<insist>
		107	that they are worthy of I<stopping> your program, I<instantly>. They are
		108	I<bugs>!
		109
		110	Therefore we consider C<common::sense> to be much stricter than C<use
		111	warnings>, which is good if you are into strict things (we are not,
		112	actually, but these things tend to be subjective).
		113
		114	After deciding on the list, we ran the module against all of our code that
		115	uses C<common::sense> (that is almost all of our code), and found only one
		116	occurence where one of them caused a problem: one of elmex's (unreleased)
		117	modules contained:
		118
		119	$fmt =~ s/([^\s\[])\[( [^\]] )\]/\x0$1\x1$2\x0/xgo;
		120
		121	We quickly agreed that indeed the code should be changed, even though it
		122	happened to do the right thing when the warning was switched off.
		123
		124
		125	=item mucho reduced memory usage
		126
		127	Just using all those pragmas mentioned in the SYNOPSIS together wastes
		128	<blink>I<< B<776> kilobytes >></blink> of precious memory in my perl, for
		129	I<every single perl process using our code>, which on our machines, is a
		130	lot. In comparison, this module only uses I<< B<four> >> kilobytes (I even
82	it looks like more) of memory on the same platform.	131	had to write it out so it looks like more) of memory on the same platform.
83		132
84	The money/time/effort/electricity invested in these gigabytes (probably	133	The money/time/effort/electricity invested in these gigabytes (probably
85	petabytes globally!) of wasted memory could easily save 42 trees, and a	134	petabytes globally!) of wasted memory could easily save 42 trees, and a
86	kitten!	135	kitten!
87		136
		137	Unfortunately, until everybods applies more common sense, there will still
		138	often be modules that pull in the monster pragmas. But one can hope...
		139
88	=cut	140	=cut
89		141
90	package common::sense;	142	package common::sense;
91		143
92	our $VERSION = '0.04';	144	our $VERSION = '2.01';
		145
		146	# paste this into perl to find bitmask
		147
		148	# no warnings;
		149	# use warnings qw(FATAL closed threads internal debugging pack substr malloc unopened portable prototype
		150	# inplace io pipe unpack regexp deprecated exiting glob digit printf
		151	# utf8 layer reserved parenthesis taint closure semicolon);
		152	# no warnings qw(exec newline);
		153	# BEGIN { warn join "", map "\\x$_", unpack "(H2)*", ${^WARNING_BITS}; exit 0 };
		154
		155	# overload should be included
93		156
94	sub import {	157	sub import {
95	# no warnings	158	# verified with perl 5.8.0, 5.10.0
96	${^WARNING_BITS} ^= ${^WARNING_BITS};	159	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\xfc\x3f\xf3\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x03";
97		160
98	# use strict vars subs	161	# use strict vars subs
99	$^H \|= 0x00000600;	162	$^H \|= 0x00000600;
100		163
101	# use feature	164	# use feature
…		…
117	=head1 STABILITY AND FUTURE VERSIONS	180	=head1 STABILITY AND FUTURE VERSIONS
118		181
119	Future versions might change just about everything in this module. We	182	Future versions might change just about everything in this module. We
120	might test our modules and upload new ones working with newer versions of	183	might test our modules and upload new ones working with newer versions of
121	this module, and leave you standing in the rain because we didn't tell	184	this module, and leave you standing in the rain because we didn't tell
122	you.	185	you. In fact, we did so when switching from 1.0 to 2.0, which enabled gobs
		186	of warnings, and made them FATAL on top.
123		187
124	Most likely, we will pick a few useful warnings, instead of just disabling
125	all of them. And maybe we will load some nifty modules that try to emulate	188	Maybe we will load some nifty modules that try to emulate C<say> or so
126	C<say> or so with perls older than 5.10 (this module, of course, should	189	with perls older than 5.10 (this module, of course, should work with older
127	work with older perl versions - supporting 5.8 for example is just common	190	perl versions - supporting 5.8 for example is just common sense at this
128	sense at this time. Maybe not in the future, but of course you can trust	191	time. Maybe not in the future, but of course you can trust our common
129	our common sense).	192	sense to be consistent with, uhm, our opinion).
130		193
131
132	=head1 WHAT OTHER PEOPLE HAVE TO SAY ABOUT THIS MODULE	194	=head1 WHAT OTHER PEOPLE HAD TO SAY ABOUT THIS MODULE
		195
		196	apeiron
		197
		198	"... wow"
		199	"I hope common::sense is a joke."
		200
		201	crab
		202
		203	"i wonder how it would be if joerg schilling wrote perl modules."
		204
		205	Adam Kennedy
		206
		207	"Very interesting, efficient, and potentially something I'd use all the time."
		208	[...]
		209	"So no common::sense for me, alas."
		210
		211	H.Merijn Brand
		212
		213	"Just one more reason to drop JSON::XS from my distribution list"
133		214
134	Pista Palo	215	Pista Palo
135		216
136	"Something in short supply these days..."	217	"Something in short supply these days..."
137		218
…		…
166		247
167	acme	248	acme
168		249
169	"THERE IS NO 'no common::sense'!!!! !!!! !!"	250	"THERE IS NO 'no common::sense'!!!! !!!! !!"
170		251
171	crab	252	apeiron (meta-comment about us commenting^Wquoting his comment)
172		253
173	"i wonder how it would be if joerg schilling wrote perl modules."	254	How about quoting this: get a clue, you fucktarded amoeba.
174		255
175	H.Merijn Brand	256	=head1 FREQUQNTLY ASKED QUESTIONS
176		257
177	"Just one more reason to drop JSON::XS from my distribution list"	258	Or frequently-come-up confusions.
		259
		260	=over 4
		261
		262	=item Is this module meant to be serious?
		263
		264	Yes, we would have put it under the C<Acme::> namespace otherwise.
		265
		266	=item But the manpage is written in a funny/stupid/... way?
		267
		268	This was meant to make it clear that our common sense is a subjective
		269	thing and other people can use their own notions, taking the steam out
		270	of anybody who might be offended (as some people are always offended no
		271	matter what you do).
		272
		273	This was a failure.
		274
		275	But we hope the manpage still is somewhat entertaining even though it
		276	explains boring rationale.
		277
		278	=item Why do you impose your conventions on my code?
		279
		280	For some reason people keep thinking that C<common::sense> imposes
		281	process-wide limits, even though the SYNOPSIS makes it clear that it works
		282	like other similar modules - only on the scope that uses them.
		283
		284	So, no, we don't - nobody is forced to use this module, and using a module
		285	that relies on common::sense does not impose anything on you.
		286
		287	=item Why do you think only your notion of common::sense is valid?
		288
		289	Well, we don't, and have clearly written this in the documentation to
		290	every single release. We were just faster than anybody else w.r.t. to
		291	grabbing the namespace.
		292
		293	=item But everybody knows that you have to use strict and use warnings,
		294	why do you disable them?
		295
		296	Well, we don't do this either - we selectively disagree with the
		297	usefulness of some warnings over others. This module is aimed at
		298	experienced Perl programmers, not people migrating from other languages
		299	who might be surprised about stuff such as C<undef>.
		300
		301	In fact, this module is considerably I<more> strict than the canonical
		302	C<use strict; use warnings>, as it makes all warnings fatal in nature, so
		303	you can get away with as many things as with the canonical approach.
		304
		305	This was not implemented in version 1.0 because of the daunting number
		306	of warning categories and the difficulty in getting exactly the set of
		307	warnings you wish (i.e. look at the SYNOPSIS in how complicated it is to
		308	get a specific set of warnings - it is not reasonable to put this into
		309	every module, the maintainance effort would be enourmous).
		310
		311	=item But many modules C<use strict> or C<use warnings>, so the memory
		312	savings do not apply?
		313
		314	I am suddenly so sad.
		315
		316	But yes, that's true. Fortunately C<common::sense> still uses only a
		317	miniscule amount of RAM.
		318
		319	=item But it adds another dependency to your modules!
		320
		321	It's a fact, yeah. But it's trivial to install, most popular modules have
		322	many more dependencies and we consider dependencies a good thing - it
		323	leads to better APIs, more thought about interworking of modules and so
		324	on.
		325
		326	=item But! But!
		327
		328	Yeah, we know.
		329
		330	=back
178		331
179	=head1 AUTHOR	332	=head1 AUTHOR
180		333
181	Marc Lehmann <schmorp@schmorp.de>	334	Marc Lehmann <schmorp@schmorp.de>
182	http://home.schmorp.de/	335	http://home.schmorp.de/
183		336
184	Robin Redeker, "<elmex at ta-sa.org>".	337	Robin Redeker, "<elmex at ta-sa.org>".
185		338
186
187	=cut	339	=cut
188		340

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Comparing common-sense/sense.pm (file contents): Revision 1.9 by root, Sat Aug 15 14:12:10 2009 UTC vs. Revision 1.19 by root, Mon Oct 5 15:02:32 2009 UTC

Diff Legend

Comparing common-sense/sense.pm (file contents):
Revision 1.9 by root, Sat Aug 15 14:12:10 2009 UTC vs.
Revision 1.19 by root, Mon Oct 5 15:02:32 2009 UTC