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

Comparing common-sense/sense.pm (file contents):
Revision 1.2 by root, Thu Jul 9 17:25:48 2009 UTC vs.
Revision 1.21 by root, Fri Oct 30 02:58:05 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. In fact, after working out details on which warnings and strict
		25	modes to enable and make fatal, we found that we (and our code written so
		26	far, and others) fully agree on every option, even though we never used
		27	warnings before, so it seems this module indeed reflects a "common" sense
		28	among some long-time Perl coders.
20		29
21	=over 4	30	=over 4
22		31
23	=item use strict qw(subs vars)	32	=item use strict qw(subs vars)
24		33
25	Using C<use strict> is definitely common sense, but C<use strict	34	Using C<use strict> is definitely common sense, but C<use strict
26	'refs'> definitely overshoots it's usefulness. After almost two	35	'refs'> definitely overshoots its usefulness. After almost two
27	decades of Perl hacking, we decided that it does more harm than being	36	decades of Perl hacking, we decided that it does more harm than being
28	useful. Specifically, constructs like these:	37	useful. Specifically, constructs like these:
29		38
30	@{ $var->[0] }	39	@{ $var->[0] }
31		40
32	Must be written like this, when C<use strict 'refs'> is in scope, and	41	Must be written like this (or similarly), when C<use strict 'refs'> is in
33	C<$var> can legally be C<undef>:	42	scope, and C<$var> can legally be C<undef>:
34		43
35	@{ $var->[0] \|\| [] }	44	@{ $var->[0] \|\| [] }
36		45
37	This is annoying, and doesn't shield against obvious mistakes such as	46	This is annoying, and doesn't shield against obvious mistakes such as
38	using C<"">, so one would even have to write:	47	using C<"">, so one would even have to write (at least for the time
		48	being):
39		49
40	@{ defined $var->[0] ? $var->[0] : [] }	50	@{ defined $var->[0] ? $var->[0] : [] }
41		51
42	... which nobody with a bit of common sense would consider	52	... which nobody with a bit of common sense would consider
		53	writing: clear code is clearly something else.
		54
43	writing. Curiously enough, sometimes, perl is not so strict, as this works	55	Curiously enough, sometimes perl is not so strict, as this works even with
44	even with C<use strict> in scope:	56	C<use strict> in scope:
45		57
46	for (@{ $var->[0] }) { ...	58	for (@{ $var->[0] }) { ...
47		59
48	If that isnt hipocrasy! And all that from a mere program!	60	If that isn't hypocrisy! And all that from a mere program!
		61
49		62
50	=item use feature qw(say state given)	63	=item use feature qw(say state given)
51		64
52	We found it annoying that we always have to enable extra features. If	65	We found it annoying that we always have to enable extra features. If
53	something breaks because it didn't anticipate future changes, so be	66	something breaks because it didn't anticipate future changes, so be
54	it. 5.10 broke almost all our XS modules and nobody cared either - and few	67	it. 5.10 broke almost all our XS modules and nobody cared either (or at
		68	least I know of nobody who really complained about gratuitous changes -
		69	as opposed to bugs).
		70
55	modules that are no longer maintained work with newer versions of Perl,	71	Few modules that are not actively maintained work with newer versions of
56	regardless of use feature.	72	Perl, regardless of use feature or not, so a new major perl release means
		73	changes to many modules - new keywords are just the tip of the iceberg.
57		74
58	If your code isn'talive, it's dead, jim.	75	If your code isn't alive, it's dead, Jim - be an active maintainer.
59		76
60	=item no warnings
61		77
		78	=item no warnings, but a lot of new errors
		79
62	The dreaded warnings. Even worse, the horribly dreaded C<-w> switch. Even	80	Ah, the dreaded warnings. Even worse, the horribly dreaded C<-w>
63	though we don't care if other people use warnings (and certainly there are	81	switch: Even though we don't care if other people use warnings (and
64	useful ones), a lot of warnings simply go against the spirit of Perl, most	82	certainly there are useful ones), a lot of warnings simply go against the
		83	spirit of Perl.
		84
65	prominently, the warnings related to C<undef>. There is nothing wrong with	85	Most prominently, the warnings related to C<undef>. There is nothing wrong
66	C<undef>: it has well-defined semantics, it is useful, and spitting out	86	with C<undef>: it has well-defined semantics, it is useful, and spitting
67	warnings you never asked for is just evil.	87	out warnings you never asked for is just evil.
68		88
69	So every module needs C<no warnings> to avoid somebody accidentally using	89	The result was that every one of our modules did C<no warnings> in the
70	C<-w> and forcing his bad standards on our code. No will do.	90	past, to avoid somebody accidentally using and forcing his bad standards
		91	on our code. Of course, this switched off all warnings, even the useful
		92	ones. Not a good situation. Really, the C<-w> switch should only enable
		93	warnings for the main program only.
71		94
72	(Also, why isn't this a C<use feature> switch? Adding warnings is	95	Funnily enough, L<perllexwarn> explicitly mentions C<-w> (and not in a
73	apparently considered O.K., even if it breaks your programs).	96	favourable way, calling it outright "wrong"), but standard utilities, such
		97	as L<prove>, or MakeMaker when running C<make test>, still enable them
		98	blindly.
74		99
75	=item much less memory	100	For version 2 of common::sense, we finally sat down a few hours and went
		101	through I<every single warning message>, identifiying - according to
		102	common sense - all the useful ones.
76		103
77	Just using all those pragmas together waste <blink>I<< B<776> kilobytes	104	This resulted in the rather impressive list in the SYNOPSIS. When we
78	>></blink> of precious memory in my perl, for I<every single perl process	105	weren't sure, we didn't include the warning, so the list might grow in
79	using our code>, which on our machines, is a lot.	106	the future (we might have made a mistake, too, so the list might shrink
		107	as well).
		108
		109	Note the presence of C<FATAL> in the list: we do not think that the
		110	conditions caught by these warnings are worthy of a warning, we I<insist>
		111	that they are worthy of I<stopping> your program, I<instantly>. They are
		112	I<bugs>!
		113
		114	Therefore we consider C<common::sense> to be much stricter than C<use
		115	warnings>, which is good if you are into strict things (we are not,
		116	actually, but these things tend to be subjective).
		117
		118	After deciding on the list, we ran the module against all of our code that
		119	uses C<common::sense> (that is almost all of our code), and found only one
		120	occurence where one of them caused a problem: one of elmex's (unreleased)
		121	modules contained:
		122
		123	$fmt =~ s/([^\s\[])\[( [^\]] )\]/\x0$1\x1$2\x0/xgo;
		124
		125	We quickly agreed that indeed the code should be changed, even though it
		126	happened to do the right thing when the warning was switched off.
		127
		128
		129	=item mucho reduced memory usage
		130
		131	Just using all those pragmas mentioned in the SYNOPSIS together wastes
		132	<blink>I<< B<776> kilobytes >></blink> of precious memory in my perl, for
		133	I<every single perl process using our code>, which on our machines, is a
		134	lot. In comparison, this module only uses I<< B<four> >> kilobytes (I even
		135	had to write it out so it looks like more) of memory on the same platform.
80		136
81	The money/time/effort/electricity invested in these gigabytes (probably	137	The money/time/effort/electricity invested in these gigabytes (probably
82	petabytes globally!) of wasted memory could easily save 42 trees, and a	138	petabytes globally!) of wasted memory could easily save 42 trees, and a
83	kitten!	139	kitten!
84		140
		141	Unfortunately, until everybods applies more common sense, there will still
		142	often be modules that pull in the monster pragmas. But one can hope...
		143
85	=cut	144	=cut
86		145
87	package common::sense;	146	package common::sense;
88		147
89	our $VERSION = '0.03';	148	our $VERSION = '2.01';
		149
		150	# paste this into perl to find bitmask
		151
		152	# no warnings;
		153	# use warnings qw(FATAL closed threads internal debugging pack substr malloc unopened portable prototype
		154	# inplace io pipe unpack regexp deprecated exiting glob digit printf
		155	# utf8 layer reserved parenthesis taint closure semicolon);
		156	# no warnings qw(exec newline);
		157	# BEGIN { warn join "", map "\\x$_", unpack "(H2)*", ${^WARNING_BITS}; exit 0 };
		158
		159	# overload should be included
90		160
91	sub import {	161	sub import {
92	${^WARNING_BITS} ^= ${^WARNING_BITS};	162	# verified with perl 5.8.0, 5.10.0
		163	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\xfc\x3f\xf3\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x03";
		164
		165	# use strict vars subs
		166	$^H \|= 0x00000600;
		167
		168	# use feature
		169	$^H{feature_switch} =
		170	$^H{feature_say} =
		171	$^H{feature_state} = 1;
93	}	172	}
94		173
95	=cut
96
97	1;	174	1;
98		175
99	=back	176	=back
100		177
101	=head1 EXAMPLE	178	=head1 THERE IS NO 'no common::sense'!!!! !!!! !!
102		179
103	There really should be a complete C/XS example. Bug me about it.	180	This module doesn't offer an unimport. First of all, it wastes even more
		181	memory, second, and more importantly, who with even a bit of common sense
		182	would want no common sense?
104		183
105	=head1 IMPLEMENTATION DETAILS AND LIMITATIONS	184	=head1 STABILITY AND FUTURE VERSIONS
106		185
107	This module works by "hijacking" SIGKILL, which is guaranteed to be always	186	Future versions might change just about everything in this module. We
108	available in perl, but also cannot be caught, so is always available.	187	might test our modules and upload new ones working with newer versions of
		188	this module, and leave you standing in the rain because we didn't tell
		189	you. In fact, we did so when switching from 1.0 to 2.0, which enabled gobs
		190	of warnings, and made them FATAL on top.
109		191
110	Basically, this module fakes the receive of a SIGKILL signal and	192	Maybe we will load some nifty modules that try to emulate C<say> or so
111	then catches it. This makes normal signal handling slower (probably	193	with perls older than 5.10 (this module, of course, should work with older
112	unmeasurably), but has the advantage of not requiring a special runops nor	194	perl versions - supporting 5.8 for example is just common sense at this
113	slowing down normal perl execution a bit.	195	time. Maybe not in the future, but of course you can trust our common
		196	sense to be consistent with, uhm, our opinion).
114		197
115	It assumes that C<sig_atomic_t> and C<int> are both exception-safe to	198	=head1 WHAT OTHER PEOPLE HAD TO SAY ABOUT THIS MODULE
116	modify (C<sig_atomic_> is used by this module, and perl itself uses	199
117	C<int>, so we can assume that this is quite portable, at least w.r.t.	200	apeiron
118	signals).	201
		202	"... wow"
		203	"I hope common::sense is a joke."
		204
		205	crab
		206
		207	"i wonder how it would be if joerg schilling wrote perl modules."
		208
		209	Adam Kennedy
		210
		211	"Very interesting, efficient, and potentially something I'd use all the time."
		212	[...]
		213	"So no common::sense for me, alas."
		214
		215	H.Merijn Brand
		216
		217	"Just one more reason to drop JSON::XS from my distribution list"
		218
		219	Pista Palo
		220
		221	"Something in short supply these days..."
		222
		223	Steffen Schwigon
		224
		225	"This module is quite for sure not just a repetition of all the other
		226	'use strict, use warnings'-approaches, and it's also not the opposite.
		227	[...] And for its chosen middle-way it's also not the worst name ever.
		228	And everything is documented."
		229
		230	BKB
		231
		232	"[Deleted - thanks to Steffen Schwigon for pointing out this review was
		233	in error.]"
		234
		235	Somni
		236
		237	"the arrogance of the guy"
		238	"I swear he tacked somenoe else's name onto the module
		239	just so he could use the royal 'we' in the documentation"
		240
		241	dngor
		242
		243	"Heh. '"<elmex at ta-sa.org>"' The quotes are semantic
		244	distancing from that e-mail address."
		245
		246	Jerad Pierce
		247
		248	"Awful name (not a proper pragma), and the SYNOPSIS doesn't tell you
		249	anything either. Nor is it clear what features have to do with "common
		250	sense" or discipline."
		251
		252	acme
		253
		254	"THERE IS NO 'no common::sense'!!!! !!!! !!"
		255
		256	apeiron (meta-comment about us commenting^Wquoting his comment)
		257
		258	How about quoting this: get a clue, you fucktarded amoeba.
		259
		260	quanth
		261
		262	common sense is beautiful, json::xs is fast, Anyevent, EV are fast and
		263	furious. I love mlehmannware ;)
		264
		265	=head1 FREQUQNTLY ASKED QUESTIONS
		266
		267	Or frequently-come-up confusions.
		268
		269	=over 4
		270
		271	=item Is this module meant to be serious?
		272
		273	Yes, we would have put it under the C<Acme::> namespace otherwise.
		274
		275	=item But the manpage is written in a funny/stupid/... way?
		276
		277	This was meant to make it clear that our common sense is a subjective
		278	thing and other people can use their own notions, taking the steam out
		279	of anybody who might be offended (as some people are always offended no
		280	matter what you do).
		281
		282	This was a failure.
		283
		284	But we hope the manpage still is somewhat entertaining even though it
		285	explains boring rationale.
		286
		287	=item Why do you impose your conventions on my code?
		288
		289	For some reason people keep thinking that C<common::sense> imposes
		290	process-wide limits, even though the SYNOPSIS makes it clear that it works
		291	like other similar modules - only on the scope that uses them.
		292
		293	So, no, we don't - nobody is forced to use this module, and using a module
		294	that relies on common::sense does not impose anything on you.
		295
		296	=item Why do you think only your notion of common::sense is valid?
		297
		298	Well, we don't, and have clearly written this in the documentation to
		299	every single release. We were just faster than anybody else w.r.t. to
		300	grabbing the namespace.
		301
		302	=item But everybody knows that you have to use strict and use warnings,
		303	why do you disable them?
		304
		305	Well, we don't do this either - we selectively disagree with the
		306	usefulness of some warnings over others. This module is aimed at
		307	experienced Perl programmers, not people migrating from other languages
		308	who might be surprised about stuff such as C<undef>.
		309
		310	In fact, this module is considerably I<more> strict than the canonical
		311	C<use strict; use warnings>, as it makes all warnings fatal in nature, so
		312	you can get away with as many things as with the canonical approach.
		313
		314	This was not implemented in version 1.0 because of the daunting number
		315	of warning categories and the difficulty in getting exactly the set of
		316	warnings you wish (i.e. look at the SYNOPSIS in how complicated it is to
		317	get a specific set of warnings - it is not reasonable to put this into
		318	every module, the maintainance effort would be enourmous).
		319
		320	=item But many modules C<use strict> or C<use warnings>, so the memory
		321	savings do not apply?
		322
		323	I am suddenly so sad.
		324
		325	But yes, that's true. Fortunately C<common::sense> still uses only a
		326	miniscule amount of RAM.
		327
		328	=item But it adds another dependency to your modules!
		329
		330	It's a fact, yeah. But it's trivial to install, most popular modules have
		331	many more dependencies and we consider dependencies a good thing - it
		332	leads to better APIs, more thought about interworking of modules and so
		333	on.
		334
		335	=item But! But!
		336
		337	Yeah, we know.
		338
		339	=back
119		340
120	=head1 AUTHOR	341	=head1 AUTHOR
121		342
122	Marc Lehmann <schmorp@schmorp.de>	343	Marc Lehmann <schmorp@schmorp.de>
123	http://home.schmorp.de/	344	http://home.schmorp.de/
124		345
		346	Robin Redeker, "<elmex at ta-sa.org>".
		347
125	=cut	348	=cut
126		349

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Comparing common-sense/sense.pm (file contents): Revision 1.2 by root, Thu Jul 9 17:25:48 2009 UTC vs. Revision 1.21 by root, Fri Oct 30 02:58:05 2009 UTC

Diff Legend

Comparing common-sense/sense.pm (file contents):
Revision 1.2 by root, Thu Jul 9 17:25:48 2009 UTC vs.
Revision 1.21 by root, Fri Oct 30 02:58:05 2009 UTC