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

Comparing common-sense/sense.pm (file contents):
Revision 1.14 by root, Tue Sep 1 13:54:56 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 no warnings	32	=item use strict qw(subs vars)
		33
		34	Using C<use strict> is definitely common sense, but C<use strict
		35	'refs'> definitely overshoots its usefulness. After almost two
		36	decades of Perl hacking, we decided that it does more harm than being
		37	useful. Specifically, constructs like these:
		38
		39	@{ $var->[0] }
		40
		41	Must be written like this (or similarly), when C<use strict 'refs'> is in
		42	scope, and C<$var> can legally be C<undef>:
		43
		44	@{ $var->[0] \|\| [] }
		45
		46	This is annoying, and doesn't shield against obvious mistakes such as
		47	using C<"">, so one would even have to write (at least for the time
		48	being):
		49
		50	@{ defined $var->[0] ? $var->[0] : [] }
		51
		52	... which nobody with a bit of common sense would consider
		53	writing: clear code is clearly something else.
		54
		55	Curiously enough, sometimes perl is not so strict, as this works even with
		56	C<use strict> in scope:
		57
		58	for (@{ $var->[0] }) { ...
		59
		60	If that isn't hypocrisy! And all that from a mere program!
		61
		62
		63	=item use feature qw(say state given)
		64
		65	We found it annoying that we always have to enable extra features. If
		66	something breaks because it didn't anticipate future changes, so be
		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
		71	Few modules that are not actively maintained work with newer versions of
		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.
		74
		75	If your code isn't alive, it's dead, Jim - be an active maintainer.
		76
		77
		78	=item no warnings, but a lot of new errors
24		79
25	Ah, the dreaded warnings. Even worse, the horribly dreaded C<-w>	80	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	81	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	82	certainly there are useful ones), a lot of warnings simply go against the
28	spirit of Perl.	83	spirit of Perl.
29		84
30	Most prominently, the warnings related to C<undef>. There is nothing wrong	85	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	86	with C<undef>: it has well-defined semantics, it is useful, and spitting
32	out warnings you never asked for is just evil.	87	out warnings you never asked for is just evil.
33		88
34	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
35	C<-w> and forcing his bad standards on our code. No will do. Really, the	90	past, to avoid somebody accidentally using and forcing his bad standards
36	C<-w> switch should only enable wanrings for the main program.	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.
37		94
38	Funnily enough, L<perllexwarn> explicitly mentions C<-w> (and not in a	95	Funnily enough, L<perllexwarn> explicitly mentions C<-w> (and not in a
39	favourable way), but standard utilities, such as L<prove>, or MakeMaker	96	favourable way, calling it outright "wrong"), but standard utilities, such
40	when running C<make test> enable them blindly.	97	as L<prove>, or MakeMaker when running C<make test>, still enable them
		98	blindly.
41		99
42	=item use strict qw(subs vars)	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.
43		103
44	Using C<use strict> is definitely common sense, but C<use strict	104	This resulted in the rather impressive list in the SYNOPSIS. When we
45	'refs'> definitely overshoots its usefulness. After almost two	105	weren't sure, we didn't include the warning, so the list might grow in
46	decades of Perl hacking, we decided that it does more harm than being	106	the future (we might have made a mistake, too, so the list might shrink
47	useful. Specifically, constructs like these:	107	as well).
48		108
49	@{ $var->[0] }	109	Note the presence of C<FATAL> in the list: we do not think that the
		110	conditions caught by these warnings are worthy of a warning, we I<insist>
		111	that they are worthy of I<stopping> your program, I<instantly>. They are
		112	I<bugs>!
50		113
51	Must be written like this (or similarly), when C<use strict 'refs'> is in	114	Therefore we consider C<common::sense> to be much stricter than C<use
52	scope, and C<$var> can legally be C<undef>:	115	warnings>, which is good if you are into strict things (we are not,
		116	actually, but these things tend to be subjective).
53		117
54	@{ $var->[0] \|\| [] }	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:
55		122
56	This is annoying, and doesn't shield against obvious mistakes such as	123	$fmt =~ s/([^\s\[])\[( [^\]] )\]/\x0$1\x1$2\x0/xgo;
57	using C<"">, so one would even have to write (at least for the time
58	being):
59		124
60	@{ defined $var->[0] ? $var->[0] : [] }	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.
61		127
62	... which nobody with a bit of common sense would consider
63	writing.
64
65	Curiously enough, sometimes perl is not so strict, as this works even with
66	C<use strict> in scope:
67
68	for (@{ $var->[0] }) { ...
69
70	If that isn't hipocrasy! And all that from a mere program!
71
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	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		128
86	=item mucho reduced memory usage	129	=item mucho reduced memory usage
87		130
88	Just using all those pragmas mentioned in the SYNOPSIS together wastes	131	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	132	<blink>I<< B<776> kilobytes >></blink> of precious memory in my perl, for
…		…
100		143
101	=cut	144	=cut
102		145
103	package common::sense;	146	package common::sense;
104		147
105	our $VERSION = '1.0';	148	our $VERSION = '2.01';
		149
		150	# paste this into perl to find bitmask
106		151
107	# no warnings;	152	# no warnings;
108	# use warnings qw(FATAL closed threads internal debugging pack substr malloc unopened portable prototype	153	# use warnings qw(FATAL closed threads internal debugging pack substr malloc unopened portable prototype
109	# inplace io pipe unpack regexp deprecated exiting redefine glob digit printf	154	# inplace io pipe unpack regexp deprecated exiting glob digit printf
110	# utf8 layer reserved parenthesis taint closure semicolon);	155	# utf8 layer reserved parenthesis taint closure semicolon);
111	# no warnings qw(exec newline);	156	# no warnings qw(exec newline);
112	# BEGIN { warn join "", map "\\x$_", unpack "(H2)*", ${^WARNING_BITS}; exit 0 };	157	# BEGIN { warn join "", map "\\x$_", unpack "(H2)*", ${^WARNING_BITS}; exit 0 };
113		158
114	# overload should be included	159	# overload should be included
115		160
116	sub import {	161	sub import {
117	# verified with perl 5.8.0, 5.10.0	162	# verified with perl 5.8.0, 5.10.0
118	${^WARNING_BITS} = "\xfc\x3f\xf3\x00\xcf\xf3\xcf\xc0\xf3\xfc\x33\x03";	163	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\xfc\x3f\xf3\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x03";
119		164
120	# use strict vars subs	165	# use strict vars subs
121	$^H \|= 0x00000600;	166	$^H \|= 0x00000600;
122		167
123	# use feature	168	# use feature
…		…
139	=head1 STABILITY AND FUTURE VERSIONS	184	=head1 STABILITY AND FUTURE VERSIONS
140		185
141	Future versions might change just about everything in this module. We	186	Future versions might change just about everything in this module. We
142	might test our modules and upload new ones working with newer versions of	187	might test our modules and upload new ones working with newer versions of
143	this module, and leave you standing in the rain because we didn't tell	188	this module, and leave you standing in the rain because we didn't tell
144	you.	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.
145		191
146	Most likely, we will pick a few useful warnings, instead of just disabling
147	all of them. And maybe we will load some nifty modules that try to emulate	192	Maybe we will load some nifty modules that try to emulate C<say> or so
148	C<say> or so with perls older than 5.10 (this module, of course, should	193	with perls older than 5.10 (this module, of course, should work with older
149	work with older perl versions - supporting 5.8 for example is just common	194	perl versions - supporting 5.8 for example is just common sense at this
150	sense at this time. Maybe not in the future, but of course you can trust	195	time. Maybe not in the future, but of course you can trust our common
151	our common sense to be consistent with, uhm, our opinion).	196	sense to be consistent with, uhm, our opinion).
152		197
153	=head1 WHAT OTHER PEOPLE HAD TO SAY ABOUT THIS MODULE	198	=head1 WHAT OTHER PEOPLE HAD TO SAY ABOUT THIS MODULE
154		199
155	apeiron	200	apeiron
156		201
…		…
158	"I hope common::sense is a joke."	203	"I hope common::sense is a joke."
159		204
160	crab	205	crab
161		206
162	"i wonder how it would be if joerg schilling wrote perl modules."	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."
163		214
164	H.Merijn Brand	215	H.Merijn Brand
165		216
166	"Just one more reason to drop JSON::XS from my distribution list"	217	"Just one more reason to drop JSON::XS from my distribution list"
167		218
…		…
200		251
201	acme	252	acme
202		253
203	"THERE IS NO 'no common::sense'!!!! !!!! !!"	254	"THERE IS NO 'no common::sense'!!!! !!!! !!"
204		255
205	apeiron (meta-comment)	256	apeiron (meta-comment about us commenting^Wquoting his comment)
206		257
207	How about quoting this: get a clue, you fucktarded amoeba.	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
208		340
209	=head1 AUTHOR	341	=head1 AUTHOR
210		342
211	Marc Lehmann <schmorp@schmorp.de>	343	Marc Lehmann <schmorp@schmorp.de>
212	http://home.schmorp.de/	344	http://home.schmorp.de/

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Comparing common-sense/sense.pm (file contents): Revision 1.14 by root, Tue Sep 1 13:54:56 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 1.14 by root, Tue Sep 1 13:54:56 2009 UTC vs.
Revision 1.21 by root, Fri Oct 30 02:58:05 2009 UTC