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

Comparing common-sense/sense.pm (file contents):
Revision 1.16 by root, Tue Sep 1 19:10:02 2009 UTC vs.
Revision 1.24 by root, Wed Dec 2 17:43:20 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	14	# use warnings qw(FATAL closed threads internal debugging pack substr malloc
15	# unopened portable prototype inplace io pipe unpack regexp	15	# portable prototype inplace io pipe unpack regexp
16	# deprecated exiting glob digit printf utf8 layer	16	# deprecated exiting glob digit printf utf8 layer
17	# reserved parenthesis taint closure semicolon);	17	# reserved parenthesis taint closure semicolon);
18	# no warnings qw(exec newline);	18	# no warnings qw(exec newline unopened);
19		19
20	=head1 DESCRIPTION	20	=head1 DESCRIPTION
21		21
22	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
23	two typical (or not so typical - use your common sense) specimens of Perl	23	two typical (or not so typical - use your common sense) specimens of Perl
24	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.
		29
		30	The basic philosophy behind the choices made in common::sense can be
		31	summarised as: "enforcing strict policies to catch as many bugs as
		32	possible, while at the same time, not limiting the expressive power
		33	available to the programmer".
		34
		35	Two typical examples of this philosophy are uninitialised and malloc
		36	warnings:
		37
		38	C<undef> is a well-defined feature of perl, and enabling warnings for
		39	using it rarely catches any bugs, but considerably limits you in what you
		40	can do, so uninitialised warnings are disabled.
		41
		42	Freeing something twice on the C level is a serious bug, usually causing
		43	memory corruption. It often leads to side effects much later in the
		44	program and there are no advantages to not reporting this, so malloc
		45	warnings are fatal by default.
		46
		47	What follows is a more thorough discussion of what this module does,
		48	and why it does it, and what the advantages (and disadvantages) of this
		49	approach are.
25		50
26	=over 4	51	=over 4
27		52
28	=item use strict qw(subs vars)	53	=item use strict qw(subs vars)
29		54
…		…
41		66
42	This is annoying, and doesn't shield against obvious mistakes such as	67	This is annoying, and doesn't shield against obvious mistakes such as
43	using C<"">, so one would even have to write (at least for the time	68	using C<"">, so one would even have to write (at least for the time
44	being):	69	being):
45		70
46	@{ defined $var->[0] ? $var->[0] : [] }	71	@{ defined $var->[0] ? $var->[0] : [] }
47		72
48	... which nobody with a bit of common sense would consider	73	... which nobody with a bit of common sense would consider
49	writing.	74	writing: clear code is clearly something else.
50		75
51	Curiously enough, sometimes perl is not so strict, as this works even with	76	Curiously enough, sometimes perl is not so strict, as this works even with
52	C<use strict> in scope:	77	C<use strict> in scope:
53		78
54	for (@{ $var->[0] }) { ...	79	for (@{ $var->[0] }) { ...
…		…
68	Perl, regardless of use feature or not, so a new major perl release means	93	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.	94	changes to many modules - new keywords are just the tip of the iceberg.
70		95
71	If your code isn't alive, it's dead, Jim - be an active maintainer.	96	If your code isn't alive, it's dead, Jim - be an active maintainer.
72		97
		98	But nobody forces you to use those extra features in modules meant for
		99	older versions of perl - common::sense of course works there as well.
		100	There is also an important other mode where having additional features by
		101	default is useful: commandline hacks and internal use scripts: See "much
		102	reduced typing", below.
		103
73		104
74	=item no warnings, but a lot of new errors	105	=item no warnings, but a lot of new errors
75		106
76	Ah, the dreaded warnings. Even worse, the horribly dreaded C<-w>	107	Ah, the dreaded warnings. Even worse, the horribly dreaded C<-w>
77	switch: Even though we don't care if other people use warnings (and	108	switch: Even though we don't care if other people use warnings (and
…		…
120		151
121	We quickly agreed that indeed the code should be changed, even though it	152	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.	153	happened to do the right thing when the warning was switched off.
123		154
124		155
		156	=item much reduced typing
		157
		158	Especially with version 2.0 of common::sense, the amount of boilerplate
		159	code you need to add to gte I<this> policy is daunting. Nobody would write
		160	this out in throwaway scripts, commandline hacks or in quick internal-use
		161	scripts.
		162
		163	By using common::sense you get a defined set of policies (ours, but maybe
		164	yours, too, if you accept them), and they are easy to apply to your
		165	scripts: typing C<use common::sense;> is even shorter than C<use warnings;
		166	use strict; use feature ...>.
		167
		168	And you can immediately use the features of your installed perl, which
		169	is more difficult in code you release, but not usually an issue for
		170	internal-use code (downgrades of your production perl should be rare,
		171	right?).
		172
		173
125	=item mucho reduced memory usage	174	=item mucho reduced memory usage
126		175
127	Just using all those pragmas mentioned in the SYNOPSIS together wastes	176	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	177	<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	178	I<every single perl process using our code>, which on our machines, is a
…		…
139		188
140	=cut	189	=cut
141		190
142	package common::sense;	191	package common::sense;
143		192
144	our $VERSION = '2.0';	193	our $VERSION = '2.03';
145		194
146	# paste this into pelr to find bitmask	195	# paste this into perl to find bitmask
147		196
148	# no warnings;	197	# no warnings;
149	# use warnings qw(FATAL closed threads internal debugging pack substr malloc unopened portable prototype	198	# use warnings qw(FATAL closed threads internal debugging pack substr malloc portable prototype
150	# inplace io pipe unpack regexp deprecated exiting glob digit printf	199	# inplace io pipe unpack regexp deprecated exiting glob digit printf
151	# utf8 layer reserved parenthesis taint closure semicolon);	200	# utf8 layer reserved parenthesis taint closure semicolon);
152	# no warnings qw(exec newline);	201	# no warnings qw(exec newline unopened);
153	# BEGIN { warn join "", map "\\x$_", unpack "(H2)*", ${^WARNING_BITS}; exit 0 };	202	# BEGIN { warn join "", map "\\x$_", unpack "(H2)*", ${^WARNING_BITS}; exit 0 };
154		203
155	# overload should be included	204	# overload should be included
156		205
157	sub import {	206	sub import {
158	# verified with perl 5.8.0, 5.10.0	207	# verified with perl 5.8.0, 5.10.0
159	${^WARNING_BITS} = "\xfc\x3f\xf3\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x03";	208	${^WARNING_BITS} ^= ${^WARNING_BITS} ^ "\xfc\x3f\x33\x00\x0f\xf3\xcf\xc0\xf3\xfc\x33\x03";
160		209
161	# use strict vars subs	210	# use strict vars subs
162	$^H \|= 0x00000600;	211	$^H \|= 0x00000600;
163		212
164	# use feature	213	# use feature
…		…
200		249
201	crab	250	crab
202		251
203	"i wonder how it would be if joerg schilling wrote perl modules."	252	"i wonder how it would be if joerg schilling wrote perl modules."
204		253
		254	Adam Kennedy
		255
		256	"Very interesting, efficient, and potentially something I'd use all the time."
		257	[...]
		258	"So no common::sense for me, alas."
		259
205	H.Merijn Brand	260	H.Merijn Brand
206		261
207	"Just one more reason to drop JSON::XS from my distribution list"	262	"Just one more reason to drop JSON::XS from my distribution list"
208		263
209	Pista Palo	264	Pista Palo
…		…
226		281
227	"the arrogance of the guy"	282	"the arrogance of the guy"
228	"I swear he tacked somenoe else's name onto the module	283	"I swear he tacked somenoe else's name onto the module
229	just so he could use the royal 'we' in the documentation"	284	just so he could use the royal 'we' in the documentation"
230		285
		286	Anonymous Monk
		287
		288	"You just gotta love this thing, its got META.json!!!"
		289
231	dngor	290	dngor
232		291
233	"Heh. '"<elmex at ta-sa.org>"' The quotes are semantic	292	"Heh. '"<elmex at ta-sa.org>"' The quotes are semantic
234	distancing from that e-mail address."	293	distancing from that e-mail address."
235		294
…		…
243		302
244	"THERE IS NO 'no common::sense'!!!! !!!! !!"	303	"THERE IS NO 'no common::sense'!!!! !!!! !!"
245		304
246	apeiron (meta-comment about us commenting^Wquoting his comment)	305	apeiron (meta-comment about us commenting^Wquoting his comment)
247		306
248	How about quoting this: get a clue, you fucktarded amoeba.	307	"How about quoting this: get a clue, you fucktarded amoeba."
		308
		309	quanth
		310
		311	"common sense is beautiful, json::xs is fast, Anyevent, EV are fast and
		312	furious. I love mlehmannware ;)"
		313
		314	=head1 FREQUQNTLY ASKED QUESTIONS
		315
		316	Or frequently-come-up confusions.
		317
		318	=over 4
		319
		320	=item Is this module meant to be serious?
		321
		322	Yes, we would have put it under the C<Acme::> namespace otherwise.
		323
		324	=item But the manpage is written in a funny/stupid/... way?
		325
		326	This was meant to make it clear that our common sense is a subjective
		327	thing and other people can use their own notions, taking the steam out
		328	of anybody who might be offended (as some people are always offended no
		329	matter what you do).
		330
		331	This was a failure.
		332
		333	But we hope the manpage still is somewhat entertaining even though it
		334	explains boring rationale.
		335
		336	=item Why do you impose your conventions on my code?
		337
		338	For some reason people keep thinking that C<common::sense> imposes
		339	process-wide limits, even though the SYNOPSIS makes it clear that it works
		340	like other similar modules - only on the scope that uses them.
		341
		342	So, no, we don't - nobody is forced to use this module, and using a module
		343	that relies on common::sense does not impose anything on you.
		344
		345	=item Why do you think only your notion of common::sense is valid?
		346
		347	Well, we don't, and have clearly written this in the documentation to
		348	every single release. We were just faster than anybody else w.r.t. to
		349	grabbing the namespace.
		350
		351	=item But everybody knows that you have to use strict and use warnings,
		352	why do you disable them?
		353
		354	Well, we don't do this either - we selectively disagree with the
		355	usefulness of some warnings over others. This module is aimed at
		356	experienced Perl programmers, not people migrating from other languages
		357	who might be surprised about stuff such as C<undef>. On the other hand,
		358	this does not exclude the usefulness of this module for total newbies, due
		359	to its strictness in enforcing policy, while at the same time not limiting
		360	the expresive power of perl.
		361
		362	This module is considerably I<more> strict than the canonical C<use
		363	strict; use warnings>, as it makes all its warnings fatal in nature, so
		364	you can not get away with as many things as with the canonical approach.
		365
		366	This was not implemented in version 1.0 because of the daunting number
		367	of warning categories and the difficulty in getting exactly the set of
		368	warnings you wish (i.e. look at the SYNOPSIS in how complicated it is to
		369	get a specific set of warnings - it is not reasonable to put this into
		370	every module, the maintainance effort would be enourmous).
		371
		372	=item But many modules C<use strict> or C<use warnings>, so the memory
		373	savings do not apply?
		374
		375	I am suddenly so sad.
		376
		377	But yes, that's true. Fortunately C<common::sense> still uses only a
		378	miniscule amount of RAM.
		379
		380	=item But it adds another dependency to your modules!
		381
		382	It's a fact, yeah. But it's trivial to install, most popular modules have
		383	many more dependencies and we consider dependencies a good thing - it
		384	leads to better APIs, more thought about interworking of modules and so
		385	on.
		386
		387	=item Why do you use JSON and not YAML for your META.yml?
		388
		389	This is not true - YAML supports a large subset of JSON, and this subset
		390	is what META.yml is written in, so it would be correct to say "the
		391	META.yml is written in a common subset of YAML and JSON".
		392
		393	The META.yml follows the YAML, JSON and META.yml specifications, and is
		394	correctly parsed by CPAN, so if you have trouble with it, the problem is
		395	likely on your side.
		396
		397	=item But! But!
		398
		399	Yeah, we know.
		400
		401	=back
249		402
250	=head1 AUTHOR	403	=head1 AUTHOR
251		404
252	Marc Lehmann <schmorp@schmorp.de>	405	Marc Lehmann <schmorp@schmorp.de>
253	http://home.schmorp.de/	406	http://home.schmorp.de/

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Comparing common-sense/sense.pm (file contents): Revision 1.16 by root, Tue Sep 1 19:10:02 2009 UTC vs. Revision 1.24 by root, Wed Dec 2 17:43:20 2009 UTC

Diff Legend

Comparing common-sense/sense.pm (file contents):
Revision 1.16 by root, Tue Sep 1 19:10:02 2009 UTC vs.
Revision 1.24 by root, Wed Dec 2 17:43:20 2009 UTC