FM / pod

/usr/share/perl5/pod

Name	Size	Mode	Actions
a2p.pod	6107	0644	edit dl rm
perl.pod	15748	0644	edit dl rm
perl56delta.pod	107184	0644	edit dl rm
perl58delta.pod	114908	0644	edit dl rm
perl561delta.pod	124697	0644	edit dl rm
perl570delta.pod	21655	0644	edit dl rm
perl571delta.pod	30382	0644	edit dl rm
perl572delta.pod	25551	0644	edit dl rm
perl573delta.pod	4644	0644	edit dl rm
perl581delta.pod	38060	0644	edit dl rm
perl582delta.pod	4470	0644	edit dl rm
perl583delta.pod	6335	0644	edit dl rm
perl584delta.pod	7363	0644	edit dl rm
perl585delta.pod	5889	0644	edit dl rm
perl586delta.pod	4651	0644	edit dl rm
perl587delta.pod	8357	0644	edit dl rm
perl588delta.pod	25267	0644	edit dl rm
perl589delta.pod	53905	0644	edit dl rm
perl590delta.pod	34951	0644	edit dl rm
perl591delta.pod	11173	0644	edit dl rm
perl592delta.pod	10954	0644	edit dl rm
perl593delta.pod	17034	0644	edit dl rm
perl594delta.pod	12661	0644	edit dl rm
perl595delta.pod	18934	0644	edit dl rm
perl5004delta.pod	56240	0644	edit dl rm
perl5005delta.pod	34285	0644	edit dl rm
perl5100delta.pod	53922	0644	edit dl rm
perl5101delta.pod	43877	0644	edit dl rm
perlaix.pod	18128	0644	edit dl rm
perlamiga.pod	7031	0644	edit dl rm
perlapi.pod	169428	0644	edit dl rm
perlapio.pod	19332	0644	edit dl rm
perlapollo.pod	829	0644	edit dl rm
perlartistic.pod	6802	0644	edit dl rm
perlbeos.pod	2939	0644	edit dl rm
perlbook.pod	663	0644	edit dl rm
perlboot.pod	28355	0644	edit dl rm
perlbot.pod	11675	0644	edit dl rm
perlbs2000.pod	7929	0644	edit dl rm
perlcall.pod	55173	0644	edit dl rm
perlce.pod	9257	0644	edit dl rm
perlcheat.pod	4153	0644	edit dl rm
perlclib.pod	7684	0644	edit dl rm
perlcn.pod	4915	0644	edit dl rm
perlcommunity.pod	6398	0644	edit dl rm
perlcompile.pod	9516	0644	edit dl rm
perlcygwin.pod	28183	0644	edit dl rm
perldata.pod	36879	0644	edit dl rm
perldbmfilter.pod	4987	0644	edit dl rm
perldebguts.pod	31887	0644	edit dl rm
perldebtut.pod	21304	0644	edit dl rm
perldebug.pod	37535	0644	edit dl rm
perldelta.pod	43877	0644	edit dl rm
perldgux.pod	2821	0644	edit dl rm
perldiag.pod	183151	0644	edit dl rm
perldoc.pod	7310	0644	edit dl rm
perldos.pod	10853	0644	edit dl rm
perldsc.pod	25447	0644	edit dl rm
perlebcdic.pod	66607	0644	edit dl rm
perlembed.pod	38033	0644	edit dl rm
perlepoc.pod	3779	0644	edit dl rm
perlfaq.pod	24841	0644	edit dl rm
perlfaq1.pod	17762	0644	edit dl rm
perlfaq2.pod	21614	0644	edit dl rm
perlfaq3.pod	38534	0644	edit dl rm
perlfaq4.pod	81412	0644	edit dl rm
perlfaq5.pod	49201	0644	edit dl rm
perlfaq6.pod	38538	0644	edit dl rm
perlfaq7.pod	37588	0644	edit dl rm
perlfaq8.pod	46128	0644	edit dl rm
perlfaq9.pod	24191	0644	edit dl rm
perlfilter.pod	21140	0644	edit dl rm
perlfork.pod	11440	0644	edit dl rm
perlform.pod	16894	0644	edit dl rm
perlfreebsd.pod	1950	0644	edit dl rm
perlfunc.pod	291909	0644	edit dl rm
perlglossary.pod	112139	0644	edit dl rm
perlgpl.pod	18806	0644	edit dl rm
perlguts.pod	105182	0644	edit dl rm
perlhack.pod	121512	0644	edit dl rm
perlhaiku.pod	1504	0644	edit dl rm
perlhist.pod	38766	0644	edit dl rm
perlhpux.pod	28650	0644	edit dl rm
perlhurd.pod	1990	0644	edit dl rm
perlintern.pod	26408	0644	edit dl rm
perlintro.pod	21491	0644	edit dl rm
perliol.pod	33755	0644	edit dl rm
perlipc.pod	67761	0644	edit dl rm
perlirix.pod	4397	0644	edit dl rm
perljp.pod	8070	0644	edit dl rm
perlko.pod	7892	0644	edit dl rm
perllexwarn.pod	14435	0644	edit dl rm
perllinux.pod	1492	0644	edit dl rm
perllocale.pod	41616	0644	edit dl rm
perllol.pod	8252	0644	edit dl rm
perlmachten.pod	4500	0644	edit dl rm
perlmacos.pod	2111	0644	edit dl rm
perlmacosx.pod	11322	0644	edit dl rm
perlmint.pod	9539	0644	edit dl rm
perlmod.pod	24494	0644	edit dl rm
perlmodinstall.pod	13929	0644	edit dl rm
perlmodlib.pod	77333	0644	edit dl rm
perlmodstyle.pod	21114	0644	edit dl rm
perlmpeix.pod	15087	0644	edit dl rm
perlmroapi.pod	2959	0644	edit dl rm
perlnetware.pod	6488	0644	edit dl rm
perlnewmod.pod	11214	0644	edit dl rm
perlnumber.pod	8352	0644	edit dl rm
perlobj.pod	21813	0644	edit dl rm
perlop.pod	96225	0644	edit dl rm
perlopenbsd.pod	1207	0644	edit dl rm
perlopentut.pod	37997	0644	edit dl rm
perlos2.pod	92783	0644	edit dl rm
perlos390.pod	16074	0644	edit dl rm
perlos400.pod	4618	0644	edit dl rm
perlothrtut.pod	40657	0644	edit dl rm
perlpacktut.pod	51047	0644	edit dl rm
perlperf.pod	51328	0644	edit dl rm
perlplan9.pod	5125	0644	edit dl rm
perlpod.pod	21626	0644	edit dl rm
perlpodspec.pod	67792	0644	edit dl rm
perlport.pod	86302	0644	edit dl rm
perlpragma.pod	4320	0644	edit dl rm
perlqnx.pod	4246	0644	edit dl rm
perlre.pod	82798	0644	edit dl rm
perlreapi.pod	25427	0644	edit dl rm
perlrebackslash.pod	20109	0644	edit dl rm
perlrecharclass.pod	21909	0644	edit dl rm
perlref.pod	26465	0644	edit dl rm
perlreftut.pod	18670	0644	edit dl rm
perlreguts.pod	36877	0644	edit dl rm
perlrepository.pod	23453	0644	edit dl rm
perlrequick.pod	17617	0644	edit dl rm
perlreref.pod	11996	0644	edit dl rm
perlretut.pod	115005	0644	edit dl rm
perlriscos.pod	1511	0644	edit dl rm
perlrun.pod	49928	0644	edit dl rm
perlsec.pod	23542	0644	edit dl rm
perlsolaris.pod	29131	0644	edit dl rm
perlstyle.pod	8618	0644	edit dl rm
perlsub.pod	54222	0644	edit dl rm
perlsymbian.pod	16222	0644	edit dl rm
perlsyn.pod	31090	0644	edit dl rm
perlthrtut.pod	46510	0644	edit dl rm
perltie.pod	36665	0644	edit dl rm
perltoc.pod	642987	0644	edit dl rm
perltodo.pod	48360	0644	edit dl rm
perltooc.pod	51425	0644	edit dl rm
perltoot.pod	68625	0644	edit dl rm
perltrap.pod	41151	0644	edit dl rm
perltru64.pod	7736	0644	edit dl rm
perltw.pod	5384	0644	edit dl rm
perlunicode.pod	56169	0644	edit dl rm
perlunifaq.pod	12878	0644	edit dl rm
perluniintro.pod	32973	0644	edit dl rm
perlunitut.pod	7907	0644	edit dl rm
perlutil.pod	9881	0644	edit dl rm
perluts.pod	3180	0644	edit dl rm
perlvar.pod	59133	0644	edit dl rm
perlvmesa.pod	3952	0644	edit dl rm
perlvms.pod	52545	0644	edit dl rm
perlvos.pod	5567	0644	edit dl rm
perlwin32.pod	40809	0644	edit dl rm
perlxs.pod	74194	0644	edit dl rm
perlxstut.pod	49670	0644	edit dl rm

Edit: /usr/share/perl5/pod/perlstyle.pod (8618B)

=head1 NAME

perlstyle - Perl style guide

=head1 DESCRIPTION

Each programmer will, of course, have his or her own preferences in
regards to formatting, but there are some general guidelines that will
make your programs easier to read, understand, and maintain.

The most important thing is to run your programs under the B<-w>
flag at all times.  You may turn it off explicitly for particular
portions of code via the C<no warnings> pragma or the C<$^W> variable
if you must.  You should also always run under C<use strict> or know the
reason why not.  The C<use sigtrap> and even C<use diagnostics> pragmas
may also prove useful.

Regarding aesthetics of code lay out, about the only thing Larry
cares strongly about is that the closing curly bracket of
a multi-line BLOCK should line up with the keyword that started the construct.
Beyond that, he has other preferences that aren't so strong:

=over 4

=item *

4-column indent.

=item *

Opening curly on same line as keyword, if possible, otherwise line up.

=item *

Space before the opening curly of a multi-line BLOCK.

=item *

One-line BLOCK may be put on one line, including curlies.

=item *

No space before the semicolon.

=item *

Semicolon omitted in "short" one-line BLOCK.

=item *

Space around most operators.

=item *

Space around a "complex" subscript (inside brackets).

=item *

Blank lines between chunks that do different things.

=item *

Uncuddled elses.

=item *

No space between function name and its opening parenthesis.

=item *

Space after each comma.

=item *

Long lines broken after an operator (except C<and> and C<or>).

=item *

Space after last parenthesis matching on current line.

=item *

Line up corresponding items vertically.

=item *

Omit redundant punctuation as long as clarity doesn't suffer.

=back

Larry has his reasons for each of these things, but he doesn't claim that
everyone else's mind works the same as his does.

Here are some other more substantive style issues to think about:

=over 4

=item *

Just because you I<CAN> do something a particular way doesn't mean that
you I<SHOULD> do it that way.  Perl is designed to give you several
ways to do anything, so consider picking the most readable one.  For
instance

open(FOO,$foo) || die "Can't open $foo: $!";

is better than

die "Can't open $foo: $!" unless open(FOO,$foo);

because the second way hides the main point of the statement in a
modifier.  On the other hand

print "Starting analysis\n" if $verbose;

is better than

$verbose && print "Starting analysis\n";

because the main point isn't whether the user typed B<-v> or not.

Similarly, just because an operator lets you assume default arguments
doesn't mean that you have to make use of the defaults.  The defaults
are there for lazy systems programmers writing one-shot programs.  If
you want your program to be readable, consider supplying the argument.

Along the same lines, just because you I<CAN> omit parentheses in many
places doesn't mean that you ought to:

return print reverse sort num values %array;
    return print(reverse(sort num (values(%array))));

When in doubt, parenthesize.  At the very least it will let some poor
schmuck bounce on the % key in B<vi>.

Even if you aren't in doubt, consider the mental welfare of the person
who has to maintain the code after you, and who will probably put
parentheses in the wrong place.

=item *

Don't go through silly contortions to exit a loop at the top or the
bottom, when Perl provides the C<last> operator so you can exit in
the middle.  Just "outdent" it a little to make it more visible:

LINE:
	for (;;) {
	    statements;
	  last LINE if $foo;
	    next LINE if /^#/;
	    statements;
	}

=item *

Don't be afraid to use loop labels--they're there to enhance
readability as well as to allow multilevel loop breaks.  See the
previous example.

=item *

Avoid using C<grep()> (or C<map()>) or `backticks` in a void context, that is,
when you just throw away their return values.  Those functions all
have return values, so use them.  Otherwise use a C<foreach()> loop or
the C<system()> function instead.

=item *

For portability, when using features that may not be implemented on
every machine, test the construct in an eval to see if it fails.  If
you know what version or patchlevel a particular feature was
implemented, you can test C<$]> (C<$PERL_VERSION> in C<English>) to see if it
will be there.  The C<Config> module will also let you interrogate values
determined by the B<Configure> program when Perl was installed.

=item *

Choose mnemonic identifiers.  If you can't remember what mnemonic means,
you've got a problem.

=item *

While short identifiers like C<$gotit> are probably ok, use underscores to
separate words in longer identifiers.  It is generally easier to read
C<$var_names_like_this> than C<$VarNamesLikeThis>, especially for
non-native speakers of English. It's also a simple rule that works
consistently with C<VAR_NAMES_LIKE_THIS>.

Package names are sometimes an exception to this rule.  Perl informally
reserves lowercase module names for "pragma" modules like C<integer> and
C<strict>.  Other modules should begin with a capital letter and use mixed
case, but probably without underscores due to limitations in primitive
file systems' representations of module names as files that must fit into a
few sparse bytes.

=item *

You may find it helpful to use letter case to indicate the scope
or nature of a variable. For example:

$ALL_CAPS_HERE   constants only (beware clashes with perl vars!)
    $Some_Caps_Here  package-wide global/static
    $no_caps_here    function scope my() or local() variables

Function and method names seem to work best as all lowercase.
E.g., C<$obj-E<gt>as_string()>.

You can use a leading underscore to indicate that a variable or
function should not be used outside the package that defined it.

=item *

If you have a really hairy regular expression, use the C</x> modifier and
put in some whitespace to make it look a little less like line noise.
Don't use slash as a delimiter when your regexp has slashes or backslashes.

=item *

Use the new C<and> and C<or> operators to avoid having to parenthesize
list operators so much, and to reduce the incidence of punctuation
operators like C<&&> and C<||>.  Call your subroutines as if they were
functions or list operators to avoid excessive ampersands and parentheses.

=item *

Use here documents instead of repeated C<print()> statements.

=item *

Line up corresponding things vertically, especially if it'd be too long
to fit on one line anyway.

$IDX = $ST_MTIME;
    $IDX = $ST_ATIME 	   if $opt_u;
    $IDX = $ST_CTIME 	   if $opt_c;
    $IDX = $ST_SIZE  	   if $opt_s;

mkdir $tmpdir, 0700	or die "can't mkdir $tmpdir: $!";
    chdir($tmpdir)      or die "can't chdir $tmpdir: $!";
    mkdir 'tmp',   0777	or die "can't mkdir $tmpdir/tmp: $!";

=item *

Always check the return codes of system calls.  Good error messages should
go to C<STDERR>, include which program caused the problem, what the failed
system call and arguments were, and (VERY IMPORTANT) should contain the
standard system error message for what went wrong.  Here's a simple but
sufficient example:

opendir(D, $dir)	 or die "can't opendir $dir: $!";

=item *

Line up your transliterations when it makes sense:

tr [abc]
       [xyz];

=item *

Think about reusability.  Why waste brainpower on a one-shot when you
might want to do something like it again?  Consider generalizing your
code.  Consider writing a module or object class.  Consider making your
code run cleanly with C<use strict> and C<use warnings> (or B<-w>) in
effect.  Consider giving away your code.  Consider changing your whole
world view.  Consider... oh, never mind.

=item *

Try to document your code and use Pod formatting in a consistent way. Here
are commonly expected conventions:

=over 4

=item *

use C<CE<lt>E<gt>> for function, variable and module names (and more
generally anything that can be considered part of code, like filehandles
or specific values). Note that function names are considered more readable
with parentheses after their name, that is C<function()>.

=item *

use C<BE<lt>E<gt>> for commands names like B<cat> or B<grep>.

=item *

use C<FE<lt>E<gt>> or C<CE<lt>E<gt>> for file names. C<FE<lt>E<gt>> should
be the only Pod code for file names, but as most Pod formatters render it
as italic, Unix and Windows paths with their slashes and backslashes may
be less readable, and better rendered with C<CE<lt>E<gt>>.

=back

=item *

Be consistent.

=item *

Be nice.

=back

=head1 NAME perlstyle - Perl style guide =head1 DESCRIPTION Each programmer will, of course, have his or her own preferences in regards to formatting, but there are some general guidelines that will make your programs easier to read, understand, and maintain. The most important thing is to run your programs under the B<-w> flag at all times. You may turn it off explicitly for particular portions of code via the C pragma or the C<$^W> variable if you must. You should also always run under C or know the reason why not. The C and even C pragmas may also prove useful. Regarding aesthetics of code lay out, about the only thing Larry cares strongly about is that the closing curly bracket of a multi-line BLOCK should line up with the keyword that started the construct. Beyond that, he has other preferences that aren't so strong: =over 4 =item * 4-column indent. =item * Opening curly on same line as keyword, if possible, otherwise line up. =item * Space before the opening curly of a multi-line BLOCK. =item * One-line BLOCK may be put on one line, including curlies. =item * No space before the semicolon. =item * Semicolon omitted in "short" one-line BLOCK. =item * Space around most operators. =item * Space around a "complex" subscript (inside brackets). =item * Blank lines between chunks that do different things. =item * Uncuddled elses. =item * No space between function name and its opening parenthesis. =item * Space after each comma. =item * Long lines broken after an operator (except C and C). =item * Space after last parenthesis matching on current line. =item * Line up corresponding items vertically. =item * Omit redundant punctuation as long as clarity doesn't suffer. =back Larry has his reasons for each of these things, but he doesn't claim that everyone else's mind works the same as his does. Here are some other more substantive style issues to think about: =over 4 =item * Just because you I do something a particular way doesn't mean that you I do it that way. Perl is designed to give you several ways to do anything, so consider picking the most readable one. For instance open(FOO,$foo) || die "Can't open $foo: $!"; is better than die "Can't open $foo: $!" unless open(FOO,$foo); because the second way hides the main point of the statement in a modifier. On the other hand print "Starting analysis\n" if $verbose; is better than $verbose && print "Starting analysis\n"; because the main point isn't whether the user typed B<-v> or not. Similarly, just because an operator lets you assume default arguments doesn't mean that you have to make use of the defaults. The defaults are there for lazy systems programmers writing one-shot programs. If you want your program to be readable, consider supplying the argument. Along the same lines, just because you I omit parentheses in many places doesn't mean that you ought to: return print reverse sort num values %array; return print(reverse(sort num (values(%array)))); When in doubt, parenthesize. At the very least it will let some poor schmuck bounce on the % key in B. Even if you aren't in doubt, consider the mental welfare of the person who has to maintain the code after you, and who will probably put parentheses in the wrong place. =item * Don't go through silly contortions to exit a loop at the top or the bottom, when Perl provides the C operator so you can exit in the middle. Just "outdent" it a little to make it more visible: LINE: for (;;) { statements; last LINE if $foo; next LINE if /^#/; statements; } =item * Don't be afraid to use loop labels--they're there to enhance readability as well as to allow multilevel loop breaks. See the previous example. =item * Avoid using C (or C) or `backticks` in a void context, that is, when you just throw away their return values. Those functions all have return values, so use them. Otherwise use a C loop or the C function instead. =item * For portability, when using features that may not be implemented on every machine, test the construct in an eval to see if it fails. If you know what version or patchlevel a particular feature was implemented, you can test C<$]> (C<$PERL_VERSION> in C) to see if it will be there. The C module will also let you interrogate values determined by the B program when Perl was installed. =item * Choose mnemonic identifiers. If you can't remember what mnemonic means, you've got a problem. =item * While short identifiers like C<$gotit> are probably ok, use underscores to separate words in longer identifiers. It is generally easier to read C<$var_names_like_this> than C<$VarNamesLikeThis>, especially for non-native speakers of English. It's also a simple rule that works consistently with C. Package names are sometimes an exception to this rule. Perl informally reserves lowercase module names for "pragma" modules like C and C. Other modules should begin with a capital letter and use mixed case, but probably without underscores due to limitations in primitive file systems' representations of module names as files that must fit into a few sparse bytes. =item * You may find it helpful to use letter case to indicate the scope or nature of a variable. For example: $ALL_CAPS_HERE constants only (beware clashes with perl vars!) $Some_Caps_Here package-wide global/static $no_caps_here function scope my() or local() variables Function and method names seem to work best as all lowercase. E.g., C<$obj-Eas_string()>. You can use a leading underscore to indicate that a variable or function should not be used outside the package that defined it. =item * If you have a really hairy regular expression, use the C modifier and put in some whitespace to make it look a little less like line noise. Don't use slash as a delimiter when your regexp has slashes or backslashes. =item * Use the new C and C operators to avoid having to parenthesize list operators so much, and to reduce the incidence of punctuation operators like C<&&> and C<||>. Call your subroutines as if they were functions or list operators to avoid excessive ampersands and parentheses. =item * Use here documents instead of repeated C statements. =item * Line up corresponding things vertically, especially if it'd be too long to fit on one line anyway. $IDX = $ST_MTIME; $IDX = $ST_ATIME if $opt_u; $IDX = $ST_CTIME if $opt_c; $IDX = $ST_SIZE if $opt_s; mkdir $tmpdir, 0700 or die "can't mkdir $tmpdir: $!"; chdir($tmpdir) or die "can't chdir $tmpdir: $!"; mkdir 'tmp', 0777 or die "can't mkdir $tmpdir/tmp: $!"; =item * Always check the return codes of system calls. Good error messages should go to C, include which program caused the problem, what the failed system call and arguments were, and (VERY IMPORTANT) should contain the standard system error message for what went wrong. Here's a simple but sufficient example: opendir(D, $dir) or die "can't opendir $dir: $!"; =item * Line up your transliterations when it makes sense: tr [abc] [xyz]; =item * Think about reusability. Why waste brainpower on a one-shot when you might want to do something like it again? Consider generalizing your code. Consider writing a module or object class. Consider making your code run cleanly with C and C (or B<-w>) in effect. Consider giving away your code. Consider changing your whole world view. Consider... oh, never mind. =item * Try to document your code and use Pod formatting in a consistent way. Here are commonly expected conventions: =over 4 =item * use CE> for function, variable and module names (and more generally anything that can be considered part of code, like filehandles or specific values). Note that function names are considered more readable with parentheses after their name, that is C. =item * use CE> for commands names like B or B. =item * use CE> or CE> for file names. CE> should be the only Pod code for file names, but as most Pod formatters render it as italic, Unix and Windows paths with their slashes and backslashes may be less readable, and better rendered with CE>. =back =item * Be consistent. =item * Be nice. =back