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author | Father Chrysostomos <sprout@cpan.org> | 2012-01-05 09:43:31 -0800 |
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committer | Father Chrysostomos <sprout@cpan.org> | 2012-01-05 14:29:47 -0800 |
commit | 391b733c974402fd42daeb08734cbd7432c8149b (patch) | |
tree | b6ddcbdd912feb6ed4add8758b35dc3c1bc1a3ca /pod/perlfunc.pod | |
parent | d247f55d9964271eaec6d9df9c3f99778c11443f (diff) | |
download | perl-391b733c974402fd42daeb08734cbd7432c8149b.tar.gz |
perlfunc: spaces after dots
Diffstat (limited to 'pod/perlfunc.pod')
-rw-r--r-- | pod/perlfunc.pod | 235 |
1 files changed, 123 insertions, 112 deletions
diff --git a/pod/perlfunc.pod b/pod/perlfunc.pod index f9bfcb22e9..160352eada 100644 --- a/pod/perlfunc.pod +++ b/pod/perlfunc.pod @@ -185,7 +185,7 @@ other keywords. C<caller>, C<import>, C<local>, C<my>, C<our>, C<package>, C<state>, C<use> C<state> is available only if the C<"state"> feature -is enabled or if it is prefixed with C<CORE::>. See +is enabled or if it is prefixed with C<CORE::>. See L<feature>. Alternately, include a C<use v5.10> or later to the current scope. =item Miscellaneous functions @@ -397,7 +397,7 @@ test whether the permission can(not) be granted using the access(2) family of system calls. Also note that the C<-x> and C<-X> may under this pragma return true even if there are no execute permission bits set (nor any extra execute permission ACLs). This strangeness is -due to the underlying system calls' definitions. Note also that, due to +due to the underlying system calls' definitions. Note also that, due to the implementation of C<use filetest 'access'>, the C<_> special filehandle won't cache the results of the file tests when this pragma is in effect. Read the documentation for the C<filetest> pragma for more @@ -437,7 +437,7 @@ Example: As of Perl 5.9.1, as a form of purely syntactic sugar, you can stack file test operators, in a way that C<-f -w -x $file> is equivalent to -C<-x $file && -w _ && -f _>. (This is only fancy fancy: if you use +C<-x $file && -w _ && -f _>. (This is only fancy fancy: if you use the return value of C<-f $file> as an argument to another filetest operator, no special magic will happen.) @@ -476,7 +476,7 @@ X<timer> Arranges to have a SIGALRM delivered to this process after the specified number of wallclock seconds has elapsed. If SECONDS is not -specified, the value stored in C<$_> is used. (On some machines, +specified, the value stored in C<$_> is used. (On some machines, unfortunately, the elapsed time may be up to one second less or more than you specified because of how seconds are counted, and process scheduling may delay the delivery of the signal even further.) @@ -491,7 +491,7 @@ For delays of finer granularity than one second, the Time::HiRes module distribution) provides ualarm(). You may also use Perl's four-argument version of select() leaving the first three arguments undefined, or you might be able to use the C<syscall> interface to access setitimer(2) if -your system supports it. See L<perlfaq8> for details. +your system supports it. See L<perlfaq8> for details. It is usually a mistake to intermix C<alarm> and C<sleep> calls, because C<sleep> may be internally implemented on your system with C<alarm>. @@ -564,16 +564,16 @@ In other words: regardless of platform, use binmode() on binary data, like images, for example. If LAYER is present it is a single string, but may contain multiple -directives. The directives alter the behaviour of the filehandle. +directives. The directives alter the behaviour of the filehandle. When LAYER is present, using binmode on a text file makes sense. If LAYER is omitted or specified as C<:raw> the filehandle is made -suitable for passing binary data. This includes turning off possible CRLF +suitable for passing binary data. This includes turning off possible CRLF translation and marking it as bytes (as opposed to Unicode characters). Note that, despite what may be implied in I<"Programming Perl"> (the Camel, 3rd edition) or elsewhere, C<:raw> is I<not> simply the inverse of C<:crlf>. Other layers that would affect the binary nature of the stream are -I<also> disabled. See L<PerlIO>, L<perlrun>, and the discussion about the +I<also> disabled. See L<PerlIO>, L<perlrun>, and the discussion about the PERLIO environment variable. The C<:bytes>, C<:crlf>, C<:utf8>, and any other directives of the @@ -590,7 +590,7 @@ of this version of Perl therefore refers to "layers" rather than to To mark FILEHANDLE as UTF-8, use C<:utf8> or C<:encoding(UTF-8)>. C<:utf8> just marks the data as UTF-8 without further checking, while C<:encoding(UTF-8)> checks the data for actually being valid -UTF-8. More details can be found in L<PerlIO::encoding>. +UTF-8. More details can be found in L<PerlIO::encoding>. In general, binmode() should be called after open() but before any I/O is done on the filehandle. Calling binmode() normally flushes any @@ -613,7 +613,7 @@ one character. All variants of Unix, Mac OS (old and new), and Stream_LF files on VMS use a single character to end each line in the external representation of text (even though that single character is CARRIAGE RETURN on old, pre-Darwin -flavors of Mac OS, and is LINE FEED on Unix and most VMS files). In other +flavors of Mac OS, and is LINE FEED on Unix and most VMS files). In other systems like OS/2, DOS, and the various flavors of MS-Windows, your program sees a C<\n> as a simple C<\cJ>, but what's stored in text files are the two characters C<\cM\cJ>. That means that if you don't use binmode() on @@ -650,7 +650,7 @@ SeeL<perlobj> for more about the blessing (and blessings) of objects. Consider always blessing objects in CLASSNAMEs that are mixed case. Namespaces with all lowercase names are considered reserved for -Perl pragmata. Builtin types have all uppercase names. To prevent +Perl pragmata. Builtin types have all uppercase names. To prevent confusion, you may wish to avoid such package names as well. Make sure that CLASSNAME is a true value. @@ -704,7 +704,7 @@ compiled with. The C<$hints> and C<$bitmask> values are subject to change between versions of Perl, and are not meant for external use. C<$hinthash> is a reference to a hash containing the value of C<%^H> when the -caller was compiled, or C<undef> if C<%^H> was empty. Do not modify the values +caller was compiled, or C<undef> if C<%^H> was empty. Do not modify the values of this hash, as they are the actual values stored in the optree. Furthermore, when called from within the DB package in @@ -719,18 +719,18 @@ C<< N > 1 >>. In particular, C<@DB::args> might have information from the previous time C<caller> was called. Be aware that setting C<@DB::args> is I<best effort>, intended for -debugging or generating backtraces, and should not be relied upon. In +debugging or generating backtraces, and should not be relied upon. In particular, as C<@_> contains aliases to the caller's arguments, Perl does not take a copy of C<@_>, so C<@DB::args> will contain modifications the subroutine makes to C<@_> or its contents, not the original values at call -time. C<@DB::args>, like C<@_>, does not hold explicit references to its +time. C<@DB::args>, like C<@_>, does not hold explicit references to its elements, so under certain cases its elements may have become freed and -reallocated for other variables or temporary values. Finally, a side effect +reallocated for other variables or temporary values. Finally, a side effect of the current implementation is that the effects of C<shift @_> can I<normally> be undone (but not C<pop @_> or other splicing, I<and> not if a reference to C<@_> has been taken, I<and> subject to the caveat about reallocated elements), so C<@DB::args> is actually a hybrid of the current state and -initial state of C<@_>. Buyer beware. +initial state of C<@_>. Buyer beware. =item chdir EXPR X<chdir> @@ -743,12 +743,12 @@ X<directory, change> =item chdir -Changes the working directory to EXPR, if possible. If EXPR is omitted, +Changes the working directory to EXPR, if possible. If EXPR is omitted, changes to the directory specified by C<$ENV{HOME}>, if set; if not, -changes to the directory specified by C<$ENV{LOGDIR}>. (Under VMS, the -variable C<$ENV{SYS$LOGIN}> is also checked, and used if it is set.) If -neither is set, C<chdir> does nothing. It returns true on success, -false otherwise. See the example under C<die>. +changes to the directory specified by C<$ENV{LOGDIR}>. (Under VMS, the +variable C<$ENV{SYS$LOGIN}> is also checked, and used if it is set.) If +neither is set, C<chdir> does nothing. It returns true on success, +false otherwise. See the example under C<die>. On systems that support fchdir(2), you may pass a filehandle or directory handle as the argument. On systems that don't support fchdir(2), @@ -1080,7 +1080,7 @@ of SALT may matter. Traditionally the result is a string of 13 bytes: two first bytes of the salt, followed by 11 bytes from the set C<[./0-9A-Za-z]>, and only -the first eight bytes of PLAINTEXT mattered. But alternative +the first eight bytes of PLAINTEXT mattered. But alternative hashing schemes (like MD5), higher level security schemes (like C2), and implementations on non-Unix platforms may produce different strings. @@ -1327,10 +1327,10 @@ final operation is an element or slice of an aggregate: =item die LIST X<die> X<throw> X<exception> X<raise> X<$@> X<abort> -C<die> raises an exception. Inside an C<eval> the error message is stuffed +C<die> raises an exception. Inside an C<eval> the error message is stuffed into C<$@> and the C<eval> is terminated with the undefined value. If the exception is outside of all enclosing C<eval>s, then the uncaught -exception prints LIST to C<STDERR> and exits with a non-zero value. If you +exception prints LIST to C<STDERR> and exits with a non-zero value. If you need to exit the process with a specific exit code, see L</exit>. Equivalent examples: @@ -1380,7 +1380,8 @@ determined from the values of C<$!> and C<$?> with this pseudocode: exit 255; # last resort The intent is to squeeze as much possible information about the likely cause -into the limited space of the system exit code. However, as C<$!> is the value +into the limited space of the system exit +code. However, as C<$!> is the value of C's C<errno>, which can be set by any system call, this means that the value of the exit code used by C<die> can be non-predictable, so should not be relied upon, other than to be non-zero. @@ -1436,7 +1437,7 @@ X<do> X<block> Not really a function. Returns the value of the last command in the sequence of commands indicated by BLOCK. When modified by the C<while> or C<until> loop modifier, executes the BLOCK once before testing the loop -condition. (On other statements the loop modifiers test the conditional +condition. (On other statements the loop modifiers test the conditional first.) C<do BLOCK> does I<not> count as a loop, so the loop control statements @@ -1513,7 +1514,7 @@ be open any more when the program is reincarnated, with possible resulting confusion by Perl. This function is now largely obsolete, mostly because it's very hard to -convert a core file into an executable. That's why you should now invoke +convert a core file into an executable. That's why you should now invoke it as C<CORE::dump()>, if you don't want to be warned against a possible typo. @@ -1977,7 +1978,7 @@ The exit() function does not always exit immediately. It calls any defined C<END> routines first, but these C<END> routines may not themselves abort the exit. Likewise any object destructors that need to be called are called before the real exit. C<END> routines and destructors -can change the exit status by modifying C<$?>. If this is a problem, you +can change the exit status by modifying C<$?>. If this is a problem, you can call C<POSIX:_exit($status)> to avoid END and destructor processing. See L<perlmod> for details. @@ -2167,8 +2168,9 @@ backgrounded job launched from a remote shell) won't think you're done. You should reopen those to F</dev/null> if it's any issue. On some platforms such as Windows, where the fork() system call is not available, -Perl can be built to emulate fork() in the Perl interpreter. The emulation is designed to, -at the level of the Perl program, be as compatible as possible with the "Unix" fork(). +Perl can be built to emulate fork() in the Perl interpreter. +The emulation is designed, at the level of the Perl program, +to be as compatible as possible with the "Unix" fork(). However it has limitations that have to be considered in code intended to be portable. See L<perlfork> for more details. @@ -2297,9 +2299,9 @@ X<getppid> X<parent> X<pid> Returns the process id of the parent process. Note for Linux users: on Linux, the C functions C<getpid()> and -C<getppid()> return different values from different threads. In order to +C<getppid()> return different values from different threads. In order to be portable, this behavior is not reflected by the Perl-level function -C<getppid()>, that returns a consistent value across threads. If you want +C<getppid()>, that returns a consistent value across threads. If you want to call the underlying C<getppid()>, you may use the CPAN module C<Linux::Pid>. @@ -2514,15 +2516,15 @@ X<getsockopt> Queries the option named OPTNAME associated with SOCKET at a given LEVEL. Options may exist at multiple protocol levels depending on the socket type, but at least the uppermost socket level SOL_SOCKET (defined in the -C<Socket> module) will exist. To query options at another level the +C<Socket> module) will exist. To query options at another level the protocol number of the appropriate protocol controlling the option -should be supplied. For example, to indicate that an option is to be +should be supplied. For example, to indicate that an option is to be interpreted by the TCP protocol, LEVEL should be set to the protocol number of TCP, which you can get using C<getprotobyname>. The function returns a packed string representing the requested socket option, or C<undef> on error, with the reason for the error placed in -C<$!>. Just what is in the packed string depends on LEVEL and OPTNAME; +C<$!>. Just what is in the packed string depends on LEVEL and OPTNAME; consult getsockopt(2) for details. A common case is that the option is an integer, in which case the result is a packed integer, which you can decode using C<unpack> with the C<i> (or C<I>) format. @@ -2546,7 +2548,8 @@ X<given> =item given BLOCK -C<given> is analogous to the C<switch> keyword in other languages. C<given> +C<given> is analogous to the C<switch> +keyword in other languages. C<given> and C<when> are used in Perl to implement C<switch>/C<case> like statements. Only available after Perl 5.10. For example: @@ -2571,10 +2574,10 @@ X<glob> X<wildcard> X<filename, expansion> X<expand> =item glob In list context, returns a (possibly empty) list of filename expansions on -the value of EXPR such as the standard Unix shell F</bin/csh> would do. In +the value of EXPR such as the standard Unix shell F</bin/csh> would do. In scalar context, glob iterates through such filename expansions, returning -undef when the list is exhausted. This is the internal function -implementing the C<< <*.c> >> operator, but you can use it directly. If +undef when the list is exhausted. This is the internal function +implementing the C<< <*.c> >> operator, but you can use it directly. If EXPR is omitted, C<$_> is used. The C<< <*.c> >> operator is discussed in more detail in L<perlop/"I/O Operators">. @@ -2631,7 +2634,7 @@ X<goto> X<jump> X<jmp> =item goto &NAME The C<goto-LABEL> form finds the statement labeled with LABEL and -resumes execution there. It can't be used to get out of a block or +resumes execution there. It can't be used to get out of a block or subroutine given to C<sort>. It can be used to go almost anywhere else within the dynamic scope, including out of subroutines, but it's usually better to use some other construct such as C<last> or C<die>. @@ -2647,8 +2650,8 @@ necessarily recommended if you're optimizing for maintainability: goto ("FOO", "BAR", "GLARCH")[$i]; As shown in this example, C<goto-EXPR> is exempt from the "looks like a -function" rule. A pair of parentheses following it does not (necessarily) -delimit its argument. C<goto("NE")."XT"> is equivalent to C<goto NEXT>. +function" rule. A pair of parentheses following it does not (necessarily) +delimit its argument. C<goto("NE")."XT"> is equivalent to C<goto NEXT>. Use of C<goto-LABEL> or C<goto-EXPR> to jump into a construct is deprecated and will issue a warning. Even then, it may not be used to @@ -2721,7 +2724,7 @@ L</oct>.) If EXPR is omitted, uses C<$_>. Hex strings may only represent integers. Strings that would cause integer overflow trigger a warning. Leading whitespace is not stripped, -unlike oct(). To present something as hex, look into L</printf>, +unlike oct(). To present something as hex, look into L</printf>, L</sprintf>, and L</unpack>. =item import LIST @@ -2912,7 +2915,8 @@ alive (even if only as a zombie) and hasn't changed its UID. See L<perlport> for notes on the portability of this construct. Unlike in the shell, if SIGNAL is negative, it kills process groups instead -of processes. That means you usually want to use positive not negative signals. +of processes. That means you usually +want to use positive not negative signals. You may also use a signal name in quotes. The behavior of kill when a I<PROCESS> number is zero or negative depends on @@ -3151,8 +3155,9 @@ In scalar context, C<localtime()> returns the ctime(3) value: $now_string = localtime; # e.g., "Thu Oct 13 04:54:34 1994" -This scalar value is B<not> locale-dependent but is a Perl builtin. For GMT -instead of local time use the L</gmtime> builtin. See also the +The format of this scalar value is B<not> locale-dependent +but built into Perl. For GMT instead of local +time use the L</gmtime> builtin. See also the C<Time::Local> module (for converting seconds, minutes, hours, and such back to the integer value returned by time()), and the L<POSIX> module's strftime(3) and mktime(3) functions. @@ -3256,7 +3261,7 @@ translates a list of numbers to their squared values. my @squares = map { $_ > 5 ? ($_ * $_) : () } @numbers; shows that number of returned elements can differ from the number of -input elements. To omit an element, return an empty list (). +input elements. To omit an element, return an empty list (). This could also be achieved by writing my @squares = map { $_ * $_ } grep { $_ > 5 } @numbers; @@ -3265,7 +3270,7 @@ which makes the intention more clear. Map always returns a list, which can be assigned to a hash such that the elements -become key/value pairs. See L<perldata> for more details. +become key/value pairs. See L<perldata> for more details. %hash = map { get_a_key_for($_) => $_ } @array; @@ -3289,11 +3294,12 @@ the list elements, C<$_> keeps being lexical inside the block; that is, it can't be seen from the outside, avoiding any potential side-effects. C<{> starts both hash references and blocks, so C<map { ...> could be either -the start of map BLOCK LIST or map EXPR, LIST. Because Perl doesn't look +the start of map BLOCK LIST or map EXPR, LIST. Because Perl doesn't look ahead for the closing C<}> it has to take a guess at which it's dealing with -based on what it finds just after the C<{>. Usually it gets it right, but if it +based on what it finds just after the +C<{>. Usually it gets it right, but if it doesn't it won't realize something is wrong until it gets to the C<}> and -encounters the missing (or unexpected) comma. The syntax error will be +encounters the missing (or unexpected) comma. The syntax error will be reported close to the C<}>, but you'll need to change something near the C<{> such as using a unary C<+> to give Perl some help: @@ -3572,13 +3578,13 @@ or C<-> opens STDIN and opening C<< >- >> opens STDOUT. You may (and usually should) use the three-argument form of open to specify I/O layers (sometimes referred to as "disciplines") to apply to the handle that affect how the input and output are processed (see L<open> and -L<PerlIO> for more details). For example: +L<PerlIO> for more details). For example: open(my $fh, "<:encoding(UTF-8)", "filename") || die "can't open UTF-8 encoded filename: $!"; opens the UTF8-encoded file containing Unicode characters; -see L<perluniintro>. Note that if layers are specified in the +see L<perluniintro>. Note that if layers are specified in the three-argument form, then default layers stored in ${^OPEN} (see L<perlvar>; usually set by the B<open> pragma or the switch B<-CioD>) are ignored. Those layers will also be ignored if you specifying a colon with no name @@ -3688,7 +3694,8 @@ duped (as C<dup(2)>) and opened. You may use C<&> after C<< > >>, C<<< >> >>>, C<< < >>, C<< +> >>, C<<< +>> >>>, and C<< +< >>. The mode you specify should match the mode of the original filehandle. (Duping a filehandle does not take into account any existing contents -of IO buffers.) If you use the three-argument form, then you can pass either a +of IO buffers.) If you use the three-argument +form, then you can pass either a number, the name of a filehandle, or the normal "reference to a glob". Here is a script that saves, redirects, and restores C<STDOUT> and @@ -4098,8 +4105,8 @@ TEMPLATE (the second column lists letters for which the modifier is valid): nNvV Treat integers as signed instead of unsigned. @. Specify position as byte offset in the internal - representation of the packed string. Efficient but - dangerous. + representation of the packed string. Efficient + but dangerous. > sSiIlLqQ Force big-endian byte-order on the type. jJfFdDpP (The "big end" touches the construct.) @@ -4181,7 +4188,7 @@ bigger then the group level. =back The repeat count for C<u> is interpreted as the maximal number of bytes -to encode per line of output, with 0, 1 and 2 replaced by 45. The repeat +to encode per line of output, with 0, 1 and 2 replaced by 45. The repeat count should not be more than 65. =item * @@ -4274,18 +4281,18 @@ unpacking has encoded the sizes or repeat counts for some of its fields within the structure itself as separate fields. For C<pack>, you write I<length-item>C</>I<sequence-item>, and the -I<length-item> describes how the length value is packed. Formats likely +I<length-item> describes how the length value is packed. Formats likely to be of most use are integer-packing ones like C<n> for Java strings, C<w> for ASN.1 or SNMP, and C<N> for Sun XDR. For C<pack>, I<sequence-item> may have a repeat count, in which case the minimum of that and the number of available items is used as the argument -for I<length-item>. If it has no repeat count or uses a '*', the number +for I<length-item>. If it has no repeat count or uses a '*', the number of available items is used. For C<unpack>, an internal stack of integer arguments unpacked so far is -used. You write C</>I<sequence-item> and the repeat count is obtained by -popping off the last element from the stack. The I<sequence-item> must not +used. You write C</>I<sequence-item> and the repeat count is obtained by +popping off the last element from the stack. The I<sequence-item> must not have a repeat count. If I<sequence-item> refers to a string type (C<"A">, C<"a">, or C<"Z">), @@ -4465,8 +4472,9 @@ will not in general equal $foo. Pack and unpack can operate in two modes: character mode (C<C0> mode) where the packed string is processed per character, and UTF-8 mode (C<U0> mode) where the packed string is processed in its UTF-8-encoded Unicode form on -a byte-by-byte basis. Character mode is the default unless the format string -starts with C<U>. You can always switch mode mid-format with an explicit +a byte-by-byte basis. Character mode is the default +unless the format string starts with C<U>. You +can always switch mode mid-format with an explicit C<C0> or C<U0> in the format. This mode remains in effect until the next mode change, or until the end of the C<()> group it (directly) applies to. @@ -4502,7 +4510,7 @@ handle their output and input as flat sequences of characters. A C<()> group is a sub-TEMPLATE enclosed in parentheses. A group may take a repeat count either as postfix, or for unpack(), also via the C</> template character. Within each repetition of a group, positioning with -C<@> starts over at 0. Therefore, the result of +C<@> starts over at 0. Therefore, the result of pack("@1A((@2A)@3A)", qw[X Y Z]) @@ -4512,7 +4520,7 @@ is the string C<"\0X\0\0YZ">. C<x> and C<X> accept the C<!> modifier to act as alignment commands: they jump forward or back to the closest position aligned at a multiple of C<count> -characters. For example, to pack() or unpack() a C structure like +characters. For example, to pack() or unpack() a C structure like struct { char c; /* one signed, 8-bit character */ @@ -4560,7 +4568,7 @@ Examples: $foo = pack("W4",0x24b6,0x24b7,0x24b8,0x24b9); # same thing with Unicode circled letters. $foo = pack("U4",0x24b6,0x24b7,0x24b8,0x24b9); - # same thing with Unicode circled letters. You don't get the + # same thing with Unicode circled letters. You don't get the # UTF-8 bytes because the U at the start of the format caused # a switch to U0-mode, so the UTF-8 bytes get joined into # characters @@ -4722,14 +4730,14 @@ X<pos> X<match, position> Returns the offset of where the last C<m//g> search left off for the variable in question (C<$_> is used when the variable is not -specified). Note that 0 is a valid match offset. C<undef> indicates +specified). Note that 0 is a valid match offset. C<undef> indicates that the search position is reset (usually due to match failure, but can also be because no match has yet been run on the scalar). C<pos> directly accesses the location used by the regexp engine to store the offset, so assigning to C<pos> will change that offset, and so will also influence the C<\G> zero-width assertion in regular -expressions. Both of these effects take place for the next match, so +expressions. Both of these effects take place for the next match, so you can't affect the position with C<pos> during the current match, such as in C<(?{pos() = 5})> or C<s//pos() = 5/e>. @@ -4754,7 +4762,7 @@ FILEHANDLE may be a scalar variable containing the name of or a reference to the filehandle, thus introducing one level of indirection. (NOTE: If FILEHANDLE is a variable and the next token is a term, it may be misinterpreted as an operator unless you interpose a C<+> or put -parentheses around the arguments.) If FILEHANDLE is omitted, prints to the +parentheses around the arguments.) If FILEHANDLE is omitted, prints to the last selected (see L</select>) output handle. If LIST is omitted, prints C<$_> to the currently selected output handle. To use FILEHANDLE alone to print the content of C<$_> to it, you must use a real filehandle like @@ -4793,9 +4801,9 @@ X<printf> Equivalent to C<print FILEHANDLE sprintf(FORMAT, LIST)>, except that C<$\> (the output record separator) is not appended. The first argument of the -list will be interpreted as the C<printf> format. See +list will be interpreted as the C<printf> format. See L<sprintf|/sprintf FORMAT, LIST> for an -explanation of the format argument. If you omit the LIST, C<$_> is used; +explanation of the format argument. If you omit the LIST, C<$_> is used; to use FILEHANDLE without a LIST, you must use a real filehandle like C<FH>, not an indirect one like C<$fh>. If C<use locale> is in effect and POSIX::setlocale() has been called, the character used for the decimal @@ -4878,7 +4886,7 @@ If EXPR is omitted, uses C<$_>. quotemeta (and C<\Q> ... C<\E>) are useful when interpolating strings into regular expressions, because by default an interpolated variable will be -considered a mini-regular expression. For example: +considered a mini-regular expression. For example: my $sentence = 'The quick brown fox jumped over the lazy dog'; my $substring = 'quick.*?fox'; @@ -4899,7 +4907,8 @@ Or: my $quoted_substring = quotemeta($substring); $sentence =~ s{$quoted_substring}{big bad wolf}; -Will both leave the sentence as is. Normally, when accepting literal string +Will both leave the sentence as is. +Normally, when accepting literal string input from the user, quotemeta() or C<\Q> must be used. In Perl 5.14, all characters whose code points are above 127 are not @@ -5036,7 +5045,7 @@ C<readline> and dies if the result is not defined. } Note that you have can't handle C<readline> errors that way with the -C<ARGV> filehandle. In that case, you have to open each element of +C<ARGV> filehandle. In that case, you have to open each element of C<@ARGV> yourself since C<eof> handles C<ARGV> differently. foreach my $arg (@ARGV) { @@ -5141,7 +5150,7 @@ X<ref> X<reference> =item ref Returns a non-empty string if EXPR is a reference, the empty -string otherwise. If EXPR +string otherwise. If EXPR is not specified, C<$_> will be used. The value returned depends on the type of thing the reference is a reference to. Builtin types include: @@ -5169,8 +5178,8 @@ name is returned instead. You can think of C<ref> as a C<typeof> operator. } The return value C<LVALUE> indicates a reference to an lvalue that is not -a variable. You get this from taking the reference of function calls like -C<pos()> or C<substr()>. C<VSTRING> is returned if the reference points +a variable. You get this from taking the reference of function calls like +C<pos()> or C<substr()>. C<VSTRING> is returned if the reference points to a L<version string|perldata/"Version Strings">. The result C<Regexp> indicates that the argument is a regular expression @@ -5292,7 +5301,7 @@ will complain about not finding "F<Foo::Bar>" there. In this case you can do: Now that you understand how C<require> looks for files with a bareword argument, there is a little extra functionality going on behind the scenes. Before C<require> looks for a "F<.pm>" extension, it will -first look for a similar filename with a "F<.pmc>" extension. If this file +first look for a similar filename with a "F<.pmc>" extension. If this file is found, it will be loaded in place of any file ending in a "F<.pm>" extension. @@ -5315,7 +5324,7 @@ A filehandle, from which the file will be read. =item 2 -A reference to a subroutine. If there is no filehandle (previous item), +A reference to a subroutine. If there is no filehandle (previous item), then this subroutine is expected to generate one line of source code per call, writing the line into C<$_> and returning 1, then finally at end of file returning 0. If there is a filehandle, then the subroutine will be @@ -5325,7 +5334,7 @@ returned. =item 3 -Optional state for the subroutine. The state is passed in as C<$_[1]>. A +Optional state for the subroutine. The state is passed in as C<$_[1]>. A reference to the subroutine itself is passed in as C<$_[0]>. =back @@ -5376,7 +5385,7 @@ into package C<main>.) Here is a typical code layout: push @INC, Foo->new(...); These hooks are also permitted to set the %INC entry -corresponding to the files they have loaded. See L<perlvar/%INC>. +corresponding to the files they have loaded. See L<perlvar/%INC>. For a yet-more-powerful import facility, see L</use> and L<perlmod>. @@ -5673,8 +5682,8 @@ On error, C<select> behaves just like select(2): it returns On some Unixes, select(2) may report a socket file descriptor as "ready for reading" even when no data is available, and thus any subsequent C<read> -would block. This can be avoided if you always use O_NONBLOCK on the -socket. See select(2) and fcntl(2) for further details. +would block. This can be avoided if you always use O_NONBLOCK on the +socket. See select(2) and fcntl(2) for further details. The standard C<IO::Select> module provides a user-friendlier interface to C<select>, mostly because it does all the bit-mask work for you. @@ -5857,7 +5866,7 @@ detaching from it. When reading, VAR must be a variable that will hold the data read. When writing, if STRING is too long, only SIZE bytes are used; if STRING is too short, nulls are written to fill out SIZE bytes. Return true if successful, false on error. -shmread() taints the variable. See also L<perlipc/"SysV IPC">, +shmread() taints the variable. See also L<perlipc/"SysV IPC">, C<IPC::SysV>, and the C<IPC::Shareable> module from CPAN. Portability issues: L<perlport/shmread> and L<perlport/shmwrite>. @@ -5925,7 +5934,7 @@ For delays of finer granularity than one second, the Time::HiRes module distribution) provides usleep(). You may also use Perl's four-argument version of select() leaving the first three arguments undefined, or you might be able to use the C<syscall> interface to access setitimer(2) if -your system supports it. See L<perlfaq8> for details. +your system supports it. See L<perlfaq8> for details. See also the POSIX module's C<pause> function. @@ -6118,7 +6127,7 @@ Examples: @new = sort { substr($a, 3, 5) cmp substr($b, 3, 5) } @old; Warning: syntactical care is required when sorting the list returned from -a function. If you want to sort the list returned by the function call +a function. If you want to sort the list returned by the function call C<find_records(@key)>, you can use: @contact = sort { $a cmp $b } find_records @key; @@ -6176,7 +6185,7 @@ If OFFSET is negative then it starts that far from the end of the array. If LENGTH is omitted, removes everything from OFFSET onward. If LENGTH is negative, removes the elements from OFFSET onward except for -LENGTH elements at the end of the array. -If both OFFSET and LENGTH are omitted, removes everything. If OFFSET is +If both OFFSET and LENGTH are omitted, removes everything. If OFFSET is past the end of the array, Perl issues a warning, and splices at the end of the array. @@ -6263,11 +6272,11 @@ produces the output 'h:i: :t:h:e:r:e'. Empty leading fields are produced when there are positive-width matches at the beginning of the string; a zero-width match at the beginning of -the string does not produce an empty field. For example: +the string does not produce an empty field. For example: print join(':', split(/(?=\w)/, 'hi there!')); -produces the output 'h:i :t:h:e:r:e!'. Empty trailing fields, on the other +produces the output 'h:i :t:h:e:r:e!'. Empty trailing fields, on the other hand, are produced when there is a match at the end of the string (and when LIMIT is given and is not 0), regardless of the length of the match. For example: @@ -6357,7 +6366,8 @@ Non-standard extensions in your local sprintf(3) are therefore unavailable from Perl. Unlike C<printf>, C<sprintf> does not do what you probably mean when you -pass it an array as your first argument. The array is given scalar context, +pass it an array as your first argument. +The array is given scalar context, and instead of using the 0th element of the array as the format, Perl will use the count of elements in the array as the format, which is almost never useful. @@ -6409,7 +6419,7 @@ In order, these are: =item format parameter index -An explicit format parameter index, such as C<2$>. By default sprintf +An explicit format parameter index, such as C<2$>. By default sprintf will format the next unused argument in the list, but this allows you to take the arguments out of order: @@ -6457,9 +6467,9 @@ the precision is incremented if it's necessary for the leading "0". =item vector flag This flag tells Perl to interpret the supplied string as a vector of -integers, one for each character in the string. Perl applies the format to +integers, one for each character in the string. Perl applies the format to each integer in turn, then joins the resulting strings with a separator (a -dot C<.> by default). This can be useful for displaying ordinal values of +dot C<.> by default). This can be useful for displaying ordinal values of characters in arbitrary strings: printf "%vd", "AB\x{100}"; # prints "65.66.256" @@ -6479,7 +6489,7 @@ the join string using something like C<*2$v>; for example: =item (minimum) width Arguments are usually formatted to be only as wide as required to -display the given value. You can override the width by putting +display the given value. You can override the width by putting a number here, or get the width from the next argument (with C<*>) or from a specified argument (e.g., with C<*2$>): @@ -6571,7 +6581,7 @@ example using C<.*2$>: =item size For numeric conversions, you can specify the size to interpret the -number as using C<l>, C<h>, C<V>, C<q>, C<L>, or C<ll>. For integer +number as using C<l>, C<h>, C<V>, C<q>, C<L>, or C<ll>. For integer conversions (C<d u o x X b i D U O>), numbers are usually assumed to be whatever the default integer size is on your platform (usually 32 or 64 bits), but you can override this to use instead one of the standard C types, @@ -6610,7 +6620,7 @@ You can find out whether your Perl supports quads via L<Config>: For floating-point conversions (C<e f g E F G>), numbers are usually assumed to be the default floating-point size on your platform (double or long double), but you can force "long double" with C<q>, C<L>, or C<ll> if your -platform supports them. You can find out whether your Perl supports long +platform supports them. You can find out whether your Perl supports long doubles via L<Config>: use Config; @@ -6637,7 +6647,7 @@ integer or floating-point number", which is the default. =item order of arguments Normally, sprintf() takes the next unused argument as the value to -format for each format specification. If the format specification +format for each format specification. If the format specification uses C<*> to require additional arguments, these are consumed from the argument list in the order they appear in the format specification I<before> the value to format. Where an argument is @@ -6787,7 +6797,7 @@ meanings of the fields: (The epoch was at 00:00 January 1, 1970 GMT.) -(*) Not all fields are supported on all filesystem types. Notably, the +(*) Not all fields are supported on all filesystem types. Notably, the ctime field is non-portable. In particular, you cannot expect it to be a "creation time"; see L<perlport/"Files and Filesystems"> for details. @@ -7123,7 +7133,7 @@ X<sysopen> Opens the file whose filename is given by FILENAME, and associates it with FILEHANDLE. If FILEHANDLE is an expression, its value is used as the real -filehandle wanted; an undefined scalar will be suitably autovivified. This +filehandle wanted; an undefined scalar will be suitably autovivified. This function calls the underlying operating system's I<open>(2) function with the parameters FILENAME, MODE, and PERMS. @@ -7173,7 +7183,7 @@ on this. Note that C<sysopen> depends on the fdopen() C library function. On many Unix systems, fdopen() is known to fail when file descriptors -exceed a certain value, typically 255. If you need more file +exceed a certain value, typically 255. If you need more file descriptors than that, consider rebuilding Perl to use the C<sfio> library, or perhaps using the POSIX::open() function. @@ -7271,7 +7281,7 @@ of C<IO::Handle> on any open handles. The return value is the exit status of the program as returned by the C<wait> call. To get the actual exit value, shift right by eight (see -below). See also L</exec>. This is I<not> what you want to use to capture +below). See also L</exec>. This is I<not> what you want to use to capture the output from a command; for that you should use merely backticks or C<qx//>, as described in L<perlop/"`STRING`">. Return value of -1 indicates a failure to start the program or an error of the wait(2) system @@ -7314,7 +7324,7 @@ results and return codes are subject to its quirks. See L<perlop/"`STRING`"> and L</exec> for details. Since C<system> does a C<fork> and C<wait> it may affect a C<SIGCHLD> -handler. See L<perlipc> for details. +handler. See L<perlipc> for details. Portability issues: L<perlport/system>. @@ -7487,7 +7497,7 @@ X<time> X<epoch> Returns the number of non-leap seconds since whatever time the system considers to be the epoch, suitable for feeding to C<gmtime> and -C<localtime>. On most systems the epoch is 00:00:00 UTC, January 1, 1970; +C<localtime>. On most systems the epoch is 00:00:00 UTC, January 1, 1970; a prominent exception being Mac OS Classic which uses 00:00:00, January 1, 1904 in the current local time zone for its epoch. @@ -7637,8 +7647,8 @@ X<unlink> X<delete> X<remove> X<rm> X<del> =item unlink -Deletes a list of files. On success, it returns the number of files -it successfully deleted. On failure, it returns false and sets C<$!> +Deletes a list of files. On success, it returns the number of files +it successfully deleted. On failure, it returns false and sets C<$!> (errno): my $unlinked = unlink 'a', 'b', 'c'; @@ -7654,7 +7664,7 @@ at a time: } Note: C<unlink> will not attempt to delete directories unless you are -superuser and the B<-U> flag is supplied to Perl. Even if these +superuser and the B<-U> flag is supplied to Perl. Even if these conditions are met, be warned that unlinking a directory can inflict damage on your filesystem. Finally, using C<unlink> on directories is not supported on many operating systems. Use C<rmdir> instead. @@ -7900,7 +7910,7 @@ the user running the program: Since Perl 5.7.2, if the first two elements of the list are C<undef>, the utime(2) syscall from your C library is called with a null second -argument. On most systems, this will set the file's access and +argument. On most systems, this will set the file's access and modification times to the current time (i.e., equivalent to the example above) and will work even on files you don't own provided you have write permission: @@ -7948,8 +7958,8 @@ C<each> function would produce on the same (unmodified) hash. Since Perl security reasons (see L<perlsec/"Algorithmic Complexity Attacks">). As a side effect, calling values() resets the HASH or ARRAY's internal -iterator, see L</each>. (In particular, calling values() in void context -resets the iterator with no other overhead. Apart from resetting the +iterator, see L</each>. (In particular, calling values() in void context +resets the iterator with no other overhead. Apart from resetting the iterator, C<values @array> in list context is the same as plain C<@array>. (We recommend that you use void context C<keys @array> for this, but reasoned that taking C<values @array> out would require more @@ -8228,7 +8238,7 @@ Note that a return value of C<-1> could mean that child processes are being automatically reaped, as described in L<perlipc>. If you use wait in your handler for $SIG{CHLD} it may accidentally for the -child created by qx() or system(). See L<perlipc> for details. +child created by qx() or system(). See L<perlipc> for details. Portability issues: L<perlport/wait>. @@ -8327,7 +8337,8 @@ X<when> =item when BLOCK -C<when> is analogous to the C<case> keyword in other languages. Used with a +C<when> is analogous to the C<case> +keyword in other languages. Used with a C<foreach> loop or the experimental C<given> block, C<when> can be used in Perl to implement C<switch>/C<case> like statements. Available as a statement after Perl 5.10 and as a statement modifier after 5.14. @@ -8386,7 +8397,7 @@ Top of form processing is handled automatically: if there is insufficient room on the current page for the formatted record, the page is advanced by writing a form feed, a special top-of-page format is used to format the new page header before the record is written. By default, the top-of-page -format is the name of the filehandle with "_TOP" appended. This would be a +format is the name of the filehandle with "_TOP" appended. This would be a problem with autovivified filehandles, but it may be dynamically set to the format of your choice by assigning the name to the C<$^> variable while that filehandle is selected. The number of lines remaining on the current |