Change 30709 by [EMAIL PROTECTED] on 2007/03/23 02:06:06
Perforce appararently didn't like integrating this file, since
I had done it twice. It looks like an add will have to do instead.
Affected files ...
... //depot/perl/lib/Pod/Simple/t/perlvaro.txt#1 add
Differences ...
==== //depot/perl/lib/Pod/Simple/t/perlvaro.txt#1 (text) ====
Index: perl/lib/Pod/Simple/t/perlvaro.txt
--- /dev/null 2007-03-19 09:41:43.516454971 -0700
+++ perl/lib/Pod/Simple/t/perlvaro.txt 2007-03-22 19:06:06.000000000 -0700
@@ -0,0 +1,406 @@
+NAME
+perlvar - Perl predefined variables
+DESCRIPTION
+Predefined Names
+The following names have special meaning to Perl. Most punctuation names have
reasonable mnemonics, or analogs in the shells. Nevertheless, if you wish to
use long variable names, you need only say
+ use English;
+at the top of your program. This will alias all the short names to the long
names in the current package. Some even have medium names, generally borrowed
from awk.
+If you don't mind the performance hit, variables that depend on the currently
selected filehandle may instead be set by calling an appropriate object method
on the IO::Handle object. (Summary lines below for this contain the word
HANDLE.) First you must say
+ use IO::Handle;
+after which you may use either
+ method HANDLE EXPR
+or more safely,
+ HANDLE->method(EXPR)
+Each method returns the old value of the IO::Handle attribute. The methods
each take an optional EXPR, which if supplied specifies the new value for the
IO::Handle attribute in question. If not supplied, most methods do nothing to
the current value--except for autoflush(), which will assume a 1 for you, just
to be different. Because loading in the IO::Handle class is an expensive
operation, you should learn how to use the regular built-in variables.
+A few of these variables are considered "read-only". This means that if you
try to assign to this variable, either directly or indirectly through a
reference, you'll raise a run-time exception.
+The following list is ordered by scalar variables first, then the arrays, then
the hashes.
+$ARG
+$_
+The default input and pattern-searching space. The following pairs are
equivalent:
+ while (<>) {...} # equivalent only in while!
+ while (defined($_ = <>)) {...}
+ /^Subject:/
+ $_ =~ /^Subject:/
+ tr/a-z/A-Z/
+ $_ =~ tr/a-z/A-Z/
+ chomp
+ chomp($_)
+Here are the places where Perl will assume $_ even if you don't use it:
+ Various unary functions, including functions like ord() and int(), as well as
the all file tests (-f, -d) except for -t, which defaults to STDIN.
+ Various list functions like print() and unlink().
+ The pattern matching operations m//, s///, and tr/// when used without an =~
operator.
+ The default iterator variable in a foreach loop if no other variable is
supplied.
+ The implicit iterator variable in the grep() and map() functions.
+ The default place to put an input record when a <FH> operation's result is
tested by itself as the sole criterion of a while test. Outside a while test,
this will not happen.
+(Mnemonic: underline is understood in certain operations.)
+$<digits>
+Contains the subpattern from the corresponding set of capturing parentheses
from the last pattern match, not counting patterns matched in nested blocks
that have been exited already. (Mnemonic: like \digits.) These variables are
all read-only and dynamically scoped to the current BLOCK.
+$MATCH
+$&
+The string matched by the last successful pattern match (not counting any
matches hidden within a BLOCK or eval() enclosed by the current BLOCK).
(Mnemonic: like & in some editors.) This variable is read-only and dynamically
scoped to the current BLOCK.
+The use of this variable anywhere in a program imposes a considerable
performance penalty on all regular expression matches. See BUGS.
+$PREMATCH
+$`
+The string preceding whatever was matched by the last successful pattern match
(not counting any matches hidden within a BLOCK or eval enclosed by the current
BLOCK). (Mnemonic: ` often precedes a quoted string.) This variable is
read-only.
+The use of this variable anywhere in a program imposes a considerable
performance penalty on all regular expression matches. See BUGS.
+$POSTMATCH
+$'
+The string following whatever was matched by the last successful pattern match
(not counting any matches hidden within a BLOCK or eval() enclosed by the
current BLOCK). (Mnemonic: ' often follows a quoted string.) Example:
+ $_ = 'abcdefghi';
+ /def/;
+ print "$`:$&:$'\n"; # prints abc:def:ghi
+This variable is read-only and dynamically scoped to the current BLOCK.
+The use of this variable anywhere in a program imposes a considerable
performance penalty on all regular expression matches. See BUGS.
+$LAST_PAREN_MATCH
+$+
+The last bracket matched by the last search pattern. This is useful if you
don't know which one of a set of alternative patterns matched. For example:
+ /Version: (.*)|Revision: (.*)/ && ($rev = $+);
+(Mnemonic: be positive and forward looking.) This variable is read-only and
dynamically scoped to the current BLOCK.
[EMAIL PROTECTED]
[EMAIL PROTECTED]
+This array holds the offsets of the ends of the last successful submatches in
the currently active dynamic scope. $+[0] is the offset into the string of the
end of the entire match. This is the same value as what the pos function
returns when called on the variable that was matched against. The nth element
of this array holds the offset of the nth submatch, so $+[1] is the offset past
where $1 ends, $+[2] the offset past where $2 ends, and so on. You can use $#+
to determine how many subgroups were in the last successful match. See the
examples given for the @- variable.
+$MULTILINE_MATCHING
+$*
+Set to a non-zero integer value to do multi-line matching within a string, 0
(or undefined) to tell Perl that it can assume that strings contain a single
line, for the purpose of optimizing pattern matches. Pattern matches on strings
containing multiple newlines can produce confusing results when $* is 0 or
undefined. Default is undefined. (Mnemonic: * matches multiple things.) This
variable influences the interpretation of only ^ and $. A literal newline can
be searched for even when $* == 0.
+Use of $* is deprecated in modern Perl, supplanted by the /s and /m modifiers
on pattern matching.
+Assigning a non-numerical value to $* triggers a warning (and makes $* act if
$* == 0), while assigning a numerical value to $* makes that an implicit int is
applied on the value.
+input_line_number HANDLE EXPR
+$INPUT_LINE_NUMBER
+$NR
+$.
+The current input record number for the last file handle from which you just
read() (or called a seek or tell on). The value may be different from the
actual physical line number in the file, depending on what notion of "line" is
in effect--see $/ on how to change that. An explicit close on a filehandle
resets the line number. Because <> never does an explicit close, line numbers
increase across ARGV files (but see examples in "eof" in perlfunc). Consider
this variable read-only: setting it does not reposition the seek pointer;
you'll have to do that on your own. Localizing $. has the effect of also
localizing Perl's notion of "the last read filehandle". (Mnemonic: many
programs use "." to mean the current line number.)
+input_record_separator HANDLE EXPR
+$INPUT_RECORD_SEPARATOR
+$RS
+$/
+The input record separator, newline by default. This influences Perl's idea of
what a "line" is. Works like awk's RS variable, including treating empty lines
as a terminator if set to the null string. (An empty line cannot contain any
spaces or tabs.) You may set it to a multi-character string to match a
multi-character terminator, or to undef to read through the end of file.
Setting it to "\n\n" means something slightly different than setting to "", if
the file contains consecutive empty lines. Setting to "" will treat two or more
consecutive empty lines as a single empty line. Setting to "\n\n" will blindly
assume that the next input character belongs to the next paragraph, even if
it's a newline. (Mnemonic: / delimits line boundaries when quoting poetry.)
+ undef $/; # enable "slurp" mode
+ $_ = <FH>; # whole file now here
+ s/\n[ \t]+/ /g;
+Remember: the value of $/ is a string, not a regex. awk has to be better for
something. :-)
+Setting $/ to a reference to an integer, scalar containing an integer, or
scalar that's convertible to an integer will attempt to read records instead of
lines, with the maximum record size being the referenced integer. So this:
+ $/ = \32768; # or \"32768", or \$var_containing_32768
+ open(FILE, $myfile);
+ $_ = <FILE>;
+will read a record of no more than 32768 bytes from FILE. If you're not
reading from a record-oriented file (or your OS doesn't have record-oriented
files), then you'll likely get a full chunk of data with every read. If a
record is larger than the record size you've set, you'll get the record back in
pieces.
+On VMS, record reads are done with the equivalent of sysread, so it's best not
to mix record and non-record reads on the same file. (This is unlikely to be a
problem, because any file you'd want to read in record mode is probably
unusable in line mode.) Non-VMS systems do normal I/O, so it's safe to mix
record and non-record reads of a file.
+See also "Newlines" in perlport. Also see $..
+autoflush HANDLE EXPR
+$OUTPUT_AUTOFLUSH
+$|
+If set to nonzero, forces a flush right away and after every write or print on
the currently selected output channel. Default is 0 (regardless of whether the
channel is really buffered by the system or not; $| tells you only whether
you've asked Perl explicitly to flush after each write). STDOUT will typically
be line buffered if output is to the terminal and block buffered otherwise.
Setting this variable is useful primarily when you are outputting to a pipe or
socket, such as when you are running a Perl program under rsh and want to see
the output as it's happening. This has no effect on input buffering. See "getc"
in perlfunc for that. (Mnemonic: when you want your pipes to be piping hot.)
+output_field_separator HANDLE EXPR
+$OUTPUT_FIELD_SEPARATOR
+$OFS
+$,
+The output field separator for the print operator. Ordinarily the print
operator simply prints out its arguments without further adornment. To get
behavior more like awk, set this variable as you would set awk's OFS variable
to specify what is printed between fields. (Mnemonic: what is printed when
there is a "," in your print statement.)
+output_record_separator HANDLE EXPR
+$OUTPUT_RECORD_SEPARATOR
+$ORS
+$\
+The output record separator for the print operator. Ordinarily the print
operator simply prints out its arguments as is, with no trailing newline or
other end-of-record string added. To get behavior more like awk, set this
variable as you would set awk's ORS variable to specify what is printed at the
end of the print. (Mnemonic: you set $\ instead of adding "\n" at the end of
the print. Also, it's just like $/, but it's what you get "back" from Perl.)
+$LIST_SEPARATOR
+$"
+This is like $, except that it applies to array and slice values interpolated
into a double-quoted string (or similar interpreted string). Default is a
space. (Mnemonic: obvious, I think.)
+$SUBSCRIPT_SEPARATOR
+$SUBSEP
+$;
+The subscript separator for multidimensional array emulation. If you refer to
a hash element as
+ $foo{$a,$b,$c}
+it really means
+ $foo{join($;, $a, $b, $c)}
+But don't put
+ @foo{$a,$b,$c} # a slice--note the @
+which means
+ ($foo{$a},$foo{$b},$foo{$c})
+Default is "\034", the same as SUBSEP in awk. If your keys contain binary data
there might not be any safe value for $;. (Mnemonic: comma (the syntactic
subscript separator) is a semi-semicolon. Yeah, I know, it's pretty lame, but
$, is already taken for something more important.)
+Consider using "real" multidimensional arrays as described in perllol.
+$OFMT
+$#
+The output format for printed numbers. This variable is a half-hearted attempt
to emulate awk's OFMT variable. There are times, however, when awk and Perl
have differing notions of what counts as numeric. The initial value is "%.ng",
where n is the value of the macro DBL_DIG from your system's float.h. This is
different from awk's default OFMT setting of "%.6g", so you need to set $#
explicitly to get awk's value. (Mnemonic: # is the number sign.)
+Use of $# is deprecated.
+format_page_number HANDLE EXPR
+$FORMAT_PAGE_NUMBER
+$%
+The current page number of the currently selected output channel. Used with
formats. (Mnemonic: % is page number in nroff.)
+format_lines_per_page HANDLE EXPR
+$FORMAT_LINES_PER_PAGE
+$=
+The current page length (printable lines) of the currently selected output
channel. Default is 60. Used with formats. (Mnemonic: = has horizontal lines.)
+format_lines_left HANDLE EXPR
+$FORMAT_LINES_LEFT
+$-
+The number of lines left on the page of the currently selected output channel.
Used with formats. (Mnemonic: lines_on_page - lines_printed.)
[EMAIL PROTECTED]
[EMAIL PROTECTED]
+$-[0] is the offset of the start of the last successful match. $-[n] is the
offset of the start of the substring matched by n-th subpattern, or undef if
the subpattern did not match.
+Thus after a match against $_, $& coincides with substr $_, $-[0], $+[0] -
$-[0]. Similarly, $n coincides with substr $_, $-[n], $+[n] - $-[n] if $-[n] is
defined, and $+ coincides with substr $_, $-[$#-], $+[$#-]. One can use $#- to
find the last matched subgroup in the last successful match. Contrast with $#+,
the number of subgroups in the regular expression. Compare with @+.
+This array holds the offsets of the beginnings of the last successful
submatches in the currently active dynamic scope. $-[0] is the offset into the
string of the beginning of the entire match. The nth element of this array
holds the offset of the nth submatch, so $+[1] is the offset where $1 begins,
$+[2] the offset where $2 begins, and so on. You can use $#- to determine how
many subgroups were in the last successful match. Compare with the @+ variable.
+After a match against some variable $var:
+$` is the same as substr($var, 0, $-[0])
+$& is the same as substr($var, $-[0], $+[0] - $-[0])
+$' is the same as substr($var, $+[0])
+$1 is the same as substr($var, $-[1], $+[1] - $-[1])
+$2 is the same as substr($var, $-[2], $+[2] - $-[2])
+$3 is the same as substr $var, $-[3], $+[3] - $-[3])
+format_name HANDLE EXPR
+$FORMAT_NAME
+$~
+The name of the current report format for the currently selected output
channel. Default is the name of the filehandle. (Mnemonic: brother to $^.)
+format_top_name HANDLE EXPR
+$FORMAT_TOP_NAME
+$^
+The name of the current top-of-page format for the currently selected output
channel. Default is the name of the filehandle with _TOP appended. (Mnemonic:
points to top of page.)
+format_line_break_characters HANDLE EXPR
+$FORMAT_LINE_BREAK_CHARACTERS
+$:
+The current set of characters after which a string may be broken to fill
continuation fields (starting with ^) in a format. Default is " \n-", to break
on whitespace or hyphens. (Mnemonic: a "colon" in poetry is a part of a line.)
+format_formfeed HANDLE EXPR
+$FORMAT_FORMFEED
+$^L
+What formats output as a form feed. Default is \f.
+$ACCUMULATOR
+$^A
+The current value of the write() accumulator for format() lines. A format
contains formline() calls that put their result into $^A. After calling its
format, write() prints out the contents of $^A and empties. So you never really
see the contents of $^A unless you call formline() yourself and then look at
it. See perlform and "formline()" in perlfunc.
+$CHILD_ERROR
+$?
+The status returned by the last pipe close, backtick (``) command, successful
call to wait() or waitpid(), or from the system() operator. This is just the
16-bit status word returned by the wait() system call (or else is made up to
look like it). Thus, the exit value of the subprocess is really ($? >> 8), and
$? & 127 gives which signal, if any, the process died from, and $? & 128
reports whether there was a core dump. (Mnemonic: similar to sh and ksh.)
+Additionally, if the h_errno variable is supported in C, its value is returned
via $? if any gethost*() function fails.
+If you have installed a signal handler for SIGCHLD, the value of $? will
usually be wrong outside that handler.
+Inside an END subroutine $? contains the value that is going to be given to
exit(). You can modify $? in an END subroutine to change the exit status of
your program. For example:
+ END {
+ $? = 1 if $? == 255; # die would make it 255
+ }
+Under VMS, the pragma use vmsish 'status' makes $? reflect the actual VMS exit
status, instead of the default emulation of POSIX status.
+Also see "Error Indicators".
+$OS_ERROR
+$ERRNO
+$!
+If used numerically, yields the current value of the C errno variable, with
all the usual caveats. (This means that you shouldn't depend on the value of $!
to be anything in particular unless you've gotten a specific error return
indicating a system error.) If used an a string, yields the corresponding
system error string. You can assign a number to $! to set errno if, for
instance, you want "$!" to return the string for error n, or you want to set
the exit value for the die() operator. (Mnemonic: What just went bang?)
+Also see "Error Indicators".
+$EXTENDED_OS_ERROR
+$^E
+Error information specific to the current operating system. At the moment,
this differs from $! under only VMS, OS/2, and Win32 (and for MacPerl). On all
other platforms, $^E is always just the same as $!.
+Under VMS, $^E provides the VMS status value from the last system error. This
is more specific information about the last system error than that provided by
$!. This is particularly important when $! is set to EVMSERR.
+Under OS/2, $^E is set to the error code of the last call to OS/2 API either
via CRT, or directly from perl.
+Under Win32, $^E always returns the last error information reported by the
Win32 call GetLastError() which describes the last error from within the Win32
API. Most Win32-specific code will report errors via $^E. ANSI C and Unix-like
calls set errno and so most portable Perl code will report errors via $!.
+Caveats mentioned in the description of $! generally apply to $^E, also.
(Mnemonic: Extra error explanation.)
+Also see "Error Indicators".
+$EVAL_ERROR
+$@
+The Perl syntax error message from the last eval() operator. If null, the last
eval() parsed and executed correctly (although the operations you invoked may
have failed in the normal fashion). (Mnemonic: Where was the syntax error "at"?)
+Warning messages are not collected in this variable. You can, however, set up
a routine to process warnings by setting $SIG{__WARN__} as described below.
+Also see "Error Indicators".
+$PROCESS_ID
+$PID
+$$
+The process number of the Perl running this script. You should consider this
variable read-only, although it will be altered across fork() calls. (Mnemonic:
same as shells.)
+$REAL_USER_ID
+$UID
+$<
+The real uid of this process. (Mnemonic: it's the uid you came from, if you're
running setuid.)
+$EFFECTIVE_USER_ID
+$EUID
+$>
+The effective uid of this process. Example:
+ $< = $>; # set real to effective uid
+ ($<,$>) = ($>,$<); # swap real and effective uid
+(Mnemonic: it's the uid you went to, if you're running setuid.) $< and $> can
be swapped only on machines supporting setreuid().
+$REAL_GROUP_ID
+$GID
+$(
+The real gid of this process. If you are on a machine that supports membership
in multiple groups simultaneously, gives a space separated list of groups you
are in. The first number is the one returned by getgid(), and the subsequent
ones by getgroups(), one of which may be the same as the first number.
+However, a value assigned to $( must be a single number used to set the real
gid. So the value given by $( should not be assigned back to $( without being
forced numeric, such as by adding zero.
+(Mnemonic: parentheses are used to group things. The real gid is the group you
left, if you're running setgid.)
+$EFFECTIVE_GROUP_ID
+$EGID
+$)
+The effective gid of this process. If you are on a machine that supports
membership in multiple groups simultaneously, gives a space separated list of
groups you are in. The first number is the one returned by getegid(), and the
subsequent ones by getgroups(), one of which may be the same as the first
number.
+Similarly, a value assigned to $) must also be a space-separated list of
numbers. The first number sets the effective gid, and the rest (if any) are
passed to setgroups(). To get the effect of an empty list for setgroups(), just
repeat the new effective gid; that is, to force an effective gid of 5 and an
effectively empty setgroups() list, say $) = "5 5" .
+(Mnemonic: parentheses are used to group things. The effective gid is the
group that's right for you, if you're running setgid.)
+$<, $>, $( and $) can be set only on machines that support the corresponding
set[re][ug]id() routine. $( and $) can be swapped only on machines supporting
setregid().
+$PROGRAM_NAME
+$0
+Contains the name of the program being executed. On some operating systems
assigning to $0 modifies the argument area that the ps program sees. This is
more useful as a way of indicating the current program state than it is for
hiding the program you're running. (Mnemonic: same as sh and ksh.)
+Note for BSD users: setting $0 does not completely remove "perl" from the
ps(1) output. For example, setting $0 to "foobar" will result in "perl: foobar
(perl)". This is an operating system feature.
+$[
+The index of the first element in an array, and of the first character in a
substring. Default is 0, but you could theoretically set it to 1 to make Perl
behave more like awk (or Fortran) when subscripting and when evaluating the
index() and substr() functions. (Mnemonic: [ begins subscripts.)
+As of release 5 of Perl, assignment to $[ is treated as a compiler directive,
and cannot influence the behavior of any other file. Its use is highly
discouraged.
+$]
+The version + patchlevel / 1000 of the Perl interpreter. This variable can be
used to determine whether the Perl interpreter executing a script is in the
right range of versions. (Mnemonic: Is this version of perl in the right
bracket?) Example:
+ warn "No checksumming!\n" if $] < 3.019;
+See also the documentation of use VERSION and require VERSION for a convenient
way to fail if the running Perl interpreter is too old.
+The use of this variable is deprecated. The floating point representation can
sometimes lead to inaccurate numeric comparisons. See $^V for a more modern
representation of the Perl version that allows accurate string comparisons.
+$COMPILING
+$^C
+The current value of the flag associated with the -c switch. Mainly of use
with -MO=... to allow code to alter its behavior when being compiled, such as
for example to AUTOLOAD at compile time rather than normal, deferred loading.
See perlcc. Setting $^C = 1 is similar to calling B::minus_c.
+$DEBUGGING
+$^D
+The current value of the debugging flags. (Mnemonic: value of -D switch.)
+$SYSTEM_FD_MAX
+$^F
+The maximum system file descriptor, ordinarily 2. System file descriptors are
passed to exec()ed processes, while higher file descriptors are not. Also,
during an open(), system file descriptors are preserved even if the open()
fails. (Ordinary file descriptors are closed before the open() is attempted.)
The close-on-exec status of a file descriptor will be decided according to the
value of $^F when the corresponding file, pipe, or socket was opened, not the
time of the exec().
+$^H
+WARNING: This variable is strictly for internal use only. Its availability,
behavior, and contents are subject to change without notice.
+This variable contains compile-time hints for the Perl interpreter. At the end
of compilation of a BLOCK the value of this variable is restored to the value
when the interpreter started to compile the BLOCK.
+When perl begins to parse any block construct that provides a lexical scope
(e.g., eval body, required file, subroutine body, loop body, or conditional
block), the existing value of $^H is saved, but its value is left unchanged.
When the compilation of the block is completed, it regains the saved value.
Between the points where its value is saved and restored, code that executes
within BEGIN blocks is free to change the value of $^H.
+This behavior provides the semantic of lexical scoping, and is used in, for
instance, the use strict pragma.
+The contents should be an integer; different bits of it are used for different
pragmatic flags. Here's an example:
+ sub add_100 { $^H |= 0x100 }
+ sub foo {
+ BEGIN { add_100() }
+ bar->baz($boon);
+ }
+Consider what happens during execution of the BEGIN block. At this point the
BEGIN block has already been compiled, but the body of foo() is still being
compiled. The new value of $^H will therefore be visible only while the body of
foo() is being compiled.
+Substitution of the above BEGIN block with:
+ BEGIN { require strict; strict->import('vars') }
+demonstrates how use strict 'vars' is implemented. Here's a conditional
version of the same lexical pragma:
+ BEGIN { require strict; strict->import('vars') if $condition }
+%^H
+WARNING: This variable is strictly for internal use only. Its availability,
behavior, and contents are subject to change without notice.
+The %^H hash provides the same scoping semantic as $^H. This makes it useful
for implementation of lexically scoped pragmas.
+$INPLACE_EDIT
+$^I
+The current value of the inplace-edit extension. Use undef to disable inplace
editing. (Mnemonic: value of -i switch.)
+$^M
+By default, running out of memory is an untrappable, fatal error. However, if
suitably built, Perl can use the contents of $^M as an emergency memory pool
after die()ing. Suppose that your Perl were compiled with -DPERL_EMERGENCY_SBRK
and used Perl's malloc. Then
+ $^M = 'a' x (1 << 16);
+would allocate a 64K buffer for use in an emergency. See the INSTALL file in
the Perl distribution for information on how to enable this option. To
discourage casual use of this advanced feature, there is no English long name
for this variable.
+$OSNAME
+$^O
+The name of the operating system under which this copy of Perl was built, as
determined during the configuration process. The value is identical to
$Config{'osname'}. See also Config and the -V command-line switch documented in
perlrun.
+$PERLDB
+$^P
+The internal variable for debugging support. The meanings of the various bits
are subject to change, but currently indicate:
+0x01
+Debug subroutine enter/exit.
+0x02
+Line-by-line debugging.
+0x04
+Switch off optimizations.
+0x08
+Preserve more data for future interactive inspections.
+0x10
+Keep info about source lines on which a subroutine is defined.
+0x20
+Start with single-step on.
+0x40
+Use subroutine address instead of name when reporting.
+0x80
+Report goto &subroutine as well.
+0x100
+Provide informative "file" names for evals based on the place they were
compiled.
+0x200
+Provide informative names to anonymous subroutines based on the place they
were compiled.
+Some bits may be relevant at compile-time only, some at run-time only. This is
a new mechanism and the details may change.
+$LAST_REGEXP_CODE_RESULT
+$^R
+The result of evaluation of the last successful (?{ code }) regular expression
assertion (see perlre). May be written to.
+$EXCEPTIONS_BEING_CAUGHT
+$^S
+Current state of the interpreter. Undefined if parsing of the current
module/eval is not finished (may happen in $SIG{__DIE__} and $SIG{__WARN__}
handlers). True if inside an eval(), otherwise false.
+$BASETIME
+$^T
+The time at which the program began running, in seconds since the epoch
(beginning of 1970). The values returned by the -M, -A, and -C filetests are
based on this value.
+$PERL_VERSION
+$^V
+The revision, version, and subversion of the Perl interpreter, represented as
a string composed of characters with those ordinals. Thus in Perl v5.6.0 it
equals chr(5) . chr(6) . chr(0) and will return true for $^V eq v5.6.0. Note
that the characters in this string value can potentially be in Unicode range.
+This can be used to determine whether the Perl interpreter executing a script
is in the right range of versions. (Mnemonic: use ^V for Version Control.)
Example:
+ warn "No \"our\" declarations!\n" if $^V and $^V lt v5.6.0;
+See the documentation of use VERSION and require VERSION for a convenient way
to fail if the running Perl interpreter is too old.
+See also $] for an older representation of the Perl version.
+$WARNING
+$^W
+The current value of the warning switch, initially true if -w was used, false
otherwise, but directly modifiable. (Mnemonic: related to the -w switch.) See
also warnings.
+${^WARNING_BITS}
+The current set of warning checks enabled by the use warnings pragma. See the
documentation of warnings for more details.
+${^WIDE_SYSTEM_CALLS}
+Global flag that enables system calls made by Perl to use wide character APIs
native to the system, if available. This is currently only implemented on the
Windows platform.
+This can also be enabled from the command line using the -C switch.
+The initial value is typically 0 for compatibility with Perl versions earlier
than 5.6, but may be automatically set to 1 by Perl if the system provides a
user-settable default (e.g., $ENV{LC_CTYPE}).
+The bytes pragma always overrides the effect of this flag in the current
lexical scope. See bytes.
+$EXECUTABLE_NAME
+$^X
+The name that the Perl binary itself was executed as, from C's argv[0]. This
may not be a full pathname, nor even necessarily in your path.
+$ARGV
+contains the name of the current file when reading from <>.
[EMAIL PROTECTED]
+The array @ARGV contains the command-line arguments intended for the script.
$#ARGV is generally the number of arguments minus one, because $ARGV[0] is the
first argument, not the program's command name itself. See $0 for the command
name.
[EMAIL PROTECTED]
+The array @INC contains the list of places that the do EXPR, require, or use
constructs look for their library files. It initially consists of the arguments
to any -I command-line switches, followed by the default Perl library, probably
/usr/local/lib/perl, followed by ".", to represent the current directory. If
you need to modify this at runtime, you should use the use lib pragma to get
the machine-dependent library properly loaded also:
+ use lib '/mypath/libdir/';
+ use SomeMod;
[EMAIL PROTECTED]
+Within a subroutine the array @_ contains the parameters passed to that
subroutine. See perlsub.
+%INC
+The hash %INC contains entries for each filename included via the do, require,
or use operators. The key is the filename you specified (with module names
converted to pathnames), and the value is the location of the file found. The
require operator uses this hash to determine whether a particular file has
already been included.
+%ENV
+$ENV{expr}
+The hash %ENV contains your current environment. Setting a value in ENV
changes the environment for any child processes you subsequently fork() off.
+%SIG
+$SIG{expr}
+The hash %SIG contains signal handlers for signals. For example:
+ sub handler { # 1st argument is signal name
+ my($sig) = @_;
+ print "Caught a SIG$sig--shutting down\n";
+ close(LOG);
+ exit(0);
+ }
+ $SIG{'INT'} = \&handler;
+ $SIG{'QUIT'} = \&handler;
+ ...
+ $SIG{'INT'} = 'DEFAULT'; # restore default action
+ $SIG{'QUIT'} = 'IGNORE'; # ignore SIGQUIT
+Using a value of 'IGNORE' usually has the effect of ignoring the signal,
except for the CHLD signal. See perlipc for more about this special case.
+Here are some other examples:
+ $SIG{"PIPE"} = "Plumber"; # assumes main::Plumber (not recommended)
+ $SIG{"PIPE"} = \&Plumber; # just fine; assume current Plumber
+ $SIG{"PIPE"} = *Plumber; # somewhat esoteric
+ $SIG{"PIPE"} = Plumber(); # oops, what did Plumber() return??
+Be sure not to use a bareword as the name of a signal handler, lest you
inadvertently call it.
+If your system has the sigaction() function then signal handlers are installed
using it. This means you get reliable signal handling. If your system has the
SA_RESTART flag it is used when signals handlers are installed. This means that
system calls for which restarting is supported continue rather than returning
when a signal arrives. If you want your system calls to be interrupted by
signal delivery then do something like this:
+ use POSIX ':signal_h';
+ my $alarm = 0;
+ sigaction SIGALRM, new POSIX::SigAction sub { $alarm = 1 }
+ or die "Error setting SIGALRM handler: $!\n";
+See POSIX.
+Certain internal hooks can be also set using the %SIG hash. The routine
indicated by $SIG{__WARN__} is called when a warning message is about to be
printed. The warning message is passed as the first argument. The presence of a
__WARN__ hook causes the ordinary printing of warnings to STDERR to be
suppressed. You can use this to save warnings in a variable, or turn warnings
into fatal errors, like this:
+ local $SIG{__WARN__} = sub { die $_[0] };
+ eval $proggie;
+The routine indicated by $SIG{__DIE__} is called when a fatal exception is
about to be thrown. The error message is passed as the first argument. When a
__DIE__ hook routine returns, the exception processing continues as it would
have in the absence of the hook, unless the hook routine itself exits via a
goto, a loop exit, or a die(). The __DIE__ handler is explicitly disabled
during the call, so that you can die from a __DIE__ handler. Similarly for
__WARN__.
+Due to an implementation glitch, the $SIG{__DIE__} hook is called even inside
an eval(). Do not use this to rewrite a pending exception in $@, or as a
bizarre substitute for overriding CORE::GLOBAL::die(). This strange action at a
distance may be fixed in a future release so that $SIG{__DIE__} is only called
if your program is about to exit, as was the original intent. Any other use is
deprecated.
+__DIE__/__WARN__ handlers are very special in one respect: they may be called
to report (probable) errors found by the parser. In such a case the parser may
be in inconsistent state, so any attempt to evaluate Perl code from such a
handler will probably result in a segfault. This means that warnings or errors
that result from parsing Perl should be used with extreme caution, like this:
+ require Carp if defined $^S;
+ Carp::confess("Something wrong") if defined &Carp::confess;
+ die "Something wrong, but could not load Carp to give backtrace...
+ To see backtrace try starting Perl with -MCarp switch";
+Here the first line will load Carp unless it is the parser who called the
handler. The second line will print backtrace and die if Carp was available.
The third line will be executed only if Carp was not available.
+See "die" in perlfunc, "warn" in perlfunc, "eval" in perlfunc, and warnings
for additional information.
+Error Indicators
+The variables $@, $!, $^E, and $? contain information about different types of
error conditions that may appear during execution of a Perl program. The
variables are shown ordered by the "distance" between the subsystem which
reported the error and the Perl process. They correspond to errors detected by
the Perl interpreter, C library, operating system, or an external program,
respectively.
+To illustrate the differences between these variables, consider the following
Perl expression, which uses a single-quoted string:
+ eval q{
+ open PIPE, "/cdrom/install |";
+ @res = <PIPE>;
+ close PIPE or die "bad pipe: $?, $!";
+ };
+After execution of this statement all 4 variables may have been set.
+$@ is set if the string to be eval-ed did not compile (this may happen if open
or close were imported with bad prototypes), or if Perl code executed during
evaluation die()d . In these cases the value of $@ is the compile error, or the
argument to die (which will interpolate $! and $?!). (See also Fatal, though.)
+When the eval() expression above is executed, open(), <PIPE>, and close are
translated to calls in the C run-time library and thence to the operating
system kernel. $! is set to the C library's errno if one of these calls fails.
+Under a few operating systems, $^E may contain a more verbose error indicator,
such as in this case, "CDROM tray not closed." Systems that do not support
extended error messages leave $^E the same as $!.
+Finally, $? may be set to non-0 value if the external program /cdrom/install
fails. The upper eight bits reflect specific error conditions encountered by
the program (the program's exit() value). The lower eight bits reflect mode of
failure, like signal death and core dump information See wait(2) for details.
In contrast to $! and $^E, which are set only if error condition is detected,
the variable $? is set on each wait or pipe close, overwriting the old value.
This is more like $@, which on every eval() is always set on failure and
cleared on success.
+For more details, see the individual descriptions at $@, $!, $^E, and $?.
+Technical Note on the Syntax of Variable Names
+Variable names in Perl can have several formats. Usually, they must begin with
a letter or underscore, in which case they can be arbitrarily long (up to an
internal limit of 251 characters) and may contain letters, digits, underscores,
or the special sequence :: or '. In this case, the part before the last :: or '
is taken to be a package qualifier; see perlmod.
+Perl variable names may also be a sequence of digits or a single punctuation
or control character. These names are all reserved for special uses by Perl;
for example, the all-digits names are used to hold data captured by
backreferences after a regular expression match. Perl has a special syntax for
the single-control-character names: It understands ^X (caret X) to mean the
control-X character. For example, the notation $^W (dollar-sign caret W) is the
scalar variable whose name is the single character control-W. This is better
than typing a literal control-W into your program.
+Finally, new in Perl 5.6, Perl variable names may be alphanumeric strings that
begin with control characters (or better yet, a caret). These variables must be
written in the form ${^Foo}; the braces are not optional. ${^Foo} denotes the
scalar variable whose name is a control-F followed by two o's. These variables
are reserved for future special uses by Perl, except for the ones that begin
with ^_ (control-underscore or caret-underscore). No control-character name
that begins with ^_ will acquire a special meaning in any future version of
Perl; such names may therefore be used safely in programs. $^_ itself, however,
is reserved.
+Perl identifiers that begin with digits, control characters, or punctuation
characters are exempt from the effects of the package declaration and are
always forced to be in package main. A few other names are also exempt:
+ ENV STDIN
+ INC STDOUT
+ ARGV STDERR
+ ARGVOUT
+ SIG
+In particular, the new special ${^_XYZ} variables are always taken to be in
package main, regardless of any package declarations presently in scope.
+BUGS
+Due to an unfortunate accident of Perl's implementation, use English imposes a
considerable performance penalty on all regular expression matches in a
program, regardless of whether they occur in the scope of use English. For that
reason, saying use English in libraries is strongly discouraged. See the
Devel::SawAmpersand module documentation from CPAN
(http://www.perl.com/CPAN/modules/by-module/Devel/) for more information.
+Having to even think about the $^S variable in your exception handlers is
simply wrong. $SIG{__DIE__} as currently implemented invites grievous and
difficult to track down errors. Avoid it and use an END{} or CORE::GLOBAL::die
override instead.
End of Patch.
