=item Functions for filehandles, files, or directories
--X, chdir, chmod, chown, chroot, fcntl, glob, ioctl, link,
+I<-X>, chdir, chmod, chown, chroot, fcntl, glob, ioctl, link,
lstat, mkdir, open, opendir, readlink, rename, rmdir,
stat, symlink, umask, unlink, utime
=item Functions new in perl5
abs, bless, chomp, chr, exists, formline, glob, import, lc,
-lcfirst, map, my, no, qx, qw, ref, sub*, sysopen, tie, tied, uc,
-ucfirst, untie, use
+lcfirst, map, my, no, prototype, qx, qw, readline, readpipe,
+ref, sub*, sysopen, tie, tied, uc, ucfirst, untie, use
* - C<sub> was a keyword in perl4, but in perl5 it is an
operator which can be used in expressions.
=item each ASSOC_ARRAY
-Returns a 2-element array consisting of the key and value for the next
-value of an associative array, so that you can iterate over it.
+When called in a list context, returns a 2-element array consisting
+of the key and value for the next element of an associative array,
+so that you can iterate over it. When called in a scalar context,
+returns the key only for the next element in the associative array.
Entries are returned in an apparently random order. When the array is
-entirely read, a null array is returned (which when assigned produces a
-FALSE (0) value). The next call to each() after that will start
+entirely read, a null array is returned in list context (which when
+assigned produces a FALSE (0) value), and C<undef> is returned in a
+scalar context. The next call to each() after that will start
iterating again. The iterator can be reset only by reading all the
elements from the array. You should not add elements to an array while
you're iterating over it. There is a single iterator for each
$login = getlogin || (getpwuid($<))[0] || "Kilroy";
-Do not consider getlogin() for authorentication: it is not as
+Do not consider getlogin() for authentication: it is not as
secure as getpwuid().
=item getpeername SOCKET
process groups instead of processes. (On System V, a negative I<PROCESS>
number will also kill process groups, but that's not portable.) That
means you usually want to use positive not negative signals. You may also
-use a signal name in quotes. See the L<perlipc/"Signals"> man page for details.
+use a signal name in quotes. See L<perlipc/"Signals"> for details.
=item last LABEL
$now_string = localtime; # e.g. "Thu Oct 13 04:54:34 1994"
Also see the F<timelocal.pl> library, and the strftime(3) function available
-via the POSIX modulie.
+via the POSIX module.
=item log EXPR
as a command to which output is to be piped, and if the filename ends with
a "|", the filename is interpreted See L<perlipc/"Using open() for IPC">
for more examples of this. as command which pipes input to us. (You may
-not have a raw open() to a command that pipes both in I<and> out, but see See L<open2>,
+not have a raw open() to a command that pipes both in I<and> out, but see L<open2>,
L<open3>, and L<perlipc/"Bidirectional Communication"> for alternatives.)
Opening '-' opens STDIN and opening '>-' opens STDOUT. Open returns
token is a term, it may be misinterpreted as an operator unless you
interpose a + or put parens around the arguments.) If FILEHANDLE is
omitted, prints by default to standard output (or to the last selected
-output channel--see select()). If LIST is also omitted, prints $_ to
+output channel--see L</select>). If LIST is also omitted, prints $_ to
STDOUT. To set the default output channel to something other than
STDOUT use the select operation. Note that, because print takes a
LIST, anything in the LIST is evaluated in a list context, and any
put parens around all the arguments.
Note that if you're storing FILEHANDLES in an array or other expression,
-you will have to use a block returning its value instead
+you will have to use a block returning its value instead:
print { $files[$i] } "stuff\n";
print { $OK ? STDOUT : STDERR } "stuff\n";
Equivalent to a "print FILEHANDLE sprintf(LIST)". The first argument
of the list will be interpreted as the printf format.
+=item prototype FUNCTION
+
+Returns the prototype of a function as a string (or C<undef> if the
+function has no prototype). FUNCTION is a reference to the the
+function whose prototype you want to retrieve.
+
=item push ARRAY,LIST
Treats ARRAY as a stack, and pushes the values of LIST
otherwise. But it's better just to put the "C<1;>", in case you add more
statements.
-If EXPR is a bare word, the require assumes a "F<.pm>" extension for you,
+If EXPR is a bare word, the require assumes a "F<.pm>" extension and
+replaces "F<::>" with "F</>" in the filename for you,
to make it easy to load standard modules. This form of loading of
modules does not risk altering your namespace.
-For a yet-more-powerful import facility, see the L</use()> and
+For a yet-more-powerful import facility, see L</use> and
L<perlmod>.
=item reset EXPR
Resetting "A-Z" is not recommended since you'll wipe out your
ARGV and ENV arrays. Only resets package variables--lexical variables
are unaffected, but they clean themselves up on scope exit anyway,
-so anymore you probably want to use them instead. See L</my>.
+so you'll probably want to use them instead. See L</my>.
=item return LIST
capable of returning the $timeleft. If not, they always return
$timeleft equal to the supplied $timeout.
-You can effect a 250-microsecond sleep this way:
+You can effect a 250-millisecond sleep this way:
select(undef, undef, undef, 0.25);
If the PATTERN contains parentheses, additional array elements are
created from each matching substring in the delimiter.
- split(/([,-])/, "1-10,20");
+ split(/([,-])/, "1-10,20", 3);
produces the list value
=item srand EXPR
Sets the random number seed for the C<rand> operator. If EXPR is omitted,
-does C<srand(time)>. Many folks use an explicit C<srand(time ^ $$)>
-instead. Of course, you'd need something much more random than that for
+uses a semirandom value based on the current time and process ID, among
+other things. Of course, you'd need something much more random than that for
cryptographic purposes, since it's easy to guess the current time.
Checksumming the compressed output of rapidly changing operating system
status programs is the usual method. Examples are posted regularly to
# print out history file offsets
use NDBM_File;
- tie(%HIST, NDBM_File, '/usr/lib/news/history', 1, 0);
+ tie(%HIST, 'NDBM_File', '/usr/lib/news/history', 1, 0);
while (($key,$val) = each %HIST) {
print $key, ' = ', unpack('L',$val), "\n";
}
=item time
-Returns the number of non-leap seconds since 00:00:00 UTC, January 1,
-1970. Suitable for feeding to gmtime() and localtime().
+Returns the number of non-leap seconds since whatever time the system
+considers to be the epoch (that's 00:00:00, January 1, 1904 for MacOS,
+and 00:00:00 UTC, January 1, 1970 for most other systems).
+Suitable for feeding to gmtime() and localtime().
=item times
=item use Module
+=item use Module VERSION LIST
+
+=item use VERSION
+
Imports some semantics into the current package from the named module,
generally by aliasing certain subroutine or variable names into your
package. It is exactly equivalent to
BEGIN { require Module; import Module LIST; }
+except that Module I<must> be a bare word.
+
+If the first argument to C<use> is a number, it is treated as a version
+number instead of a module name. If the version of the Perl interpreter
+is less than VERSION, then an error message is printed and Perl exits
+immediately. This is often useful if you need to check the current
+Perl version before C<use>ing library modules which have changed in
+incompatible ways from older versions of Perl. (We try not to do
+this more than we have to.)
+
The BEGIN forces the require and import to happen at compile time. The
require makes sure the module is loaded into memory if it hasn't been
yet. The import is not a builtin--it's just an ordinary static method
BEGIN { require Module; }
+If the VERSION argument is present between Module and LIST, then the
+C<use> will fail if the C<$VERSION> variable in package Module is
+less than VERSION.
+
Because this is a wide-open interface, pragmas (compiler directives)
are also implemented this way. Currently implemented pragmas are:
effective through the end of the file).
There's a corresponding "no" command that unimports meanings imported
-by use.
+by use, i.e. it calls C<unimport Module LIST> instead of C<import>.
no integer;
no strict 'refs';
projects / p5sagit/p5-mst-13.2.git / blobdiff