perl58delta.1

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

in most \s-1UNIX\s0 platforms).  (\fIbsd_glob()\fR does still sort platform
natively, \s-1ASCII\s0 or \s-1EBCDIC\s0, unless \s-1GLOB_ALPHASORT\s0 is specified.) [561]
.Sh "Deprecations"
.IX Subsection "Deprecations"
.IP "\(bu" 4
The semantics of bless(\s-1REF\s0, \s-1REF\s0) were unclear and until someone proves
it to make some sense, it is forbidden.
.IP "\(bu" 4
The obsolete chat2 library that should never have been allowed
to escape the laboratory has been decommissioned.
.IP "\(bu" 4
Using chdir("") or chdir(undef) instead of explicit \fIchdir()\fR is
doubtful.  A failure (think chdir(\fIsome_function()\fR) can lead into
unintended \fIchdir()\fR to the home directory, therefore this behaviour
is deprecated.
.IP "\(bu" 4
The builtin \fIdump()\fR function has probably outlived most of its
usefulness.  The core-dumping functionality will remain in future
available as an explicit call to \f(CW\*(C`CORE::dump()\*(C'\fR, but in future
releases the behaviour of an unqualified \f(CW\*(C`dump()\*(C'\fR call may change.
.IP "\(bu" 4
The very dusty examples in the eg/ directory have been removed.
Suggestions for new shiny examples welcome but the main issue is that
the examples need to be documented, tested and (most importantly)
maintained.
.IP "\(bu" 4
The (bogus) escape sequences \e8 and \e9 now give an optional warning
(\*(L"Unrecognized escape passed through\*(R").  There is no need to \e\-escape
any \f(CW\*(C`\ew\*(C'\fR character.
.IP "\(bu" 4
The *glob{\s-1FILEHANDLE\s0} is deprecated, use *glob{\s-1IO\s0} instead.
.IP "\(bu" 4
The \f(CW\*(C`package;\*(C'\fR syntax (\f(CW\*(C`package\*(C'\fR without an argument) has been
deprecated.  Its semantics were never that clear and its
implementation even less so.  If you have used that feature to
disallow all but fully qualified variables, \f(CW\*(C`use strict;\*(C'\fR instead.
.IP "\(bu" 4
The unimplemented \s-1POSIX\s0 regex features [[.cc.]] and [[=c=]] are still
recognised but now cause fatal errors.  The previous behaviour of
ignoring them by default and warning if requested was unacceptable
since it, in a way, falsely promised that the features could be used.
.IP "\(bu" 4
In future releases, non-PerlIO aware \s-1XS\s0 modules may become completely
unsupported.  Since PerlIO is a drop-in replacement for stdio at the
source code level, this shouldn't be that drastic a change.
.IP "\(bu" 4
Previous versions of perl and some readings of some sections of Camel
\&\s-1III\s0 implied that the \f(CW\*(C`:raw\*(C'\fR \*(L"discipline\*(R" was the inverse of \f(CW\*(C`:crlf\*(C'\fR.
Turning off \*(L"clrfness\*(R" is no longer enough to make a stream truly
binary. So the PerlIO \f(CW\*(C`:raw\*(C'\fR layer (or \*(L"discipline\*(R", to use the Camel
book's older terminology) is now formally defined as being equivalent
to binmode(\s-1FH\s0) \- which is in turn defined as doing whatever is
necessary to pass each byte as-is without any translation.  In
particular binmode(\s-1FH\s0) \- and hence \f(CW\*(C`:raw\*(C'\fR \- will now turn off both
\&\s-1CRLF\s0 and \s-1UTF\-8\s0 translation and remove other layers (e.g. :\fIencoding()\fR)
which would modify byte stream.
.IP "\(bu" 4
The current user-visible implementation of pseudo-hashes (the weird
use of the first array element) is deprecated starting from Perl 5.8.0
and will be removed in Perl 5.10.0, and the feature will be
implemented differently.  Not only is the current interface rather
ugly, but the current implementation slows down normal array and hash
use quite noticeably. The \f(CW\*(C`fields\*(C'\fR pragma interface will remain
available.  The \fIrestricted hashes\fR interface is expected to
be the replacement interface (see Hash::Util).  If your existing
programs depends on the underlying implementation, consider using
Class::PseudoHash from \s-1CPAN\s0.
.IP "\(bu" 4
The syntaxes \f(CW\*(C`@a\->[...]\*(C'\fR and  \f(CW\*(C`%h\->{...}\*(C'\fR have now been deprecated.
.IP "\(bu" 4
After years of trying, suidperl is considered to be too complex to
ever be considered truly secure.  The suidperl functionality is likely
to be removed in a future release.
.IP "\(bu" 4
The 5.005 threads model (module \f(CW\*(C`Thread\*(C'\fR) is deprecated and expected
to be removed in Perl 5.10.  Multithreaded code should be migrated to
the new ithreads model (see threads, threads::shared and
perlthrtut).
.IP "\(bu" 4
The long deprecated uppercase aliases for the string comparison
operators (\s-1EQ\s0, \s-1NE\s0, \s-1LT\s0, \s-1LE\s0, \s-1GE\s0, \s-1GT\s0) have now been removed.
.IP "\(bu" 4
The tr///C and tr///U features have been removed and will not return;
the interface was a mistake.  Sorry about that.  For similar
functionality, see pack('U0', ...) and pack('C0', ...). [561]
.IP "\(bu" 4
Earlier Perls treated \*(L"sub foo (@bar)\*(R" as equivalent to \*(L"sub foo (@)\*(R".
The prototypes are now checked better at compile-time for invalid
syntax.  An optional warning is generated (\*(L"Illegal character in
prototype...\*(R")  but this may be upgraded to a fatal error in a future
release.
.IP "\(bu" 4
The \f(CW\*(C`exec LIST\*(C'\fR and \f(CW\*(C`system LIST\*(C'\fR operations now produce warnings on
tainted data and in some future release they will produce fatal errors.
.IP "\(bu" 4
The existing behaviour when localising tied arrays and hashes is wrong,
and will be changed in a future release, so do not rely on the existing
behaviour. See \*(L"Localising Tied Arrays and Hashes Is Broken\*(R".
.SH "Core Enhancements"
.IX Header "Core Enhancements"
.Sh "Unicode Overhaul"
.IX Subsection "Unicode Overhaul"
Unicode in general should be now much more usable than in Perl 5.6.0
(or even in 5.6.1).  Unicode can be used in hash keys, Unicode in
regular expressions should work now, Unicode in tr/// should work now,
Unicode in I/O should work now.  See perluniintro for introduction
and perlunicode for details.
.IP "\(bu" 4
The Unicode Character Database coming with Perl has been upgraded
to Unicode 3.2.0.  For more information, see http://www.unicode.org/ .
[561+] (5.6.1 has \s-1UCD\s0 3.0.1.)
.IP "\(bu" 4
For developers interested in enhancing Perl's Unicode capabilities:
almost all the \s-1UCD\s0 files are included with the Perl distribution in
the \fIlib/unicore\fR subdirectory.  The most notable omission, for space
considerations, is the Unihan database.
.IP "\(bu" 4
The properties \ep{Blank} and \ep{SpacePerl} have been added. \*(L"Blank\*(R" is like
C \fIisblank()\fR, that is, it contains only \*(L"horizontal whitespace\*(R" (the space
character is, the newline isn't), and the \*(L"SpacePerl\*(R" is the Unicode
equivalent of \f(CW\*(C`\es\*(C'\fR (\ep{Space} isn't, since that includes the vertical
tabulator character, whereas \f(CW\*(C`\es\*(C'\fR doesn't.)
.Sp
See \*(L"New Unicode Properties\*(R" earlier in this document for additional
information on changes with Unicode properties.
.Sh "PerlIO is Now The Default"
.IX Subsection "PerlIO is Now The Default"
.IP "\(bu" 4
\&\s-1IO\s0 is now by default done via PerlIO rather than system's \*(L"stdio\*(R".
PerlIO allows \*(L"layers\*(R" to be \*(L"pushed\*(R" onto a file handle to alter the
handle's behaviour.  Layers can be specified at open time via 3\-arg
form of open:
.Sp
.Vb 1
\&   open($fh,\*(Aq>:crlf :utf8\*(Aq, $path) || ...
.Ve
.Sp
or on already opened handles via extended \f(CW\*(C`binmode\*(C'\fR:
.Sp
.Vb 1
\&   binmode($fh,\*(Aq:encoding(iso\-8859\-7)\*(Aq);
.Ve
.Sp
The built-in layers are: unix (low level read/write), stdio (as in
previous Perls), perlio (re-implementation of stdio buffering in a
portable manner), crlf (does \s-1CRLF\s0 <=> \*(L"\en\*(R" translation as on Win32,
but available on any platform).  A mmap layer may be available if
platform supports it (mostly UNIXes).
.Sp
Layers to be applied by default may be specified via the 'open' pragma.
.Sp
See \*(L"Installation and Configuration Improvements\*(R" for the effects
of PerlIO on your architecture name.
.IP "\(bu" 4
If your platform supports \fIfork()\fR, you can use the list form of \f(CW\*(C`open\*(C'\fR
for pipes.  For example:
.Sp
.Vb 1
\&    open KID_PS, "\-|", "ps", "aux" or die $!;
.Ve
.Sp
forks the \fIps\fR\|(1) command (without spawning a shell, as there are more
than three arguments to \fIopen()\fR), and reads its standard output via the
\&\f(CW\*(C`KID_PS\*(C'\fR filehandle.  See perlipc.
.IP "\(bu" 4
File handles can be marked as accepting Perl's internal encoding of Unicode
(\s-1UTF\-8\s0 or UTF-EBCDIC depending on platform) by a pseudo layer \*(L":utf8\*(R" :
.Sp
.Vb 1
\&   open($fh,">:utf8","Uni.txt");
.Ve
.Sp
Note for \s-1EBCDIC\s0 users: the pseudo layer \*(L":utf8\*(R" is erroneously named
for you since it's not \s-1UTF\-8\s0 what you will be getting but instead
UTF-EBCDIC.  See perlunicode, utf8, and
http://www.unicode.org/unicode/reports/tr16/ for more information.
In future releases this naming may change.  See perluniintro
for more information about \s-1UTF\-8\s0.
.IP "\(bu" 4
If your environment variables (\s-1LC_ALL\s0, \s-1LC_CTYPE\s0, \s-1LANG\s0) look like you
want to use \s-1UTF\-8\s0 (any of the variables match \f(CW\*(C`/utf\-?8/i\*(C'\fR), your
\&\s-1STDIN\s0, \s-1STDOUT\s0, \s-1STDERR\s0 handles and the default open layer (see open)
are marked as \s-1UTF\-8\s0.  (This feature, like other new features that
combine Unicode and I/O, work only if you are using PerlIO, but that's
the default.)
.Sp
Note that after this Perl really does assume that everything is \s-1UTF\-8:\s0
for example if some input handle is not, Perl will probably very soon
complain about the input data like this \*(L"Malformed \s-1UTF\-8\s0 ...\*(R" since
any old eight-bit data is not legal \s-1UTF\-8\s0.
.Sp
Note for code authors: if you want to enable your users to use \s-1UTF\-8\s0
as their default encoding  but in your code still have eight-bit I/O streams
(such as images or zip files), you need to explicitly \fIopen()\fR or \fIbinmode()\fR
with \f(CW\*(C`:bytes\*(C'\fR (see \*(L"open\*(R" in perlfunc and \*(L"binmode\*(R" in perlfunc), or you
can just use \f(CW\*(C`binmode(FH)\*(C'\fR (nice for pre\-5.8.0 backward compatibility).
.IP "\(bu" 4
File handles can translate character encodings from/to Perl's internal
Unicode form on read/write via the \*(L":\fIencoding()\fR\*(R" layer.
.IP "\(bu" 4
File handles can be opened to \*(L"in memory\*(R" files held in Perl scalars via:
.Sp
.Vb 1
\&   open($fh,\*(Aq>\*(Aq, \e$variable) || ...
.Ve
.IP "\(bu" 4
Anonymous temporary files are available without need to
\&'use FileHandle' or other module via
.Sp
.Vb 1
\&   open($fh,"+>", undef) || ...
.Ve
.Sp
That is a literal undef, not an undefined value.
.Sh "ithreads"
.IX Subsection "ithreads"
The new interpreter threads (\*(L"ithreads\*(R" for short) implementation of
multithreading, by Arthur Bergman, replaces the old \*(L"5.005 threads\*(R"
implementation.  In the ithreads model any data sharing between
threads must be explicit, as opposed to the model where data sharing
was implicit.  See threads and threads::shared, and
perlthrtut.
.PP
As a part of the ithreads implementation Perl will also use
any necessary and detectable reentrant libc interfaces.
.Sh "Restricted Hashes"
.IX Subsection "Restricted Hashes"
A restricted hash is restricted to a certain set of keys, no keys
outside the set can be added.  Also individual keys can be restricted
so that the key cannot be deleted and the value cannot be changed.
No new syntax is involved: the Hash::Util module is the interface.
.Sh "Safe Signals"
.IX Subsection "Safe Signals"
Perl used to be fragile in that signals arriving at inopportune moments
could corrupt Perl's internal state.  Now Perl postpones handling of
signals until it's safe (between opcodes).
.PP
This change may have surprising side effects because signals no longer
interrupt Perl instantly.  Perl will now first finish whatever it was
doing, like finishing an internal operation (like \fIsort()\fR) or an
external operation (like an I/O operation), and only then look at any
arrived signals (and before starting the next operation).  No more corrupt
internal state since the current operation is always finished first,
but the signal may take more time to get heard.  Note that breaking
out from potentially blocking operations should still work, though.
.Sh "Understanding of Numbers"
.IX Subsection "Understanding of Numbers"
In general a lot of fixing has happened in the area of Perl's
understanding of numbers, both integer and floating point.  Since in
many systems the standard number parsing functions like \f(CW\*(C`strtoul()\*(C'\fR
and \f(CW\*(C`atof()\*(C'\fR seem to have bugs, Perl tries to work around their
deficiencies.  This results hopefully in more accurate numbers.
.PP
Perl now tries internally to use integer values in numeric conversions
and basic arithmetics (+ \- * /) if the arguments are integers, and
tries also to keep the results stored internally as integers.
This change leads to often slightly faster and always less lossy
arithmetics. (Previously Perl always preferred floating point numbers
in its math.)
.Sh "Arrays now always interpolate into double-quoted strings [561]"
.IX Subsection "Arrays now always interpolate into double-quoted strings [561]"
In double-quoted strings, arrays now interpolate, no matter what.  The
behavior in earlier versions of perl 5 was that arrays would interpolate
into strings if the array had been mentioned before the string was
compiled, and otherwise Perl would raise a fatal compile-time error.
In versions 5.000 through 5.003, the error was
.PP
.Vb 1
\&        Literal @example now requires backslash
.Ve
.PP
In versions 5.004_01 through 5.6.0, the error was
.PP
.Vb 1
\&        In string, @example now must be written as \e@example
.Ve
.PP
The idea here was to get people into the habit of writing
\&\f(CW"fred\[e-mail]"\fR when they wanted a literal \f(CW\*(C`@\*(C'\fR sign, just as
they have always written \f(CW"Give me back my \e$5"\fR when they wanted a
literal \f(CW\*(C`$\*(C'\fR sign.
.PP
Starting with 5.6.1, when Perl now sees an \f(CW\*(C`@\*(C'\fR sign in a
double-quoted string, it \fIalways\fR attempts to interpolate an array,
regardless of whether or not the array has been used or declared
already.  The fatal error has been downgraded to an optional warning:
.PP
.Vb 1
\&        Possible unintended interpolation of @example in string
.Ve
.PP