perl5004delta.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.

.PD
Looks for MakeMaker-like \fI'blib'\fR directory structure starting in
\&\fIdir\fR (or current directory) and working back up to five levels of
parent directories.
.Sp
Intended for use on command line with \fB\-M\fR option as a way of testing
arbitrary scripts against an uninstalled version of a package.
.IP "use constant \s-1NAME\s0 => \s-1VALUE\s0" 4
.IX Item "use constant NAME => VALUE"
Provides a convenient interface for creating compile-time constants,
See \*(L"Constant Functions\*(R" in perlsub.
.IP "use locale" 4
.IX Item "use locale"
Tells the compiler to enable (or disable) the use of \s-1POSIX\s0 locales for
builtin operations.
.Sp
When \f(CW\*(C`use locale\*(C'\fR is in effect, the current \s-1LC_CTYPE\s0 locale is used
for regular expressions and case mapping; \s-1LC_COLLATE\s0 for string
ordering; and \s-1LC_NUMERIC\s0 for numeric formatting in printf and sprintf
(but \fBnot\fR in print).  \s-1LC_NUMERIC\s0 is always used in write, since
lexical scoping of formats is problematic at best.
.Sp
Each \f(CW\*(C`use locale\*(C'\fR or \f(CW\*(C`no locale\*(C'\fR affects statements to the end of
the enclosing \s-1BLOCK\s0 or, if not inside a \s-1BLOCK\s0, to the end of the
current file.  Locales can be switched and queried with
\&\fIPOSIX::setlocale()\fR.
.Sp
See perllocale for more information.
.IP "use ops" 4
.IX Item "use ops"
Disable unsafe opcodes, or any named opcodes, when compiling Perl code.
.IP "use vmsish" 4
.IX Item "use vmsish"
Enable VMS-specific language features.  Currently, there are three
VMS-specific features available: 'status', which makes \f(CW$?\fR and
\&\f(CW\*(C`system\*(C'\fR return genuine \s-1VMS\s0 status values instead of emulating \s-1POSIX\s0;
\&'exit', which makes \f(CW\*(C`exit\*(C'\fR take a genuine \s-1VMS\s0 status value instead of
assuming that \f(CW\*(C`exit 1\*(C'\fR is an error; and 'time', which makes all times
relative to the local time zone, in the \s-1VMS\s0 tradition.
.SH "Modules"
.IX Header "Modules"
.Sh "Required Updates"
.IX Subsection "Required Updates"
Though Perl 5.004 is compatible with almost all modules that work
with Perl 5.003, there are a few exceptions:
.PP
.Vb 5
\&    Module   Required Version for Perl 5.004
\&    \-\-\-\-\-\-   \-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
\&    Filter   Filter\-1.12
\&    LWP      libwww\-perl\-5.08
\&    Tk       Tk400.202 (\-w makes noise)
.Ve
.PP
Also, the majordomo mailing list program, version 1.94.1, doesn't work
with Perl 5.004 (nor with perl 4), because it executes an invalid
regular expression.  This bug is fixed in majordomo version 1.94.2.
.Sh "Installation directories"
.IX Subsection "Installation directories"
The \fIinstallperl\fR script now places the Perl source files for
extensions in the architecture-specific library directory, which is
where the shared libraries for extensions have always been.  This
change is intended to allow administrators to keep the Perl 5.004
library directory unchanged from a previous version, without running
the risk of binary incompatibility between extensions' Perl source and
shared libraries.
.Sh "Module information summary"
.IX Subsection "Module information summary"
Brand new modules, arranged by topic rather than strictly
alphabetically:
.PP
.Vb 6
\&    CGI.pm               Web server interface ("Common Gateway Interface")
\&    CGI/Apache.pm        Support for Apache\*(Aqs Perl module
\&    CGI/Carp.pm          Log server errors with helpful context
\&    CGI/Fast.pm          Support for FastCGI (persistent server process)
\&    CGI/Push.pm          Support for server push
\&    CGI/Switch.pm        Simple interface for multiple server types
\&
\&    CPAN                 Interface to Comprehensive Perl Archive Network
\&    CPAN::FirstTime      Utility for creating CPAN configuration file
\&    CPAN::Nox            Runs CPAN while avoiding compiled extensions
\&
\&    IO.pm                Top\-level interface to IO::* classes
\&    IO/File.pm           IO::File extension Perl module
\&    IO/Handle.pm         IO::Handle extension Perl module
\&    IO/Pipe.pm           IO::Pipe extension Perl module
\&    IO/Seekable.pm       IO::Seekable extension Perl module
\&    IO/Select.pm         IO::Select extension Perl module
\&    IO/Socket.pm         IO::Socket extension Perl module
\&
\&    Opcode.pm            Disable named opcodes when compiling Perl code
\&
\&    ExtUtils/Embed.pm    Utilities for embedding Perl in C programs
\&    ExtUtils/testlib.pm  Fixes up @INC to use just\-built extension
\&
\&    FindBin.pm           Find path of currently executing program
\&
\&    Class/Struct.pm      Declare struct\-like datatypes as Perl classes
\&    File/stat.pm         By\-name interface to Perl\*(Aqs builtin stat
\&    Net/hostent.pm       By\-name interface to Perl\*(Aqs builtin gethost*
\&    Net/netent.pm        By\-name interface to Perl\*(Aqs builtin getnet*
\&    Net/protoent.pm      By\-name interface to Perl\*(Aqs builtin getproto*
\&    Net/servent.pm       By\-name interface to Perl\*(Aqs builtin getserv*
\&    Time/gmtime.pm       By\-name interface to Perl\*(Aqs builtin gmtime
\&    Time/localtime.pm    By\-name interface to Perl\*(Aqs builtin localtime
\&    Time/tm.pm           Internal object for Time::{gm,local}time
\&    User/grent.pm        By\-name interface to Perl\*(Aqs builtin getgr*
\&    User/pwent.pm        By\-name interface to Perl\*(Aqs builtin getpw*
\&
\&    Tie/RefHash.pm       Base class for tied hashes with references as keys
\&
\&    UNIVERSAL.pm         Base class for *ALL* classes
.Ve
.Sh "Fcntl"
.IX Subsection "Fcntl"
New constants in the existing Fcntl modules are now supported,
provided that your operating system happens to support them:
.PP
.Vb 3
\&    F_GETOWN F_SETOWN
\&    O_ASYNC O_DEFER O_DSYNC O_FSYNC O_SYNC
\&    O_EXLOCK O_SHLOCK
.Ve
.PP
These constants are intended for use with the Perl operators \fIsysopen()\fR
and \fIfcntl()\fR and the basic database modules like SDBM_File.  For the
exact meaning of these and other Fcntl constants please refer to your
operating system's documentation for \fIfcntl()\fR and \fIopen()\fR.
.PP
In addition, the Fcntl module now provides these constants for use
with the Perl operator \fIflock()\fR:
.PP
.Vb 1
\&        LOCK_SH LOCK_EX LOCK_NB LOCK_UN
.Ve
.PP
These constants are defined in all environments (because where there is
no \fIflock()\fR system call, Perl emulates it).  However, for historical
reasons, these constants are not exported unless they are explicitly
requested with the \*(L":flock\*(R" tag (e.g. \f(CW\*(C`use Fcntl \*(Aq:flock\*(Aq\*(C'\fR).
.Sh "\s-1IO\s0"
.IX Subsection "IO"
The \s-1IO\s0 module provides a simple mechanism to load all the \s-1IO\s0 modules at one
go.  Currently this includes:
.PP
.Vb 5
\&     IO::Handle
\&     IO::Seekable
\&     IO::File
\&     IO::Pipe
\&     IO::Socket
.Ve
.PP
For more information on any of these modules, please see its
respective documentation.
.Sh "Math::Complex"
.IX Subsection "Math::Complex"
The Math::Complex module has been totally rewritten, and now supports
more operations.  These are overloaded:
.PP
.Vb 1
\&     + \- * / ** <=> neg ~ abs sqrt exp log sin cos atan2 "" (stringify)
.Ve
.PP
And these functions are now exported:
.PP
.Vb 11
\&    pi i Re Im arg
\&    log10 logn ln cbrt root
\&    tan
\&    csc sec cot
\&    asin acos atan
\&    acsc asec acot
\&    sinh cosh tanh
\&    csch sech coth
\&    asinh acosh atanh
\&    acsch asech acoth
\&    cplx cplxe
.Ve
.Sh "Math::Trig"
.IX Subsection "Math::Trig"
This new module provides a simpler interface to parts of Math::Complex for
those who need trigonometric functions only for real numbers.
.Sh "DB_File"
.IX Subsection "DB_File"
There have been quite a few changes made to DB_File. Here are a few of
the highlights:
.IP "\(bu" 4
Fixed a handful of bugs.
.IP "\(bu" 4
By public demand, added support for the standard hash function \fIexists()\fR.
.IP "\(bu" 4
Made it compatible with Berkeley \s-1DB\s0 1.86.
.IP "\(bu" 4
Made negative subscripts work with \s-1RECNO\s0 interface.
.IP "\(bu" 4
Changed the default flags from O_RDWR to O_CREAT|O_RDWR and the default
mode from 0640 to 0666.
.IP "\(bu" 4
Made DB_File automatically import the \fIopen()\fR constants (O_RDWR,
O_CREAT etc.) from Fcntl, if available.
.IP "\(bu" 4
Updated documentation.
.PP
Refer to the \s-1HISTORY\s0 section in DB_File.pm for a complete list of
changes. Everything after DB_File 1.01 has been added since 5.003.
.Sh "Net::Ping"
.IX Subsection "Net::Ping"
Major rewrite \- support added for both udp echo and real icmp pings.
.Sh "Object-oriented overrides for builtin operators"
.IX Subsection "Object-oriented overrides for builtin operators"
Many of the Perl builtins returning lists now have
object-oriented overrides.  These are:
.PP
.Vb 9
\&    File::stat
\&    Net::hostent
\&    Net::netent
\&    Net::protoent
\&    Net::servent
\&    Time::gmtime
\&    Time::localtime
\&    User::grent
\&    User::pwent
.Ve
.PP
For example, you can now say
.PP
.Vb 3
\&    use File::stat;
\&    use User::pwent;
\&    $his = (stat($filename)\->st_uid == pwent($whoever)\->pw_uid);
.Ve
.SH "Utility Changes"
.IX Header "Utility Changes"
.Sh "pod2html"
.IX Subsection "pod2html"
.IP "Sends converted \s-1HTML\s0 to standard output" 4
.IX Item "Sends converted HTML to standard output"
The \fIpod2html\fR utility included with Perl 5.004 is entirely new.
By default, it sends the converted \s-1HTML\s0 to its standard output,
instead of writing it to a file like Perl 5.003's \fIpod2html\fR did.
Use the \fB\-\-outfile=FILENAME\fR option to write to a file.
.Sh "xsubpp"
.IX Subsection "xsubpp"
.ie n .IP """void"" XSUBs now default to returning nothing" 4
.el .IP "\f(CWvoid\fR XSUBs now default to returning nothing" 4
.IX Item "void XSUBs now default to returning nothing"
Due to a documentation/implementation bug in previous versions of
Perl, XSUBs with a return type of \f(CW\*(C`void\*(C'\fR have actually been
returning one value.  Usually that value was the \s-1GV\s0 for the \s-1XSUB\s0,
but sometimes it was some already freed or reused value, which would
sometimes lead to program failure.
.Sp
In Perl 5.004, if an \s-1XSUB\s0 is declared as returning \f(CW\*(C`void\*(C'\fR, it
actually returns no value, i.e. an empty list (though there is a
backward-compatibility exception; see below).  If your \s-1XSUB\s0 really
does return an \s-1SV\s0, you should give it a return type of \f(CW\*(C`SV *\*(C'\fR.
.Sp
For backward compatibility, \fIxsubpp\fR tries to guess whether a
\&\f(CW\*(C`void\*(C'\fR \s-1XSUB\s0 is really \f(CW\*(C`void\*(C'\fR or if it wants to return an \f(CW\*(C`SV *\*(C'\fR.
It does so by examining the text of the \s-1XSUB:\s0 if \fIxsubpp\fR finds
what looks like an assignment to \f(CWST(0)\fR, it assumes that the
\&\s-1XSUB\s0's return type is really \f(CW\*(C`SV *\*(C'\fR.
.SH "C Language API Changes"
.IX Header "C Language API Changes"
.ie n .IP """gv_fetchmethod""\fR and \f(CW""perl_call_sv""" 4
.el .IP "\f(CWgv_fetchmethod\fR and \f(CWperl_call_sv\fR" 4
.IX Item "gv_fetchmethod and perl_call_sv"
The \f(CW\*(C`gv_fetchmethod\*(C'\fR function finds a method for an object, just like
in Perl 5.003.  The \s-1GV\s0 it returns may be a method cache entry.
However, in Perl 5.004, method cache entries are not visible to users;
therefore, they can no longer be passed directly to \f(CW\*(C`perl_call_sv\*(C'\fR.
Instead, you should use the \f(CW\*(C`GvCV\*(C'\fR macro on the \s-1GV\s0 to extract its \s-1CV\s0,
and pass the \s-1CV\s0 to \f(CW\*(C`perl_call_sv\*(C'\fR.
.Sp
The most likely symptom of passing the result of \f(CW\*(C`gv_fetchmethod\*(C'\fR to
\&\f(CW\*(C`perl_call_sv\*(C'\fR is Perl's producing an \*(L"Undefined subroutine called\*(R"
error on the \fIsecond\fR call to a given method (since there is no cache
on the first call).
.ie n .IP """perl_eval_pv""" 4
.el .IP "\f(CWperl_eval_pv\fR" 4
.IX Item "perl_eval_pv"
A new function handy for eval'ing strings of Perl code inside C code.
This function returns the value from the eval statement, which can
be used instead of fetching globals from the symbol table.  See
perlguts, perlembed and perlcall for details and examples.
.IP "Extended \s-1API\s0 for manipulating hashes" 4
.IX Item "Extended API for manipulating hashes"
Internal handling of hash keys has changed.  The old hashtable \s-1API\s0 is
still fully supported, and will likely remain so.  The additions to the
\&\s-1API\s0 allow passing keys as \f(CW\*(C`SV*\*(C'\fRs, so that \f(CW\*(C`tied\*(C'\fR hashes can be given
real scalars as keys rather than plain strings (nontied hashes still
can only use strings as keys).  New extensions must use the new hash
access functions and macros if they wish to use \f(CW\*(C`SV*\*(C'\fR keys.  These