=head1 NAME
-perldelta - what's new for perl5.004
+perldelta - what's new for perl v5.6 (as of v5.005_58)
=head1 DESCRIPTION
-This document describes differences between the 5.003 release (as
-documented in I<Programming Perl>, second edition--the Camel Book) and
-this one.
+This is an unsupported alpha release, meant for intrepid Perl developers
+only. The included sources may not even build correctly on some platforms.
+Subscribing to perl5-porters is the best way to monitor and contribute
+to the progress of development releases (see www.perl.org for info).
-=head1 Supported Environments
+This document describes differences between the 5.005 release and this one.
-Perl5.004 builds out of the box on Unix, Plan 9, LynxOS, VMS, OS/2,
-QNX, AmigaOS, and Windows NT. Perl runs on Windows 95 as well, but it
-cannot be built there, for lack of a reasonable command interpreter.
+=head1 Incompatible Changes
-=head1 Core Changes
-
-Most importantly, many bugs were fixed, including several security
-problems. See the F<Changes> file in the distribution for details.
-
-=head2 List assignment to %ENV works
-
-C<%ENV = ()> and C<%ENV = @list> now work as expected (except on VMS
-where it generates a fatal error).
-
-=head2 "Can't locate Foo.pm in @INC" error now lists @INC
-
-=head2 Compilation option: Binary compatibility with 5.003
-
-There is a new Configure question that asks if you want to maintain
-binary compatibility with Perl 5.003. If you choose binary
-compatibility, you do not have to recompile your extensions, but you
-might have symbol conflicts if you embed Perl in another application,
-just as in the 5.003 release. By default, binary compatibility
-is preserved at the expense of symbol table pollution.
-
-=head2 $PERL5OPT environment variable
-
-You may now put Perl options in the $PERL5OPT environment variable.
-Unless Perl is running with taint checks, it will interpret this
-variable as if its contents had appeared on a "#!perl" line at the
-beginning of your script, except that hyphens are optional. PERL5OPT
-may only be used to set the following switches: B<-[DIMUdmw]>.
-
-=head2 Limitations on B<-M>, B<-m>, and B<-T> options
-
-The C<-M> and C<-m> options are no longer allowed on the C<#!> line of
-a script. If a script needs a module, it should invoke it with the
-C<use> pragma.
-
-The B<-T> option is also forbidden on the C<#!> line of a script,
-unless it was present on the Perl command line. Due to the way C<#!>
-works, this usually means that B<-T> must be in the first argument.
-Thus:
-
- #!/usr/bin/perl -T -w
-
-will probably work for an executable script invoked as C<scriptname>,
-while:
-
- #!/usr/bin/perl -w -T
-
-will probably fail under the same conditions. (Non-Unix systems will
-probably not follow this rule.) But C<perl scriptname> is guaranteed
-to fail, since then there is no chance of B<-T> being found on the
-command line before it is found on the C<#!> line.
-
-=head2 More precise warnings
-
-If you removed the B<-w> option from your Perl 5.003 scripts because it
-made Perl too verbose, we recommend that you try putting it back when
-you upgrade to Perl 5.004. Each new perl version tends to remove some
-undesirable warnings, while adding new warnings that may catch bugs in
-your scripts.
-
-=head2 Deprecated: Inherited C<AUTOLOAD> for non-methods
-
-Before Perl 5.004, C<AUTOLOAD> functions were looked up as methods
-(using the C<@ISA> hierarchy), even when the function to be autoloaded
-was called as a plain function (e.g. C<Foo::bar()>), not a method
-(e.g. C<Foo-E<gt>bar()> or C<$obj-E<gt>bar()>).
-
-Perl 5.005 will use method lookup only for methods' C<AUTOLOAD>s.
-However, there is a significant base of existing code that may be using
-the old behavior. So, as an interim step, Perl 5.004 issues an optional
-warning when a non-method uses an inherited C<AUTOLOAD>.
-
-The simple rule is: Inheritance will not work when autoloading
-non-methods. The simple fix for old code is: In any module that used to
-depend on inheriting C<AUTOLOAD> for non-methods from a base class named
-C<BaseClass>, execute C<*AUTOLOAD = \&BaseClass::AUTOLOAD> during startup.
-
-=head2 Previously deprecated %OVERLOAD is no longer usable
-
-Using %OVERLOAD to define overloading was deprecated in 5.003.
-Overloading is now defined using the overload pragma. %OVERLOAD is
-still used internally but should not be used by Perl scripts. See
-L<overload> for more details.
-
-=head2 Subroutine arguments created only when they're modified
-
-In Perl 5.004, nonexistent array and hash elements used as subroutine
-parameters are brought into existence only if they are actually
-assigned to (via C<@_>).
-
-Earlier versions of Perl vary in their handling of such arguments.
-Perl versions 5.002 and 5.003 always brought them into existence.
-Perl versions 5.000 and 5.001 brought them into existence only if
-they were not the first argument (which was almost certainly a bug).
-Earlier versions of Perl never brought them into existence.
-
-For example, given this code:
-
- undef @a; undef %a;
- sub show { print $_[0] };
- sub change { $_[0]++ };
- show($a[2]);
- change($a{b});
-
-After this code executes in Perl 5.004, $a{b} exists but $a[2] does
-not. In Perl 5.002 and 5.003, both $a{b} and $a[2] would have existed
-(but $a[2]'s value would have been undefined).
-
-=head2 Group vector changeable with C<$)>
-
-The C<$)> special variable has always (well, in Perl 5, at least)
-reflected not only the current effective group, but also the group list
-as returned by the C<getgroups()> C function (if there is one).
-However, until this release, there has not been a way to call the
-C<setgroups()> C function from Perl.
-
-In Perl 5.004, assigning to C<$)> is exactly symmetrical with examining
-it: The first number in its string value is used as the effective gid;
-if there are any numbers after the first one, they are passed to the
-C<setgroups()> C function (if there is one).
-
-=head2 Fixed parsing of $$<digit>, &$<digit>, etc.
-
-Perl versions before 5.004 misinterpreted any type marker followed by
-"$" and a digit. For example, "$$0" was incorrectly taken to mean
-"${$}0" instead of "${$0}". This bug is (mostly) fixed in Perl 5.004.
-
-However, the developers of Perl 5.004 could not fix this bug completely,
-because at least two widely-used modules depend on the old meaning of
-"$$0" in a string. So Perl 5.004 still interprets "$$<digit>" in the
-old (broken) way inside strings; but it generates this message as a
-warning. And in Perl 5.005, this special treatment will cease.
+=head2 Perl Source Incompatibilities
-=head2 No resetting of $. on implicit close
+TODO
-The documentation for Perl 5.0 has always stated that C<$.> is I<not>
-reset when an already-open file handle is reopened with no intervening
-call to C<close>. Due to a bug, perl versions 5.000 through 5.003
-I<did> reset C<$.> under that circumstance; Perl 5.004 does not.
+=head2 C Source Incompatibilities
-=head2 C<wantarray> may return undef
+=over 4
-The C<wantarray> operator returns true if a subroutine is expected to
-return a list, and false otherwise. In Perl 5.004, C<wantarray> can
-also return the undefined value if a subroutine's return value will
-not be used at all, which allows subroutines to avoid a time-consuming
-calculation of a return value if it isn't going to be used.
+=item C<PERL_POLLUTE>
-=head2 Changes to tainting checks
+Release 5.005 grandfathered old global symbol names by providing preprocessor
+macros for extension source compatibility. As of release 5.6, these
+preprocessor definitions are not available by default. You need to explicitly
+compile perl with C<-DPERL_POLLUTE> to get these definitions. For
+extensions still using the old symbols, this option can be
+specified via MakeMaker:
-A bug in previous versions may have failed to detect some insecure
-conditions when taint checks are turned on. (Taint checks are used
-in setuid or setgid scripts, or when explicitly turned on with the
-C<-T> invocation option.) Although it's unlikely, this may cause a
-previously-working script to now fail -- which should be construed
-as a blessing, since that indicates a potentially-serious security
-hole was just plugged.
+ perl Makefile.PL POLLUTE=1
-The new restrictions when tainting include:
+=item C<PERL_IMPLICIT_CONTEXT>
-=over
-
-=item No glob() or <*>
-
-These operators may spawn the C shell (csh), which cannot be made
-safe. This restriction will be lifted in a future version of Perl
-when globbing is implemented without the use of an external program.
-
-=item No spawning if tainted $CDPATH, $ENV, $BASH_ENV
-
-These environment variables may alter the behavior of spawned programs
-(especially shells) in ways that subvert security. So now they are
-treated as dangerous, in the manner of $IFS and $PATH.
+This new build option provides a set of macros for all API functions
+such that an implicit interpreter/thread context argument is passed to
+every API function. As a result of this, something like C<sv_setsv(foo,bar)>
+amounts to a macro invocation that actually translates to something like
+C<Perl_sv_setsv(my_perl,foo,bar)>. While this is generally expected
+to not have any significant source compatibility issues, the difference
+between a macro and a real function call will need to be considered.
-=item No spawning if tainted $TERM doesn't look like a terminal name
+This means that there B<is> a source compatibility issue as a result of
+this if your extensions attempt to use pointers to any of the Perl API
+functions.
-Some termcap libraries do unsafe things with $TERM. However, it would be
-unnecessarily harsh to treat all $TERM values as unsafe, since only shell
-metacharacters can cause trouble in $TERM. So a tainted $TERM is
-considered to be safe if it contains only alphanumerics, underscores,
-dashes, and colons, and unsafe if it contains other characters (including
-whitespace).
+Note that the above issue is not relevant to the default build of
+Perl, whose interfaces continue to match those of prior versions
+(but subject to the other options described here).
-=back
-
-=head2 New Opcode module and revised Safe module
-
-A new Opcode module supports the creation, manipulation and
-application of opcode masks. The revised Safe module has a new API
-and is implemented using the new Opcode module. Please read the new
-Opcode and Safe documentation.
+For testing purposes, the 5.005_58 release automatically enables
+PERL_IMPLICIT_CONTEXT whenever Perl is built with -Dusethreads or
+-Dusemultiplicity.
-=head2 Embedding improvements
+See L<perlguts/"The Perl API"> for detailed information on the
+ramifications of building Perl using this option.
-In older versions of Perl it was not possible to create more than one
-Perl interpreter instance inside a single process without leaking like a
-sieve and/or crashing. The bugs that caused this behavior have all been
-fixed. However, you still must take care when embedding Perl in a C
-program. See the updated perlembed manpage for tips on how to manage
-your interpreters.
+=item C<PERL_POLLUTE_MALLOC>
-=head2 Internal change: FileHandle class based on IO::* classes
+Enabling Perl's malloc in release 5.005 and earlier caused
+the namespace of system versions of the malloc family of functions to
+be usurped by the Perl versions, since by default they used the
+same names.
-File handles are now stored internally as type IO::Handle. The
-FileHandle module is still supported for backwards compatibility, but
-it is now merely a front end to the IO::* modules -- specifically,
-IO::Handle, IO::Seekable, and IO::File. We suggest, but do not
-require, that you use the IO::* modules in new code.
+Besides causing problems on platforms that do not allow these functions to
+be cleanly replaced, this also meant that the system versions could not
+be called in programs that used Perl's malloc. Previous versions of Perl
+have allowed this behaviour to be suppressed with the HIDEMYMALLOC and
+EMBEDMYMALLOC preprocessor definitions.
-In harmony with this change, C<*GLOB{FILEHANDLE}> is now just a
-backward-compatible synonym for C<*GLOB{IO}>.
+As of release 5.6, Perl's malloc family of functions have default names
+distinct from the system versions. You need to explicitly compile perl with
+C<-DPERL_POLLUTE_MALLOC> to get the older behaviour. HIDEMYMALLOC
+and EMBEDMYMALLOC have no effect, since the behaviour they enabled is now
+the default.
-=head2 Internal change: PerlIO abstraction interface
+Note that these functions do B<not> constitute Perl's memory allocation API.
+See L<perlguts/"Memory Allocation"> for further information about that.
-It is now possible to build Perl with AT&T's sfio IO package
-instead of stdio. See L<perlapio> for more details, and
-the F<INSTALL> file for how to use it.
+=item C<PL_na> and C<dTHR> Issues
-=head2 New and changed syntax
-
-=over
-
-=item $coderef->(PARAMS)
-
-A subroutine reference may now be suffixed with an arrow and a
-(possibly empty) parameter list. This syntax denotes a call of the
-referenced subroutine, with the given parameters (if any).
-
-This new syntax follows the pattern of S<C<$hashref-E<gt>{FOO}>> and
-S<C<$aryref-E<gt>[$foo]>>: You may now write S<C<&$subref($foo)>> as
-S<C<$subref-E<gt>($foo)>>. All of these arrow terms may be chained;
-thus, S<C<&{$table-E<gt>{FOO}}($bar)>> may now be written
-S<C<$table-E<gt>{FOO}-E<gt>($bar)>>.
+The C<PL_na> global is now thread local, so a C<dTHR> declaration is needed
+in the scope in which the global appears. XSUBs should handle this automatically,
+but if you have used C<PL_na> in support functions, you either need to
+change the C<PL_na> to a local variable (which is recommended), or put in
+a C<dTHR>.
=back
-=head2 New and changed builtin constants
+=head2 Compatible C Source API Changes
=over
-=item __PACKAGE__
-
-The current package name at compile time, or the undefined value if
-there is no current package (due to a C<package;> directive). Like
-C<__FILE__> and C<__LINE__>, C<__PACKAGE__> does I<not> interpolate
-into strings.
-
-=back
-
-=head2 New and changed builtin variables
-
-=over
+=item C<PATCHLEVEL> is now C<PERL_VERSION>
-=item $^E
+The cpp macros C<PERL_REVISION>, C<PERL_VERSION>, and C<PERL_SUBVERSION>
+are now available by default from perl.h, and reflect the base revision,
+patchlevel, and subversion respectively. C<PERL_REVISION> had no
+prior equivalent, while C<PERL_VERSION> and C<PERL_SUBVERSION> were
+previously available as C<PATCHLEVEL> and C<SUBVERSION>.
-Extended error message on some platforms. (Also known as
-$EXTENDED_OS_ERROR if you C<use English>).
-
-=item $^H
-
-The current set of syntax checks enabled by C<use strict>. See the
-documentation of C<strict> for more details. Not actually new, but
-newly documented.
-Because it is intended for internal use by Perl core components,
-there is no C<use English> long name for this variable.
-
-=item $^M
-
-By default, running out of memory it is not trappable. However, if
-compiled for this, Perl may use the contents of C<$^M> as an emergency
-pool after die()ing with this message. Suppose that your Perl were
-compiled with -DEMERGENCY_SBRK and used Perl's malloc. Then
-
- $^M = 'a' x (1<<16);
-
-would allocate a 64K buffer for use when in emergency.
-See the F<INSTALL> file for information on how to enable this option.
-As a disincentive to casual use of this advanced feature,
-there is no C<use English> long name for this variable.
+The new names cause less pollution of the B<cpp> namespace and reflect what
+the numbers have come to stand for in common practice. For compatibility,
+the old names are still supported when F<patchlevel.h> is explicitly
+included (as required before), so there is no source incompatibility
+from the change.
=back
-=head2 New and changed builtin functions
-
-=over
-
-=item delete on slices
-
-This now works. (e.g. C<delete @ENV{'PATH', 'MANPATH'}>)
-
-=item flock
-
-is now supported on more platforms, prefers fcntl to lockf when
-emulating, and always flushes before (un)locking.
-
-=item printf and sprintf
-
-Perl now implements these functions itself; it doesn't use the C
-library function sprintf() any more, except for floating-point
-numbers, and even then only known flags are allowed. As a result, it
-is now possible to know which conversions and flags will work, and
-what they will do.
-
-The new conversions in Perl's sprintf() are:
-
- %i a synonym for %d
- %p a pointer (the address of the Perl value, in hexadecimal)
- %n special: *stores* the number of characters output so far
- into the next variable in the parameter list
-
-The new flags that go between the C<%> and the conversion are:
-
- # prefix octal with "0", hex with "0x"
- h interpret integer as C type "short" or "unsigned short"
- V interpret integer as Perl's standard integer type
-
-Also, where a number would appear in the flags, an asterisk ("*") may
-be used instead, in which case Perl uses the next item in the
-parameter list as the given number (that is, as the field width or
-precision). If a field width obtained through "*" is negative, it has
-the same effect as the '-' flag: left-justification.
-
-See L<perlfunc/sprintf> for a complete list of conversion and flags.
-
-=item keys as an lvalue
-
-As an lvalue, C<keys> allows you to increase the number of hash buckets
-allocated for the given hash. This can gain you a measure of efficiency if
-you know the hash is going to get big. (This is similar to pre-extending
-an array by assigning a larger number to $#array.) If you say
-
- keys %hash = 200;
-
-then C<%hash> will have at least 200 buckets allocated for it. These
-buckets will be retained even if you do C<%hash = ()>; use C<undef
-%hash> if you want to free the storage while C<%hash> is still in scope.
-You can't shrink the number of buckets allocated for the hash using
-C<keys> in this way (but you needn't worry about doing this by accident,
-as trying has no effect).
-
-=item my() in Control Structures
-
-You can now use my() (with or without the parentheses) in the control
-expressions of control structures such as:
-
- while (defined(my $line = <>)) {
- $line = lc $line;
- } continue {
- print $line;
- }
-
- if ((my $answer = <STDIN>) =~ /^y(es)?$/i) {
- user_agrees();
- } elsif ($answer =~ /^n(o)?$/i) {
- user_disagrees();
- } else {
- chomp $answer;
- die "`$answer' is neither `yes' nor `no'";
- }
-
-Also, you can declare a foreach loop control variable as lexical by
-preceding it with the word "my". For example, in:
-
- foreach my $i (1, 2, 3) {
- some_function();
- }
-
-$i is a lexical variable, and the scope of $i extends to the end of
-the loop, but not beyond it.
-
-Note that you still cannot use my() on global punctuation variables
-such as $_ and the like.
-
-=item pack() and unpack()
-
-A new format 'w' represents a BER compressed integer (as defined in
-ASN.1). Its format is a sequence of one or more bytes, each of which
-provides seven bits of the total value, with the most significant
-first. Bit eight of each byte is set, except for the last byte, in
-which bit eight is clear.
-
-Both pack() and unpack() now fail when their templates contain invalid
-types. (Invalid types used to be ignored.)
-
-=item sysseek()
-
-The new sysseek() operator is a variant of seek() that sets and gets the
-file's system read/write position, using the lseek(2) system call. It is
-the only reliable way to seek before using sysread() or syswrite(). Its
-return value is the new position, or the undefined value on failure.
-
-=item use VERSION
-
-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. Because C<use> occurs at compile time, this check happens
-immediately during the compilation process, unlike C<require VERSION>,
-which waits until runtime for the check. 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.)
-
-=item use Module VERSION LIST
-
-If the VERSION argument is present between Module and LIST, then the
-C<use> will call the VERSION method in class Module with the given
-version as an argument. The default VERSION method, inherited from
-the UNIVERSAL class, croaks if the given version is larger than the
-value of the variable $Module::VERSION. (Note that there is not a
-comma after VERSION!)
-
-This version-checking mechanism is similar to the one currently used
-in the Exporter module, but it is faster and can be used with modules
-that don't use the Exporter. It is the recommended method for new
-code.
-
-=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 or the name of the
-function whose prototype you want to retrieve.
-(Not actually new; just never documented before.)
-
-=item srand
-
-The default seed for C<srand>, which used to be C<time>, has been changed.
-Now it's a heady mix of difficult-to-predict system-dependent values,
-which should be sufficient for most everyday purposes.
-
-Previous to version 5.004, calling C<rand> without first calling C<srand>
-would yield the same sequence of random numbers on most or all machines.
-Now, when perl sees that you're calling C<rand> and haven't yet called
-C<srand>, it calls C<srand> with the default seed. You should still call
-C<srand> manually if your code might ever be run on a pre-5.004 system,
-of course, or if you want a seed other than the default.
-
-=item $_ as Default
-
-Functions documented in the Camel to default to $_ now in
-fact do, and all those that do are so documented in L<perlfunc>.
-
-=item C<m//gc> does not reset search position on failure
-
-The C<m//g> match iteration construct has always reset its target
-string's search position (which is visible through the C<pos> operator)
-when a match fails; as a result, the next C<m//g> match after a failure
-starts again at the beginning of the string. With Perl 5.004, this
-reset may be disabled by adding the "c" (for "continue") modifier,
-i.e. C<m//gc>. This feature, in conjunction with the C<\G> zero-width
-assertion, makes it possible to chain matches together. See L<perlop>
-and L<perlre>.
-
-=item C<m//x> ignores whitespace before ?*+{}
-
-The C<m//x> construct has always been intended to ignore all unescaped
-whitespace. However, before Perl 5.004, whitespace had the effect of
-escaping repeat modifiers like "*" or "?"; for example, C</a *b/x> was
-(mis)interpreted as C</a\*b/x>. This bug has been fixed in 5.004.
-
-=item nested C<sub{}> closures work now
-
-Prior to the 5.004 release, nested anonymous functions didn't work
-right. They do now.
-
-=item formats work right on changing lexicals
-
-Just like anonymous functions that contain lexical variables
-that change (like a lexical index variable for a C<foreach> loop),
-formats now work properly. For example, this silently failed
-before (printed only zeros), but is fine now:
-
- my $i;
- foreach $i ( 1 .. 10 ) {
- write;
- }
- format =
- my i is @#
- $i
- .
-
-=back
-
-=head2 New builtin methods
-
-The C<UNIVERSAL> package automatically contains the following methods that
-are inherited by all other classes:
-
-=over
-
-=item isa(CLASS)
-
-C<isa> returns I<true> if its object is blessed into a subclass of C<CLASS>
-
-C<isa> is also exportable and can be called as a sub with two arguments. This
-allows the ability to check what a reference points to. Example:
-
- use UNIVERSAL qw(isa);
-
- if(isa($ref, 'ARRAY')) {
- ...
- }
-
-=item can(METHOD)
-
-C<can> checks to see if its object has a method called C<METHOD>,
-if it does then a reference to the sub is returned; if it does not then
-I<undef> is returned.
-
-=item VERSION( [NEED] )
-
-C<VERSION> returns the version number of the class (package). If the
-NEED argument is given then it will check that the current version (as
-defined by the $VERSION variable in the given package) not less than
-NEED; it will die if this is not the case. This method is normally
-called as a class method. This method is called automatically by the
-C<VERSION> form of C<use>.
-
- use A 1.2 qw(some imported subs);
- # implies:
- A->VERSION(1.2);
-
-=back
-
-B<NOTE:> C<can> directly uses Perl's internal code for method lookup, and
-C<isa> uses a very similar method and caching strategy. This may cause
-strange effects if the Perl code dynamically changes @ISA in any package.
-
-You may add other methods to the UNIVERSAL class via Perl or XS code.
-You do not need to C<use UNIVERSAL> in order to make these methods
-available to your program. This is necessary only if you wish to
-have C<isa> available as a plain subroutine in the current package.
-
-=head2 TIEHANDLE now supported
-
-See L<perltie> for other kinds of tie()s.
-
-=over
-
-=item TIEHANDLE classname, LIST
-
-This is the constructor for the class. That means it is expected to
-return an object of some sort. The reference can be used to
-hold some internal information.
-
- sub TIEHANDLE {
- print "<shout>\n";
- my $i;
- return bless \$i, shift;
- }
-
-=item PRINT this, LIST
-
-This method will be triggered every time the tied handle is printed to.
-Beyond its self reference it also expects the list that was passed to
-the print function.
-
- sub PRINT {
- $r = shift;
- $$r++;
- return print join( $, => map {uc} @_), $\;
- }
-
-=item PRINTF this, LIST
-
-This method will be triggered every time the tied handle is printed to
-with the C<printf()> function.
-Beyond its self reference it also expects the format and list that was
-passed to the printf function.
-
- sub PRINTF {
- shift;
- my $fmt = shift;
- print sprintf($fmt, @_)."\n";
- }
-
-=item READ this LIST
-
-This method will be called when the handle is read from via the C<read>
-or C<sysread> functions.
-
- sub READ {
- $r = shift;
- my($buf,$len,$offset) = @_;
- print "READ called, \$buf=$buf, \$len=$len, \$offset=$offset";
- }
-
-=item READLINE this
-
-This method will be called when the handle is read from. The method
-should return undef when there is no more data.
-
- sub READLINE {
- $r = shift;
- return "PRINT called $$r times\n"
- }
-
-=item GETC this
+=head2 Binary Incompatibilities
-This method will be called when the C<getc> function is called.
+The default build of this release can be made binary compatible with the
+5.005 release or its maintenance versions. Add -DPERL_BINCOMPAT_5005
+to ccflags in config.sh to achieve this. See INSTALL for further
+information about adding build flags to config.sh.
- sub GETC { print "Don't GETC, Get Perl"; return "a"; }
+The usethreads or usemultiplicity builds are B<not> binary compatible
+with the corresponding builds in 5.005.
-=item DESTROY this
-
-As with the other types of ties, this method will be called when the
-tied handle is about to be destroyed. This is useful for debugging and
-possibly for cleaning up.
-
- sub DESTROY {
- print "</shout>\n";
- }
-
-=back
-
-=head2 Malloc enhancements
-
-Four new compilation flags are recognized by malloc.c. (They have no
-effect if perl is compiled with system malloc().)
-
-=over
-
-=item -DDEBUGGING_MSTATS
-
-If perl is compiled with C<DEBUGGING_MSTATS> defined, you can print
-memory statistics at runtime by running Perl thusly:
-
- env PERL_DEBUG_MSTATS=2 perl your_script_here
-
-The value of 2 means to print statistics after compilation and on
-exit; with a value of 1, the statistics ares printed only on exit.
-(If you want the statistics at an arbitrary time, you'll need to
-install the optional module Devel::Peek.)
-
-=item -DEMERGENCY_SBRK
-
-If this macro is defined, running out of memory need not be a fatal
-error: a memory pool can allocated by assigning to the special
-variable C<$^M>. See L<"$^M">.
-
-=item -DPACK_MALLOC
-
-Perl memory allocation is by bucket with sizes close to powers of two.
-Because of these malloc overhead may be big, especially for data of
-size exactly a power of two. If C<PACK_MALLOC> is defined, perl uses
-a slightly different algorithm for small allocations (up to 64 bytes
-long), which makes it possible to have overhead down to 1 byte for
-allocations which are powers of two (and appear quite often).
-
-Expected memory savings (with 8-byte alignment in C<alignbytes>) is
-about 20% for typical Perl usage. Expected slowdown due to additional
-malloc overhead is in fractions of a percent (hard to measure, because
-of the effect of saved memory on speed).
-
-=item -DTWO_POT_OPTIMIZE
-
-Similarly to C<PACK_MALLOC>, this macro improves allocations of data
-with size close to a power of two; but this works for big allocations
-(starting with 16K by default). Such allocations are typical for big
-hashes and special-purpose scripts, especially image processing.
-
-On recent systems, the fact that perl requires 2M from system for 1M
-allocation will not affect speed of execution, since the tail of such
-a chunk is not going to be touched (and thus will not require real
-memory). However, it may result in a premature out-of-memory error.
-So if you will be manipulating very large blocks with sizes close to
-powers of two, it would be wise to define this macro.
-
-Expected saving of memory is 0-100% (100% in applications which
-require most memory in such 2**n chunks); expected slowdown is
-negligible.
-
-=back
-
-=head2 Miscellaneous efficiency enhancements
-
-Functions that have an empty prototype and that do nothing but return
-a fixed value are now inlined (e.g. C<sub PI () { 3.14159 }>).
-
-Each unique hash key is only allocated once, no matter how many hashes
-have an entry with that key. So even if you have 100 copies of the
-same hash, the hash keys never have to be reallocated.
-
-=head1 Support for More Operating Systems
-
-Support for the following operating systems is new in Perl 5.004.
-
-=head2 Win32
-
-Perl 5.004 now includes support for building a "native" perl under
-Windows NT, using the Microsoft Visual C++ compiler (versions 2.0
-and above) or the Borland C++ compiler (versions 5.02 and above).
-The resulting perl can be used under Windows 95 (if it
-is installed in the same directory locations as it got installed
-in Windows NT). This port includes support for perl extension
-building tools like L<MakeMaker> and L<h2xs>, so that many extensions
-available on the Comprehensive Perl Archive Network (CPAN) can now be
-readily built under Windows NT. See http://www.perl.com/ for more
-information on CPAN, and L<README.win32> for more details on how to
-get started with building this port.
-
-There is also support for building perl under the Cygwin32 environment.
-Cygwin32 is a set of GNU tools that make it possible to compile and run
-many UNIX programs under Windows NT by providing a mostly UNIX-like
-interface for compilation and execution. See L<README.cygwin32> for
-more details on this port, and how to obtain the Cygwin32 toolkit.
-
-=head2 Plan 9
-
-See L<README.plan9>.
-
-=head2 QNX
-
-See L<README.qnx>.
-
-=head2 AmigaOS
-
-See L<README.amigaos>.
-
-=head1 Pragmata
-
-Six new pragmatic modules exist:
-
-=over
-
-=item use autouse MODULE => qw(sub1 sub2 sub3)
-
-Defers C<require MODULE> until someone calls one of the specified
-subroutines (which must be exported by MODULE). This pragma should be
-used with caution, and only when necessary.
-
-=item use blib
-
-=item use blib 'dir'
-
-Looks for MakeMaker-like I<'blib'> directory structure starting in
-I<dir> (or current directory) and working back up to five levels of
-parent directories.
+=head1 Core Changes
-Intended for use on command line with B<-M> option as a way of testing
-arbitrary scripts against an uninstalled version of a package.
+=head2 Unicode and UTF-8 support
-=item use constant NAME => VALUE
+Perl can optionally use UTF-8 as its internal representation for character
+strings. The C<use utf8> pragma enables this support in the current lexical
+scope. See L<utf8> for more information.
-Provides a convenient interface for creating compile-time constants,
-See L<perlsub/"Constant Functions">.
+=head2 Lexically scoped warning categories
-=item use locale
+You can now control the granularity of warnings emitted by perl at a finer
+level using the C<use warning> pragma. See L<warning> and L<perllexwarn>
+for details.
-Tells the compiler to enable (or disable) the use of POSIX locales for
-builtin operations.
+=head2 Binary numbers supported
-When C<use locale> is in effect, the current LC_CTYPE locale is used
-for regular expressions and case mapping; LC_COLLATE for string
-ordering; and LC_NUMERIC for numeric formating in printf and sprintf
-(but B<not> in print). LC_NUMERIC is always used in write, since
-lexical scoping of formats is problematic at best.
+Binary numbers are now supported as literals, in s?printf formats, and
+C<oct()>:
-Each C<use locale> or C<no locale> affects statements to the end of
-the enclosing BLOCK or, if not inside a BLOCK, to the end of the
-current file. Locales can be switched and queried with
-POSIX::setlocale().
+ $answer = 0b101010;
+ printf "The answer is: %b\n", oct("0b101010");
-See L<perllocale> for more information.
+=head2 syswrite() ease-of-use
-=item use ops
+The length argument of C<syswrite()> is now optional.
-Disable unsafe opcodes, or any named opcodes, when compiling Perl code.
+=head2 64-bit support
-=item use vmsish
+Better 64-bit support -- but full support still a distant goal. One
+must Configure with -Duse64bits to get Configure to probe for the
+extent of 64-bit support. Depending on the platform (hints file) more
+or less 64-awareness becomes available. As of 5.005_54 at least
+somewhat 64-bit aware platforms are HP-UX 11 or better, Solaris 2.6 or
+better, IRIX 6.2 or better. Naturally 64-bit platforms like Digital
+Unix and UNICOS also have 64-bit support.
-Enable VMS-specific language features. Currently, there are three
-VMS-specific features available: 'status', which makes C<$?> and
-C<system> return genuine VMS status values instead of emulating POSIX;
-'exit', which makes C<exit> take a genuine VMS status value instead of
-assuming that C<exit 1> is an error; and 'time', which makes all times
-relative to the local time zone, in the VMS tradition.
+=head2 Better syntax checks on parenthesized unary operators
-=back
+Expressions such as:
-=head1 Modules
+ print defined(&foo,&bar,&baz);
+ print uc("foo","bar","baz");
+ undef($foo,&bar);
-=head2 Required Updates
+used to be accidentally allowed in earlier versions, and produced
+unpredictable behaviour. Some produced ancillary warnings
+when used in this way; others silently did the wrong thing.
-Though Perl 5.004 is compatible with almost all modules that work
-with Perl 5.003, there are a few exceptions:
+The parenthesized forms of most unary operators that expect a single
+argument now ensure that they are not called with more than one
+argument, making the cases shown above syntax errors. The usual
+behaviour of:
- Module Required Version for Perl 5.004
- ------ -------------------------------
- Filter Filter-1.12
- LWP libwww-perl-5.08
- Tk Tk400.202 (-w makes noise)
+ print defined &foo, &bar, &baz;
+ print uc "foo", "bar", "baz";
+ undef $foo, &bar;
-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.
+remains unchanged. See L<perlop>.
-=head2 Installation directories
+=head2 POSIX character class syntax [: :] supported
-The I<installperl> 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.
+For example to match alphabetic characters use /[[:alpha:]]/.
+See L<perlre> for details.
-=head2 Module information summary
+=head2 Improved C<qw//> operator
-Brand new modules, arranged by topic rather than strictly
-alphabetically:
+The C<qw//> operator is now evaluated at compile time into a true list
+instead of being replaced with a run time call to C<split()>. This
+removes the confusing misbehaviour of C<qw//> in scalar context, which
+had inherited that behaviour from split().
- CGI.pm Web server interface ("Common Gateway Interface")
- CGI/Apache.pm Support for Apache's 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
+Thus:
- CPAN Interface to Comprehensive Perl Archive Network
- CPAN::FirstTime Utility for creating CPAN configuration file
- CPAN::Nox Runs CPAN while avoiding compiled extensions
+ $foo = ($bar) = qw(a b c); print "$foo|$bar\n";
- 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
+now correctly prints "3|a", instead of "2|a".
- Opcode.pm Disable named opcodes when compiling Perl code
+=head2 pack() format 'Z' supported
- ExtUtils/Embed.pm Utilities for embedding Perl in C programs
- ExtUtils/testlib.pm Fixes up @INC to use just-built extension
+The new format type 'Z' is useful for packing and unpacking null-terminated
+strings. See L<perlfunc/"pack">.
- FindBin.pm Find path of currently executing program
+=head2 pack() format modifier '!' supported
- Class/Struct.pm Declare struct-like datatypes as Perl classes
- File/stat.pm By-name interface to Perl's builtin stat
- Net/hostent.pm By-name interface to Perl's builtin gethost*
- Net/netent.pm By-name interface to Perl's builtin getnet*
- Net/protoent.pm By-name interface to Perl's builtin getproto*
- Net/servent.pm By-name interface to Perl's builtin getserv*
- Time/gmtime.pm By-name interface to Perl's builtin gmtime
- Time/localtime.pm By-name interface to Perl's builtin localtime
- Time/tm.pm Internal object for Time::{gm,local}time
- User/grent.pm By-name interface to Perl's builtin getgr*
- User/pwent.pm By-name interface to Perl's builtin getpw*
+The new format type modifier '!' is useful for packing and unpacking
+native shorts, ints, and longs. See L<perlfunc/"pack">.
- Tie/RefHash.pm Base class for tied hashes with references as keys
+=head2 pack() and unpack() support counted strings
- UNIVERSAL.pm Base class for *ALL* classes
+The template character '#' can be used to specify a counted string
+type to be packed or unpacked. See L<perlfunc/"pack">.
-=head2 Fcntl
+=head2 $^X variables may now have names longer than one character
-New constants in the existing Fcntl modules are now supported,
-provided that your operating system happens to support them:
+Formerly, $^X was synonymous with ${"\cX"}, but $^XY was a syntax
+error. Now variable names that begin with a control character may be
+arbitrarily long. However, for compatibility reasons, these variables
+I<must> be written with explicit braces, as C<${^XY}> for example.
+C<${^XYZ}> is synonymous with ${"\cXYZ"}. Variable names with more
+than one control character, such as C<${^XY^Z}>, are illegal.
- F_GETOWN F_SETOWN
- O_ASYNC O_DEFER O_DSYNC O_FSYNC O_SYNC
- O_EXLOCK O_SHLOCK
+The old syntax has not changed. As before, `^X' may be either a
+literal control-X character or the two-character sequence `caret' plus
+`X'. When braces are omitted, the variable name stops after the
+control character. Thus C<"$^XYZ"> continues to be synonymous with
+C<$^X . "YZ"> as before.
-These constants are intended for use with the Perl operators sysopen()
-and fcntl() 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 fcntl() and open().
+As before, lexical variables may not have names beginning with control
+characters. As before, variables whose names begin with a control
+character are always forced to be in package `main'. All such variables
+are reserved for future extensions, except those that begin with
+C<^_>, which may be used by user programs and is guaranteed not to
+acquire special meaning in any future version of Perl.
-In addition, the Fcntl module now provides these constants for use
-with the Perl operator flock():
+=head1 Significant bug fixes
- LOCK_SH LOCK_EX LOCK_NB LOCK_UN
+=head2 E<lt>HANDLEE<gt> on empty files
-These constants are defined in all environments (because where there is
-no flock() system call, Perl emulates it). However, for historical
-reasons, these constants are not exported unless they are explicitly
-requested with the ":flock" tag (e.g. C<use Fcntl ':flock'>).
+With C<$/> set to C<undef>, slurping an empty file returns a string of
+zero length (instead of C<undef>, as it used to) the first time the
+HANDLE is read. Further reads yield C<undef>.
-=head2 IO
+This means that the following will append "foo" to an empty file (it used
+to do nothing):
-The IO module provides a simple mechanism to load all of the IO modules at one
-go. Currently this includes:
+ perl -0777 -pi -e 's/^/foo/' empty_file
- IO::Handle
- IO::Seekable
- IO::File
- IO::Pipe
- IO::Socket
+The behaviour of:
-For more information on any of these modules, please see its
-respective documentation.
+ perl -pi -e 's/^/foo/' empty_file
-=head2 Math::Complex
+is unchanged (it continues to leave the file empty).
-The Math::Complex module has been totally rewritten, and now supports
-more operations. These are overloaded:
+=head2 C<eval '...'> improvements
- + - * / ** <=> neg ~ abs sqrt exp log sin cos atan2 "" (stringify)
+Line numbers (as reflected by caller() and most diagnostics) within
+C<eval '...'> were often incorrect when here documents were involved.
+This has been corrected.
-And these functions are now exported:
+Lexical lookups for variables appearing in C<eval '...'> within
+functions that were themselves called within an C<eval '...'> were
+searching the wrong place for lexicals. The lexical search now
+correctly ends at the subroutine's block boundary.
- 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
+Parsing of here documents used to be flawed when they appeared as
+the replacement expression in C<eval 's/.../.../e'>. This has
+been fixed.
-=head2 Math::Trig
+=head2 Automatic flushing of output buffers
-This new module provides a simpler interface to parts of Math::Complex for
-those who need trigonometric functions only for real numbers.
+fork(), exec(), system(), qx//, and pipe open()s now flush buffers
+of all files opened for output when the operation
+was attempted. This mostly eliminates confusing
+buffering mishaps suffered by users unaware of how Perl internally
+handles I/O.
-=head2 DB_File
+=head2 Better diagnostics on meaningless filehandle operations
-There have been quite a few changes made to DB_File. Here are a few of
-the highlights:
+Constructs such as C<open(E<lt>FHE<gt>)> and C<close(E<lt>FHE<gt>)>
+are compile time errors. Attempting to read from filehandles that
+were opened only for writing will now produce warnings (just as
+writing to read-only filehandles does).
-=over
+=head1 Supported Platforms
-=item *
-
-Fixed a handful of bugs.
+=over 4
=item *
-By public demand, added support for the standard hash function exists().
+VM/ESA is now supported.
=item *
-Made it compatible with Berkeley DB 1.86.
+Siemens BS2000 is now supported under the POSIX Shell.
=item *
-Made negative subscripts work with RECNO interface.
+The Mach CThreads (NEXTSTEP, OPENSTEP) are now supported by the Thread
+extension.
=item *
-Changed the default flags from O_RDWR to O_CREAT|O_RDWR and the default
-mode from 0640 to 0666.
+GNU/Hurd is now supported.
=item *
-Made DB_File automatically import the open() constants (O_RDWR,
-O_CREAT etc.) from Fcntl, if available.
+Rhapsody is now supported.
=item *
-Updated documentation.
-
-=back
-
-Refer to the HISTORY section in DB_File.pm for a complete list of
-changes. Everything after DB_File 1.01 has been added since 5.003.
-
-=head2 Net::Ping
-
-Major rewrite - support added for both udp echo and real icmp pings.
-
-=head2 Object-oriented overrides for builtin operators
-
-Many of the Perl builtins returning lists now have
-object-oriented overrides. These are:
-
- File::stat
- Net::hostent
- Net::netent
- Net::protoent
- Net::servent
- Time::gmtime
- Time::localtime
- User::grent
- User::pwent
-
-For example, you can now say
-
- use File::stat;
- use User::pwent;
- $his = (stat($filename)->st_uid == pwent($whoever)->pw_uid);
-
-=head1 Utility Changes
-
-=head2 pod2html
-
-=over
-
-=item Sends converted HTML to standard output
-
-The I<pod2html> utility included with Perl 5.004 is entirely new.
-By default, it sends the converted HTML to its standard output,
-instead of writing it to a file like Perl 5.003's I<pod2html> did.
-Use the B<--outfile=FILENAME> option to write to a file.
-
-=back
-
-=head2 xsubpp
-
-=over
-
-=item C<void> XSUBs now default to returning nothing
-
-Due to a documentation/implementation bug in previous versions of
-Perl, XSUBs with a return type of C<void> have actually been
-returning one value. Usually that value was the GV for the XSUB,
-but sometimes it was some already freed or reused value, which would
-sometimes lead to program failure.
-
-In Perl 5.004, if an XSUB is declared as returning C<void>, it
-actually returns no value, i.e. an empty list (though there is a
-backward-compatibility exception; see below). If your XSUB really
-does return an SV, you should give it a return type of C<SV *>.
-
-For backward compatibility, I<xsubpp> tries to guess whether a
-C<void> XSUB is really C<void> or if it wants to return an C<SV *>.
-It does so by examining the text of the XSUB: if I<xsubpp> finds
-what looks like an assignment to C<ST(0)>, it assumes that the
-XSUB's return type is really C<SV *>.
+EPOC is is now supported (on Psion 5).
=back
-=head1 C Language API Changes
-
-=over
-
-=item C<gv_fetchmethod> and C<perl_call_sv>
-
-The C<gv_fetchmethod> function finds a method for an object, just like
-in Perl 5.003. The GV 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 C<perl_call_sv>.
-Instead, you should use the C<GvCV> macro on the GV to extract its CV,
-and pass the CV to C<perl_call_sv>.
-
-The most likely symptom of passing the result of C<gv_fetchmethod> to
-C<perl_call_sv> is Perl's producing an "Undefined subroutine called"
-error on the I<second> call to a given method (since there is no cache
-on the first call).
+=head1 New tests
-=item C<perl_eval_pv>
+=over 4
-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
-L<perlguts>, L<perlembed> and L<perlcall> for details and examples.
-
-=item Extended API for manipulating hashes
-
-Internal handling of hash keys has changed. The old hashtable API is
-still fully supported, and will likely remain so. The additions to the
-API allow passing keys as C<SV*>s, so that C<tied> 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 C<SV*> keys. These
-additions also make it feasible to manipulate C<HE*>s (hash entries),
-which can be more efficient. See L<perlguts> for details.
-
-=back
-
-=head1 Documentation Changes
-
-Many of the base and library pods were updated. These
-new pods are included in section 1:
-
-=over
+=item op/io_const
-=item L<perldelta>
+IO constants (SEEK_*, _IO*).
-This document.
+=item op/io_dir
-=item L<perlfaq>
+Directory-related IO methods (new, read, close, rewind, tied delete).
-Frequently asked questions.
+=item op/io_multihomed
-=item L<perllocale>
+INET sockets with multi-homed hosts.
-Locale support (internationalization and localization).
+=item op/io_poll
-=item L<perltoot>
+IO poll().
-Tutorial on Perl OO programming.
+=item op/io_unix
-=item L<perlapio>
+UNIX sockets.
-Perl internal IO abstraction interface.
+=item op/filetest
-=item L<perlmodlib>
+File test operators.
-Perl module library and recommended practice for module creation.
-Extracted from L<perlmod> (which is much smaller as a result).
+=item op/lex_assign
-=item L<perldebug>
-
-Although not new, this has been massively updated.
-
-=item L<perlsec>
-
-Although not new, this has been massively updated.
+Verify operations that access pad objects (lexicals and temporaries).
=back
-=head1 New Diagnostics
-
-Several new conditions will trigger warnings that were
-silent before. Some only affect certain platforms.
-The following new warnings and errors outline these.
-These messages are classified as follows (listed in
-increasing order of desperation):
-
- (W) A warning (optional).
- (D) A deprecation (optional).
- (S) A severe warning (mandatory).
- (F) A fatal error (trappable).
- (P) An internal error you should never see (trappable).
- (X) A very fatal error (nontrappable).
- (A) An alien error message (not generated by Perl).
-
-=over
-
-=item "my" variable %s masks earlier declaration in same scope
-
-(S) A lexical variable has been redeclared in the same scope, effectively
-eliminating all access to the previous instance. This is almost always
-a typographical error. Note that the earlier variable will still exist
-until the end of the scope or until all closure referents to it are
-destroyed.
-
-=item %s argument is not a HASH element or slice
-
-(F) The argument to delete() must be either a hash element, such as
-
- $foo{$bar}
- $ref->[12]->{"susie"}
-
-or a hash slice, such as
-
- @foo{$bar, $baz, $xyzzy}
- @{$ref->[12]}{"susie", "queue"}
-
-=item Allocation too large: %lx
-
-(X) You can't allocate more than 64K on an MS-DOS machine.
-
-=item Allocation too large
+=head1 Modules and Pragmata
-(F) You can't allocate more than 2^31+"small amount" bytes.
+=head2 Modules
-=item Applying %s to %s will act on scalar(%s)
+=over 4
-(W) The pattern match (//), substitution (s///), and translation (tr///)
-operators work on scalar values. If you apply one of them to an array
-or a hash, it will convert the array or hash to a scalar value -- the
-length of an array, or the population info of a hash -- and then work on
-that scalar value. This is probably not what you meant to do. See
-L<perlfunc/grep> and L<perlfunc/map> for alternatives.
+=item ByteLoader
-=item Attempt to free nonexistent shared string
+The ByteLoader is a dedication extension to generate and run
+Perl bytecode. See L<ByteLoader>.
-(P) Perl maintains a reference counted internal table of strings to
-optimize the storage and access of hash keys and other strings. This
-indicates someone tried to decrement the reference count of a string
-that can no longer be found in the table.
+=item B
-=item Attempt to use reference as lvalue in substr
+The Perl Compiler suite has been extensively reworked for this
+release.
-(W) You supplied a reference as the first argument to substr() used
-as an lvalue, which is pretty strange. Perhaps you forgot to
-dereference it first. See L<perlfunc/substr>.
+=item Devel::DProf
-=item Can't redefine active sort subroutine %s
+Devel::DProf, a Perl source code profiler has been added.
-(F) Perl optimizes the internal handling of sort subroutines and keeps
-pointers into them. You tried to redefine one such sort subroutine when it
-was currently active, which is not allowed. If you really want to do
-this, you should write C<sort { &func } @x> instead of C<sort func @x>.
+=item Dumpvalue
-=item Can't use bareword ("%s") as %s ref while "strict refs" in use
+Added Dumpvalue module provides screen dumps of Perl data.
-(F) Only hard references are allowed by "strict refs". Symbolic references
-are disallowed. See L<perlref>.
+=item Benchmark
-=item Cannot resolve method `%s' overloading `%s' in package `%s'
+You can now run tests for I<n> seconds instead of guessing the right
+number of tests to run: e.g. timethese(-5, ...) will run each
+code for at least 5 CPU seconds. Zero as the "number of repetitions"
+means "for at least 3 CPU seconds". The output format has also
+changed. For example:
-(P) Internal error trying to resolve overloading specified by a method
-name (as opposed to a subroutine reference).
+use Benchmark;$x=3;timethese(-5,{a=>sub{$x*$x},b=>sub{$x**2}})
-=item Constant subroutine %s redefined
+will now output something like this:
-(S) You redefined a subroutine which had previously been eligible for
-inlining. See L<perlsub/"Constant Functions"> for commentary and
-workarounds.
+Benchmark: running a, b, each for at least 5 CPU seconds...
+ a: 5 wallclock secs ( 5.77 usr + 0.00 sys = 5.77 CPU) @ 200551.91/s (n=1156516)
+ b: 4 wallclock secs ( 5.00 usr + 0.02 sys = 5.02 CPU) @ 159605.18/s (n=800686)
-=item Constant subroutine %s undefined
+New features: "each for at least N CPU seconds...", "wallclock secs",
+and the "@ operations/CPU second (n=operations)".
-(S) You undefined a subroutine which had previously been eligible for
-inlining. See L<perlsub/"Constant Functions"> for commentary and
-workarounds.
+=item Devel::Peek
-=item Copy method did not return a reference
+The Devel::Peek module provides access to the internal representation
+of Perl variables and data. It is a data debugging tool for the XS programmer.
-(F) The method which overloads "=" is buggy. See L<overload/Copy Constructor>.
+=item Fcntl
-=item Died
+More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for
+large (more than 4G) file access (64-bit support is not yet
+working, though, so no need to get overly excited), Free/Net/OpenBSD
+locking behaviour flags F_FLOCK, F_POSIX, Linux F_SHLCK, and
+O_ACCMODE: the mask of O_RDONLY, O_WRONLY, and O_RDWR.
-(F) You passed die() an empty string (the equivalent of C<die "">) or
-you called it with no args and both C<$@> and C<$_> were empty.
+=item File::Spec
-=item Exiting pseudo-block via %s
+New methods have been added to the File::Spec module: devnull() returns
+the name of the null device (/dev/null on Unix) and tmpdir() the name of
+the temp directory (normally /tmp on Unix). There are now also methods
+to convert between absolute and relative filenames: abs2rel() and
+rel2abs(). For compatibility with operating systems that specify volume
+names in file paths, the splitpath(), splitdir(), and catdir() methods
+have been added.
-(W) You are exiting a rather special block construct (like a sort block or
-subroutine) by unconventional means, such as a goto, or a loop control
-statement. See L<perlfunc/sort>.
+=item File::Spec::Functions
-=item Identifier too long
+The new File::Spec::Functions modules provides a function interface
+to the File::Spec module. Allows shorthand
-(F) Perl limits identifiers (names for variables, functions, etc.) to
-252 characters for simple names, somewhat more for compound names (like
-C<$A::B>). You've exceeded Perl's limits. Future versions of Perl are
-likely to eliminate these arbitrary limitations.
+ $fullname = catfile($dir1, $dir2, $file);
-=item Illegal character %s (carriage return)
+instead of
-(F) A carriage return character was found in the input. This is an
-error, and not a warning, because carriage return characters can break
-multi-line strings, including here documents (e.g., C<print E<lt>E<lt>EOF;>).
+ $fullname = File::Spec->catfile($dir1, $dir2, $file);
-=item Illegal switch in PERL5OPT: %s
+=item Math::BigInt
-(X) The PERL5OPT environment variable may only be used to set the
-following switches: B<-[DIMUdmw]>.
+The logical operations C<E<lt>E<lt>>, C<E<gt>E<gt>>, C<&>, C<|>,
+and C<~> are now supported on bigints.
-=item Integer overflow in hex number
+=item Math::Complex
-(S) The literal hex number you have specified is too big for your
-architecture. On a 32-bit architecture the largest hex literal is
-0xFFFFFFFF.
+The accessor methods Re, Im, arg, abs, rho, and theta can now also
+act as mutators (accessor $z->Re(), mutator $z->Re(3)).
-=item Integer overflow in octal number
+=item Math::Trig
-(S) The literal octal number you have specified is too big for your
-architecture. On a 32-bit architecture the largest octal literal is
-037777777777.
+A little bit of radial trigonometry (cylindrical and spherical),
+radial coordinate conversions, and the great circle distance were added.
-=item internal error: glob failed
+=item SDBM_File
-(P) Something went wrong with the external program(s) used for C<glob>
-and C<E<lt>*.cE<gt>>. This may mean that your csh (C shell) is
-broken. If so, you should change all of the csh-related variables in
-config.sh: If you have tcsh, make the variables refer to it as if it
-were csh (e.g. C<full_csh='/usr/bin/tcsh'>); otherwise, make them all
-empty (except that C<d_csh> should be C<'undef'>) so that Perl will
-think csh is missing. In either case, after editing config.sh, run
-C<./Configure -S> and rebuild Perl.
+An EXISTS method has been added to this module (and sdbm_exists() has
+been added to the underlying sdbm library), so one can now call exists
+on an SDBM_File tied hash and get the correct result, rather than a
+runtime error.
-=item Invalid conversion in %s: "%s"
+=item Time::Local
-(W) Perl does not understand the given format conversion.
-See L<perlfunc/sprintf>.
+The timelocal() and timegm() functions used to silently return bogus
+results when the date exceeded the machine's integer range. They
+now consistently croak() if the date falls in an unsupported range.
-=item Invalid type in pack: '%s'
+=item Win32
-(F) The given character is not a valid pack type. See L<perlfunc/pack>.
+The error return value in list context has been changed for all functions
+that return a list of values. Previously these functions returned a list
+with a single element C<undef> if an error occurred. Now these functions
+return the empty list in these situations. This applies to the following
+functions:
-=item Invalid type in unpack: '%s'
+ Win32::FsType
+ Win32::GetOSVersion
-(F) The given character is not a valid unpack type. See L<perlfunc/unpack>.
+The remaining functions are unchanged and continue to return C<undef> on
+error even in list context.
-=item Name "%s::%s" used only once: possible typo
+The Win32::SetLastError(ERROR) function has been added as a complement
+to the Win32::GetLastError() function.
-(W) Typographical errors often show up as unique variable names.
-If you had a good reason for having a unique name, then just mention
-it again somehow to suppress the message (the C<use vars> pragma is
-provided for just this purpose).
+The new Win32::GetFullPathName(FILENAME) returns the full absolute
+pathname for FILENAME in scalar context. In list context it returns
+a two-element list containing the fully qualified directory name and
+the filename.
-=item Null picture in formline
+=item DBM Filters
-(F) The first argument to formline must be a valid format picture
-specification. It was found to be empty, which probably means you
-supplied it an uninitialized value. See L<perlform>.
+A new feature called "DBM Filters" has been added to all the
+DBM modules--DB_File, GDBM_File, NDBM_File, ODBM_File, and SDBM_File.
+DBM Filters add four new methods to each DBM module:
-=item Offset outside string
+ filter_store_key
+ filter_store_value
+ filter_fetch_key
+ filter_fetch_value
-(F) You tried to do a read/write/send/recv operation with an offset
-pointing outside the buffer. This is difficult to imagine.
-The sole exception to this is that C<sysread()>ing past the buffer
-will extend the buffer and zero pad the new area.
+These can be used to filter key-value pairs before the pairs are
+written to the database or just after they are read from the database.
+See L<perldbmfilter> for further information.
-=item Out of memory!
-
-(X|F) The malloc() function returned 0, indicating there was insufficient
-remaining memory (or virtual memory) to satisfy the request.
-
-The request was judged to be small, so the possibility to trap it
-depends on the way Perl was compiled. By default it is not trappable.
-However, if compiled for this, Perl may use the contents of C<$^M> as
-an emergency pool after die()ing with this message. In this case the
-error is trappable I<once>.
-
-=item Out of memory during request for %s
-
-(F) The malloc() function returned 0, indicating there was insufficient
-remaining memory (or virtual memory) to satisfy the request. However,
-the request was judged large enough (compile-time default is 64K), so
-a possibility to shut down by trapping this error is granted.
-
-=item panic: frexp
-
-(P) The library function frexp() failed, making printf("%f") impossible.
-
-=item Possible attempt to put comments in qw() list
-
-(W) qw() lists contain items separated by whitespace; as with literal
-strings, comment characters are not ignored, but are instead treated
-as literal data. (You may have used different delimiters than the
-exclamation marks parentheses shown here; braces are also frequently
-used.)
-
-You probably wrote something like this:
-
- @list = qw(
- a # a comment
- b # another comment
- );
-
-when you should have written this:
-
- @list = qw(
- a
- b
- );
-
-If you really want comments, build your list the
-old-fashioned way, with quotes and commas:
-
- @list = (
- 'a', # a comment
- 'b', # another comment
- );
-
-=item Possible attempt to separate words with commas
-
-(W) qw() lists contain items separated by whitespace; therefore commas
-aren't needed to separate the items. (You may have used different
-delimiters than the parentheses shown here; braces are also frequently
-used.)
-
-You probably wrote something like this:
-
- qw! a, b, c !;
-
-which puts literal commas into some of the list items. Write it without
-commas if you don't want them to appear in your data:
-
- qw! a b c !;
-
-=item Scalar value @%s{%s} better written as $%s{%s}
-
-(W) You've used a hash slice (indicated by @) to select a single element of
-a hash. Generally it's better to ask for a scalar value (indicated by $).
-The difference is that C<$foo{&bar}> always behaves like a scalar, both when
-assigning to it and when evaluating its argument, while C<@foo{&bar}> behaves
-like a list when you assign to it, and provides a list context to its
-subscript, which can do weird things if you're expecting only one subscript.
-
-=item Stub found while resolving method `%s' overloading `%s' in package `%s'
-
-(P) Overloading resolution over @ISA tree may be broken by importing stubs.
-Stubs should never be implicitely created, but explicit calls to C<can>
-may break this.
-
-=item Too late for "B<-T>" option
-
-(X) The #! line (or local equivalent) in a Perl script contains the
-B<-T> option, but Perl was not invoked with B<-T> in its argument
-list. This is an error because, by the time Perl discovers a B<-T> in
-a script, it's too late to properly taint everything from the
-environment. So Perl gives up.
-
-=item untie attempted while %d inner references still exist
-
-(W) A copy of the object returned from C<tie> (or C<tied>) was still
-valid when C<untie> was called.
-
-=item Unrecognized character %s
+=back
-(F) The Perl parser has no idea what to do with the specified character
-in your Perl script (or eval). Perhaps you tried to run a compressed
-script, a binary program, or a directory as a Perl program.
+=head2 Pragmata
-=item Unsupported function fork
+C<use utf8> to enable UTF-8 and Unicode support.
-(F) Your version of executable does not support forking.
+C<use caller 'encoding'> allows modules to inherit pragmatic attributes
+from the caller's context. C<encoding> is currently the only supported
+attribute.
-Note that under some systems, like OS/2, there may be different flavors of
-Perl executables, some of which may support fork, some not. Try changing
-the name you call Perl by to C<perl_>, C<perl__>, and so on.
+Lexical warnings pragma, C<use warning;>, to control optional warnings.
-=item Use of "$$<digit>" to mean "${$}<digit>" is deprecated
+C<use filetest> to control the behaviour of filetests (C<-r> C<-w> ...).
+Currently only one subpragma implemented, "use filetest 'access';",
+that enables the use of access(2) or equivalent to check
+permissions instead of using stat(2) as usual. This matters
+in filesystems where there are ACLs (access control lists): the
+stat(2) might lie, but access(2) knows better.
-(D) Perl versions before 5.004 misinterpreted any type marker followed
-by "$" and a digit. For example, "$$0" was incorrectly taken to mean
-"${$}0" instead of "${$0}". This bug is (mostly) fixed in Perl 5.004.
+=head1 Utility Changes
-However, the developers of Perl 5.004 could not fix this bug completely,
-because at least two widely-used modules depend on the old meaning of
-"$$0" in a string. So Perl 5.004 still interprets "$$<digit>" in the
-old (broken) way inside strings; but it generates this message as a
-warning. And in Perl 5.005, this special treatment will cease.
+Todo.
-=item Value of %s can be "0"; test with defined()
+=head1 Documentation Changes
-(W) In a conditional expression, you used <HANDLE>, <*> (glob), C<each()>,
-or C<readdir()> as a boolean value. Each of these constructs can return a
-value of "0"; that would make the conditional expression false, which is
-probably not what you intended. When using these constructs in conditional
-expressions, test their values with the C<defined> operator.
+=over 4
-=item Variable "%s" may be unavailable
+=item perlopentut.pod
-(W) An inner (nested) I<anonymous> subroutine is inside a I<named>
-subroutine, and outside that is another subroutine; and the anonymous
-(innermost) subroutine is referencing a lexical variable defined in
-the outermost subroutine. For example:
+A tutorial on using open() effectively.
- sub outermost { my $a; sub middle { sub { $a } } }
+=item perlreftut.pod
-If the anonymous subroutine is called or referenced (directly or
-indirectly) from the outermost subroutine, it will share the variable
-as you would expect. But if the anonymous subroutine is called or
-referenced when the outermost subroutine is not active, it will see
-the value of the shared variable as it was before and during the
-*first* call to the outermost subroutine, which is probably not what
-you want.
+A tutorial that introduces the essentials of references.
-In these circumstances, it is usually best to make the middle
-subroutine anonymous, using the C<sub {}> syntax. Perl has specific
-support for shared variables in nested anonymous subroutines; a named
-subroutine in between interferes with this feature.
+=item perltootc.pod
-=item Variable "%s" will not stay shared
+A tutorial on managing class data for object modules.
-(W) An inner (nested) I<named> subroutine is referencing a lexical
-variable defined in an outer subroutine.
+=back
-When the inner subroutine is called, it will probably see the value of
-the outer subroutine's variable as it was before and during the
-*first* call to the outer subroutine; in this case, after the first
-call to the outer subroutine is complete, the inner and outer
-subroutines will no longer share a common value for the variable. In
-other words, the variable will no longer be shared.
+=head1 New Diagnostics
-Furthermore, if the outer subroutine is anonymous and references a
-lexical variable outside itself, then the outer and inner subroutines
-will I<never> share the given variable.
+=item /%s/: Unrecognized escape \\%c passed through
-This problem can usually be solved by making the inner subroutine
-anonymous, using the C<sub {}> syntax. When inner anonymous subs that
-reference variables in outer subroutines are called or referenced,
-they are automatically rebound to the current values of such
-variables.
+(W) You used a backslash-character combination which is not recognized
+by Perl. This combination appears in an interpolated variable or a
+C<'>-delimited regular expression.
-=item Warning: something's wrong
+=item Filehandle %s opened only for output
-(W) You passed warn() an empty string (the equivalent of C<warn "">) or
-you called it with no args and C<$_> was empty.
+(W) You tried to read from a filehandle opened only for writing. If you
+intended it to be a read-write filehandle, you needed to open it with
+"+E<lt>" or "+E<gt>" or "+E<gt>E<gt>" instead of with "E<lt>" or nothing. If
+you intended only to read from the file, use "E<lt>". See
+L<perlfunc/open>.
-=item Ill-formed logical name |%s| in prime_env_iter
+=item Missing command in piped open
-(W) A warning peculiar to VMS. A logical name was encountered when preparing
-to iterate over %ENV which violates the syntactic rules governing logical
-names. Since it cannot be translated normally, it is skipped, and will not
-appear in %ENV. This may be a benign occurrence, as some software packages
-might directly modify logical name tables and introduce nonstandard names,
-or it may indicate that a logical name table has been corrupted.
+(W) You used the C<open(FH, "| command")> or C<open(FH, "command |")>
+construction, but the command was missing or blank.
-=item Got an error from DosAllocMem
+=item Unrecognized escape \\%c passed through
-(P) An error peculiar to OS/2. Most probably you're using an obsolete
-version of Perl, and this should not happen anyway.
+(W) You used a backslash-character combination which is not recognized
+by Perl.
-=item Malformed PERLLIB_PREFIX
+=item defined(@array) is deprecated
-(F) An error peculiar to OS/2. PERLLIB_PREFIX should be of the form
+(D) defined() is not usually useful on arrays because it checks for an
+undefined I<scalar> value. If you want to see if the array is empty,
+just use C<if (@array) { # not empty }> for example.
- prefix1;prefix2
+=item defined(%hash) is deprecated
-or
+(D) defined() is not usually useful on hashes because it checks for an
+undefined I<scalar> value. If you want to see if the hash is empty,
+just use C<if (%hash) { # not empty }> for example.
- prefix1 prefix2
+=head1 Obsolete Diagnostics
-with nonempty prefix1 and prefix2. If C<prefix1> is indeed a prefix
-of a builtin library search path, prefix2 is substituted. The error
-may appear if components are not found, or are too long. See
-"PERLLIB_PREFIX" in F<README.os2>.
+Todo.
-=item PERL_SH_DIR too long
+=head1 Configuration Changes
-(F) An error peculiar to OS/2. PERL_SH_DIR is the directory to find the
-C<sh>-shell in. See "PERL_SH_DIR" in F<README.os2>.
+=head2 installusrbinperl
-=item Process terminated by SIG%s
+You can use "Configure -Uinstallusrbinperl" which causes installperl
+to skip installing perl also as /usr/bin/perl. This is useful if you
+prefer not to modify /usr/bin for some reason or another but harmful
+because many scripts assume to find Perl in /usr/bin/perl.
-(W) This is a standard message issued by OS/2 applications, while *nix
-applications die in silence. It is considered a feature of the OS/2
-port. One can easily disable this by appropriate sighandlers, see
-L<perlipc/"Signals">. See also "Process terminated by SIGTERM/SIGINT"
-in F<README.os2>.
+=head2 SOCKS support
-=back
+You can use "Configure -Dusesocks" which causes Perl to probe
+for the SOCKS proxy protocol library, http://www.socks.nec.com/
=head1 BUGS
If you find what you think is a bug, you might check the headers of
-recently posted articles in the comp.lang.perl.misc newsgroup.
+articles recently posted to the comp.lang.perl.misc newsgroup.
There may also be information at http://www.perl.com/perl/, the Perl
Home Page.
If you believe you have an unreported bug, please run the B<perlbug>
-program included with your release. Make sure you trim your bug down
+program included with your release. Make sure to trim your bug down
to a tiny but sufficient test case. Your bug report, along with the
-output of C<perl -V>, will be sent off to <F<perlbug@perl.com>> to be
+output of C<perl -V>, will be sent off to perlbug@perl.com to be
analysed by the Perl porting team.
=head1 SEE ALSO
The F<Changes> file for exhaustive details on what changed.
-The F<INSTALL> file for how to build Perl. This file has been
-significantly updated for 5.004, so even veteran users should
-look through it.
+The F<INSTALL> file for how to build Perl.
The F<README> file for general stuff.
-The F<Copying> file for copyright information.
+The F<Artistic> and F<Copying> files for copyright information.
=head1 HISTORY
-Constructed by Tom Christiansen, grabbing material with permission
-from innumerable contributors, with kibitzing by more than a few Perl
-porters.
+Written by Gurusamy Sarathy <F<gsar@umich.edu>>, with many contributions
+from The Perl Porters.
+
+Send omissions or corrections to <F<perlbug@perl.com>>.
-Last update: Wed May 14 11:14:09 EDT 1997
+=cut
https://perl5.git.perl.org / perl5.git / blobdiff