=head1 Supported Environments
-Perl5.004 builds out of the box on Unix, Plan9, LynxOS, VMS, OS/2,
-QNX, and AmigaOS.
+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 Core Changes
-Most importantly, many bugs were fixed. See the F<Changes>
-file in the distribution for details.
+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
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>, and C<-m>, and B<-T> options
+=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
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->bar()> or C<$obj->bar()>).
+(e.g. C<Foo-E<gt>bar()> or C<$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
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
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, 5.001, and 5.002 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.
+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:
as a blessing, since that indicates a potentially-serious security
hole was just plugged.
+The new restrictions when tainting include:
+
+=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.
+
+=item No spawning if tainted $TERM doesn't look like a terminal name
+
+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).
+
+=back
+
=head2 New Opcode module and revised Safe module
A new Opcode module supports the creation, manipulation and
IO::Handle, IO::Seekable, and IO::File. We suggest, but do not
require, that you use the IO::* modules in new code.
-In harmony with this change, C<*GLOB{FILEHANDLE}> is now a
-backward-compatible synonym for C<*STDOUT{IO}>.
+In harmony with this change, C<*GLOB{FILEHANDLE}> is now just a
+backward-compatible synonym for C<*GLOB{IO}>.
=head2 Internal change: PerlIO abstraction interface
instead of stdio. See L<perlapio> for more details, and
the F<INSTALL> file for how to use it.
+=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)>>.
+
+=back
+
+=head2 New and changed builtin constants
+
+=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 printf and sprintf
-now support "%i" as a synonym for "%d", and the "h" modifier.
-So "%hi" means "short integer in decimal", and "%ho" means
-"unsigned short integer as octal".
+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
first. Bit eight of each byte is set, except for the last byte, in
which bit eight is clear.
-Previous to Perl 5.004, both pack() and unpack() would ignore any
-unknown type characters in the template string. Now a fatal error will
-be generated.
+Both pack() and unpack() now fail when their templates contain invalid
+types. (Invalid types used to be ignored.)
-=item sysseek() and systell()
+=item sysseek()
-These are new. The sysseek() operator is a variant of seek() that works
-on the system file pointer. It is the only reliable way to seek before
-using sysread() or syswrite(). Its companion operator systell() reports
-the current position of the system file pointer.
+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
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//g> does not reset search position on failure
-
-The C<m//g> match iteration construct used to reset its target string's
-search position (which is visible through the C<pos> operator) when a
-match failed; as a result, the next C<m//g> match would start at the
-beginning of the string). With Perl 5.004, the search position must be
-reset explicitly, as with C<pos $str = 0;>, or by modifying the target
-string. This change in Perl makes it possible to chain matches together
-in conjunction with the C<\G> zero-width assertion. See L<perlop> and
-L<perlre>.
+=item C<m//gc> does not reset search position on failure
-Here is an illustration of what it takes to get the old behavior:
-
- for ( qw(this and that are not what you think you got) ) {
- while ( /(\w*t\w*)/g ) { print "t word is: $1\n" }
- pos = 0; # REQUIRED FOR 5.004
- while ( /(\w*a\w*)/g ) { print "a word is: $1\n" }
- print "\n";
- }
+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 ?*+{}
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, and is fine now:
+before (printed only zeros), but is fine now:
my $i;
foreach $i ( 1 .. 10 ) {
- format =
+ write;
+ }
+ format =
my i is @#
$i
.
- write;
- }
=back
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>
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:
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's built-in stat
- Net/hostent.pm By-name interface to Perl's built-in gethost*
- Net/netent.pm By-name interface to Perl's built-in getnet*
- Net/protoent.pm By-name interface to Perl's built-in getproto*
- Net/servent.pm By-name interface to Perl's built-in getserv*
- Time/gmtime.pm By-name interface to Perl's built-in gmtime
- Time/localtime.pm By-name interface to Perl's built-in localtime
+ 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 built-in getgr*
- User/pwent.pm By-name interface to Perl's built-in getpw*
+ User/grent.pm By-name interface to Perl's builtin getgr*
+ User/pwent.pm By-name interface to Perl's builtin getpw*
Tie/RefHash.pm Base class for tied hashes with references as keys
=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<perl_eval_pv>
-A new function handy for eval'ing strings of Perl code inside C code.
+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.
This document.
+=item L<perlfaq>
+
+Frequently asked questions.
+
=item L<perllocale>
Locale support (internationalization and localization).
Perl internal IO abstraction interface.
+=item L<perlmodlib>
+
+Perl module library and recommended practice for module creation.
+Extracted from L<perlmod> (which is much smaller as a result).
+
=item L<perldebug>
Although not new, this has been massively updated.
as an lvalue, which is pretty strange. Perhaps you forgot to
dereference it first. See L<perlfunc/substr>.
+=item Can't redefine active sort subroutine %s
+
+(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 Can't use bareword ("%s") as %s ref while "strict refs" in use
(F) Only hard references are allowed by "strict refs". Symbolic references
subroutine) by unconventional means, such as a goto, or a loop control
statement. See L<perlfunc/sort>.
+=item Identifier too long
+
+(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.
+
=item Illegal character %s (carriage return)
(F) A carriage return character was found in the input. This is an
think csh is missing. In either case, after editing config.sh, run
C<./Configure -S> and rebuild Perl.
+=item Invalid conversion in %s: "%s"
+
+(W) Perl does not understand the given format conversion.
+See L<perlfunc/sprintf>.
+
=item Invalid type in pack: '%s'
-
+
(F) The given character is not a valid pack type. See L<perlfunc/pack>.
-
+
=item Invalid type in unpack: '%s'
-
+
(F) The given character is not a valid unpack type. See L<perlfunc/unpack>.
=item Name "%s::%s" used only once: possible typo
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
from innumerable contributors, with kibitzing by more than a few Perl
porters.
-Last update: Sat Mar 8 19:51:26 EST 1997
+Last update: Wed May 14 11:14:09 EDT 1997
https://perl5.git.perl.org / perl5.git / blobdiff