=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 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
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
Note that you still cannot use my() on global punctuation variables
such as $_ and the like.
-=item unpack() and pack()
+=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
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
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). 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.
+This port has not been as well tested as the "native" port described
+above (which is not as well tested as we'd like either :)
+
+=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:
Module Required Version for Perl 5.004
------ -------------------------------
- Filter 1.12
- LWP 5.08
+ Filter Filter-1.12
+ LWP libwww-perl-5.08
Tk Tk400.202 (-w makes noise)
+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.
+
=head2 Installation directories
The I<installperl> script now places the Perl source files for
Brand new modules, arranged by topic rather than strictly
alphabetically:
- CPAN interface to Comprehensive Perl Archive Network
- CPAN::FirstTime create a CPAN configuration file
- CPAN::Nox run CPAN while avoiding compiled extensions
+ 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
+
+ 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
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
error on the I<second> call to a given method (since there is no cache
on the first call).
+=item C<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
+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
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
(W) Typographical errors often show up as unique variable names.
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
qw! a b c !;
-=item Recursive substitution detected
-
-(F) The replacement string of a substitution caused the recursive
-execution of that very same substituion. Perl cannot keep track of
-special variables (C<$1>, etc.) under such circumstances.
-
=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
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