=encoding utf8
+ XXX: This is here for my own reference while editing! -- rjbs, 2012-02-20
+
+ =head1 Notice
+ =head1 Core Enhancements
+ =head1 Security
+ =head1 Incompatible Changes
+ =head1 Deprecations
+ =head1 Performance Enhancements
+ =head1 Modules and Pragmata
+ =head2 New Modules and Pragmata
+ =head2 Updated Modules and Pragmata
+ =head2 Removed Modules and Pragmata
+ =head1 Documentation
+ =head2 New Documentation
+ =head2 Changes to Existing Documentation
+ =head1 Diagnostics
+ =head2 New Diagnostics
+ =head3 New Errors
+ =head3 New Warnings
+ =head2 Changes to Existing Diagnostics
+ =head1 Utility Changes
+ =head1 Configuration and Compilation
+ =head1 Testing
+ =head1 Platform Support
+ =head2 New Platforms
+ =head2 Discontinued Platforms
+ =head2 Platform-Specific Notes
+ =head1 Internal Changes
+ =head1 Selected Bug Fixes
+ =head1 Known Problems
+ =head1 Obituary
+ =head1 Acknowledgements
+ =head1 Reporting Bugs
+ =head1 SEE ALSO
+
=head1 NAME
perl5160delta - what is new for perl v5.16.0
=head1 Core Enhancements
-=head2 C<use charnames> no longer needed for C<\N{I<name>}>
-
-The C<charnames> module is now automatically loaded when needed as if
-the C<:full> and C<:short> options had been specified. See
-L<charnames>.
-
-=head2 Improved performance for Unicode properties in regular expressions
-
-Matching a code point against a Unicode property is now done via a
-binary search instead of linear. This means for example that the worst
-case for a 1000 item property is 10 probes instead of 1000. This
-inefficiency has been compensated for in the past by permanently storing
-in a hash the results of a given probe plus the results for the adjacent
-64 code points, under the theory that near-by code points are likely to
-be searched for. A separate hash was used for each mention of a Unicode
-property in each regular expression. Thus, C<qr/\p{foo}abc\p{foo}/>
-would generate two hashes. Any probes in one instance would be unknown
-to the other, and the hashes could expand separately to be quite large
-if the regular expression were used on many different widely-separated
-code points. This can lead to running out of memory in extreme cases.
-Now, however, there is just one hash shared by all instances of a given
-property. This means that if C<\p{foo}> is matched against "A" in one
-regular expression in a thread, the result will be known immediately to
-all regular expressions, and the relentless march of using up memory is
-slowed considerably.
-
-=head2 C<is_utf8_char()>
-
-The XS-callable function C<is_utf8_char()>, when presented with
-malformed UTF-8 input, can read up to 12 bytes beyond the end of the
-string. This cannot be fixed without changing its API. It is not
-called from CPAN. The documentation now describes how to use it
-safely.
-
-=head2 Other C<is_utf8_foo()> functions, as well as C<utf8_to_foo()>, etc.
-
-Most of the other XS-callable functions that take UTF-8 encoded input
-implicitly assume that the UTF-8 is valid (not malformed) in regards to
-buffer length. Do not do things such as change a character's case or
-see if it is alphanumeric without first being sure that it is valid
-UTF-8. This can be safely done for a whole string by using one of the
-functions C<is_utf8_string()>, C<is_utf8_string_loc()>, and
-C<is_utf8_string_loclen()>.
-
=head2 C<use I<VERSION>>
As of this release, version declarations like C<use v5.16> now disable
the following holds true:
use 5.016;
- # 5.16 features enabled here
+ # only 5.16 features enabled here
use 5.014;
- # 5.16 features disabled here
+ # only 5.14 features enabled here (not 5.16)
C<use v5.12> and higher continue to enable strict, but explicit C<use
strict> and C<no strict> now override the version declaration, even
feature set and can be turned on or off explicitly with C<use feature
'array_base'>.
-=head2 C<UNIVERSAL::VERSION>
+=head2 C<__SUB__>
+
+The new C<__SUB__> token, available under the C<current_sub> feature
+(see L<feature>) or C<use v5.15>, returns a reference to the current
+subroutine, making it easier to write recursive closures.
+
+=head2 New and Improved Built-ins
-The change to C<UNIVERSAL::VERSION> in 5.15.2 has been reverted. It
-now returns a stringified version object once more.
+=head3 Return value of C<eval>
-=head2 C<substr> lvalue revamp
+C<eval> returns C<undef> in scalar context or an empty list in list
+context when there is a run-time error. When C<eval> was passed a
+string in list context and a syntax error occurred, it used to return a
+list containing a single undefined element. Now it returns an empty
+list in list context for all errors [perl #80630].
+
+=head3 More consistent C<eval>
+
+The C<eval> operator sometimes treats a string argument as a sequence of
+characters and sometimes as a sequence of bytes, depending on the
+internal encoding. The internal encoding is not supposed to make any
+difference, but there is code that relies on this inconsistency.
+
+The new C<unicode_eval> and C<evalbytes> features (enabled under C<use
+5.16.0> resolve this. The C<unicode_eval> feature causes C<eval
+$string> to treat the string always as Unicode. The C<evalbytes>
+features provides a function, itself called C<evalbytes>, which
+evaluates its argument always as a string of bytes.
+
+These features also fix oddities with source filters leaking to outer
+dynamic scopes.
+
+See L<feature> for more detail.
+
+=head3 C<substr> lvalue revamp
+
+=for comment Can this be compacted some? -- rjbs, 2012-02-20
When C<substr> is called in lvalue or potential lvalue context with two
or three arguments, a special lvalue scalar is returned that modifies
and the behaviour of negative offsets was never specified, so the
change was deemed acceptable.
-=head2 Return value of C<eval>
-
-C<eval> returns C<undef> in scalar context or an empty list in list
-context when there is a run-time error. When C<eval> was passed a
-string in list context and a syntax error occurred, it used to return a
-list containing a single undefined element. Now it returns an empty
-list in list context for all errors [perl #80630].
-
-=head2 Anonymous handles
-
-Automatically generated file handles are now named __ANONIO__ when the
-variable name cannot be determined, rather than $__ANONIO__.
-
-=head2 Last-accessed filehandle
-
-Perl has an internal variable that stores the last filehandle to be
-accessed. It is used by C<$.> and by C<tell> and C<eof> without
-arguments.
-
-It used to be possible to set this internal variable to a glob copy and
-then modify that glob copy to be something other than a glob, and still
-have the last-accessed filehandle associated with the variable after
-assigning a glob to it again:
-
- my $foo = *STDOUT; # $foo is a glob copy
- <$foo>; # $foo is now the last-accessed handle
- $foo = 3; # no longer a glob
- $foo = *STDERR; # still the last-accessed handle
-
-Now the C<$foo = 3> assignment unsets that internal variable, so there
-is no last-accessed filehandle, just as if C<< <$foo> >> had never
-happened.
-
-=head2 C<__SUB__>
-
-The new C<__SUB__> token, available under the "current_sub" feature
-(see L<feature>) or C<use v5.15>, returns a reference to the current
-subroutine, making it easier to write recursive closures.
-
-=head2 New option for the debugger's B<t> command
-
-The B<t> command in the debugger, which toggles tracing mode, now
-accepts a numeric argument that determines how many levels of
-subroutine calls to trace.
-
-=head2 Return value of C<tied>
+=head3 Return value of C<tied>
The value returned by C<tied> on a tied variable is now the actual
scalar that holds the object to which the variable is tied. This
allows ties to be weakened with C<Scalar::Util::weaken(tied
$tied_variable)>.
+=head2 Unicode Support
-=head2 More consistent C<eval>
+=head3 C<use charnames> is no longer needed for C<\N{I<name>}>
-The C<eval> operator sometimes treats a string argument as a sequence of
-characters and sometimes as a sequence of bytes, depending on the internal
-encoding. The internal encoding is not supposed to make any difference,
-but there is code that relies on this inconsistency.
+When C<\N{I<name>}> is encountered, the C<charnames> module is now
+automatically loaded when needed as if the C<:full> and C<:short>
+options had been specified. See L<charnames> for more information.
-Under C<use v5.15> and higher, the C<unicode_eval> and C<evalbytes>
-features resolve this. The C<unicode_eval> feature causes C<eval $string>
-to treat the string always as Unicode. The C<evalbytes> features provides
-a function, itself called C<evalbytes>, which evaluates its argument always
-as a string of bytes.
-
-These features also fix oddities with source filters leaking to outer
-dynamic scopes.
-
-See L<feature> for more detail.
-
-=head2 $^X converted to an absolute path on FreeBSD, OS X and Solaris
-
-C<$^X> is now converted to an absolute path on OS X, FreeBSD (without
-needing F</proc> mounted) and Solaris 10 and 11. This augments the
-previous approach of using F</proc> on Linux, FreeBSD and NetBSD
-(in all cases, where mounted).
-
-This makes relocatable perl installations more useful on these platforms.
-(See "Relocatable @INC" in F<INSTALL>)
-
-=head2 Unicode Symbol Names
+=head3 Unicode Symbol Names
Perl now has proper support for Unicode in symbol names. It used to be
that C<*{$foo}> would ignore the internal UTF8 flag and use the bytes of
Attributes
-=item *
+=item *
+
+Various warnings and error messages that mention variable names or values,
+methods, etc.
+
+=back
+
+In addition, a parsing bug has been fixed that prevented C<*{é}> from
+implicitly quoting the name, but instead interpreted it as C<*{+é}>, which
+would cause a strict violation.
+
+C<*{"*a::b"}> automatically strips off the * if it is followed by an ASCII
+letter. That has been extended to all Unicode identifier characters.
+
+C<$é> is now subject to "Used only once" warnings. It used to be exempt,
+as it was treated as a punctuation variable.
+
+Also, single-character Unicode punctuation variables (like $‰) are now
+supported [perl #69032]. They are also supported with C<our> and C<my>,
+but that is a mistake that will be fixed before 5.16.
+
+=head2 The Unicode C<Script_Extensions> property is now supported.
+
+New in Unicode 6.0, this is an improved C<Script> property. Details
+are in L<perlunicode/Scripts>.
+
+=head2 Lvalue Subroutines
+
+XXX
+
+=head2 XS Changes
+
+XXX
+
+=head2 Improved typemaps for Some Builtin Types
+
+Most XS authors will be aware that there is a longstanding bug in the
+OUTPUT typemap for T_AVREF (C<AV*>), T_HVREF (C<HV*>), T_CVREF (C<CV*>),
+and T_SVREF (C<SVREF> or C<\$foo>) that requires manually decrementing
+the reference count of the return value instead of the typemap taking
+care of this. For backwards-compatibility, this cannot be changed in the
+default typemaps. But we now provide additional typemaps
+C<T_AVREF_REFCOUNT_FIXED>, etc. that do not exhibit this bug. Using
+them in your extension is as simple as having one line in your
+C<TYPEMAP> section:
+
+ HV* T_HVREF_REFCOUNT_FIXED
+
+=head3 C<is_utf8_char()>
+
+The XS-callable function C<is_utf8_char()>, when presented with
+malformed UTF-8 input, can read up to 12 bytes beyond the end of the
+string. This cannot be fixed without changing its API. It is not
+called from CPAN. The documentation now describes how to use it
+safely.
+
+=head3 Other C<is_utf8_foo()> functions, as well as C<utf8_to_foo()>, etc.
+
+Most of the other XS-callable functions that take UTF-8 encoded input
+implicitly assume that the UTF-8 is valid (not malformed) in regards to
+buffer length. Do not do things such as change a character's case or
+see if it is alphanumeric without first being sure that it is valid
+UTF-8. This can be safely done for a whole string by using one of the
+functions C<is_utf8_string()>, C<is_utf8_string_loc()>, and
+C<is_utf8_string_loclen()>.
+
+=head2 Changes to Special Variables
+
+XXX
+
+=head2 Debugger Changes
+
+=head3 Features inside the debugger
+
+The current Perl's L<feature> bundle is now enabled for commands entered
+in the interactive debugger.
+
+=head3 New option for the debugger's B<t> command
+
+The B<t> command in the debugger, which toggles tracing mode, now
+accepts a numeric argument that determines how many levels of subroutine
+calls to trace.
+
+=head3 C<enable> and C<disable>
+
+The debugger now has C<disable> and C<enable> commands for disabling
+existing breakpoints and reënabling them. See L<perldebug>.
+
+=head3 Breakpoints with file names
+
+The debugger's "b" command for setting breakpoints now allows a line
+number to be prefixed with a file name. See
+L<perldebug/"b [file]:[line] [condition]">.
+
+=head2 The C<CORE> Namespace
+
+=for comment This needs to be rewritten for 5.16 -- rjbs, 2012-02-20
+
+The C<CORE::> prefix can now be used on keywords enabled by
+L<feature.pm|feature>, even outside the scope of C<use feature>. Relevant
+documentation files L<CORE>, L<feature>, L<perlfunc>, L<perlsub>, and
+L<perlsyn> have been updated.
+
+Perl 5.15.2 introduced subroutines in the CORE namespace. Most of them
+could only be called as barewords; i.e., they could be aliased at compile
+time and then inlined under new names.
+
+Almost all of these functions can now be called through references and via
+C<&foo()> syntax, bypassing the prototype. See L<CORE> for a list of the
+exceptions.
+
+=head2 Other Changes
+
+XXX
+
+=head1 Security
+
+=head2 C<File::Glob::bsd_glob()> memory error with GLOB_ALTDIRFUNC (CVE-2011-2728).
+
+Calling C<File::Glob::bsd_glob> with the unsupported flag
+GLOB_ALTDIRFUNC would cause an access violation / segfault. A Perl
+program that accepts a flags value from an external source could expose
+itself to denial of service or arbitrary code execution attacks. There
+are no known exploits in the wild. The problem has been corrected by
+explicitly disabling all unsupported flags and setting unused function
+pointers to null. Bug reported by Clément Lecigne.
+
+=head2 Privileges are now set correctly when assigning to C<$(>
+
+A hypothetical bug (probably non-exploitable in practice) due to the
+incorrect setting of the effective group ID while setting C<$(> has been
+fixed. The bug would only have affected systems that have C<setresgid()>
+but not C<setregid()>, but no such systems are known of.
+
+=head1 Deprecations
+
+=head2 Don't read the Unicode data base files in F<lib/unicore>
+
+It is now deprecated to directly read the Unicode data base files.
+These are stored in the F<lib/unicore> directory. Instead, you should
+use the new functions in L<Unicode::UCD>. These provide a stable API,
+and give complete information. (This API is, however, subject to change
+somewhat during the 5.15 development cycle, as we gain experience and
+get feedback from using it.)
+
+Perl may at some point in the future change or remove the files. The
+file most likely for applications to have used is
+F<lib/unicore/ToDigit.pl>. L<Unicode::UCD/prop_invmap()> can be used to
+get at its data instead.
+
+=head1 Future Deprecations
+
+This section serves as a notice of feature that are I<likely> to be
+L<deprecated|perlpolicy/deprecated> in the next release of perl
+(5.18.0). If your code depends on these features, you should contact
+the Perl 5 Porters via the L<mailing
+list|http://lists.perl.org/list/perl5-porters.html> or L<perlbug> to
+explain your use case and inform the deprecation process.
+
+=head2 Core Modules
+
+These modules may be marked as deprecated I<from the core>. This only
+means that they will no longer be installed by default with the core
+distribution, but will remain available on the CPAN.
+
+=over
+
+=item CPANPLUS
+
+=item Filter::Simple
+
+=item PerlIO::mmap
+
+=item Pod::Parser, Pod::LaTeX
+
+=item SelfLoader
+
+=item Text::Soundex
+
+=item Thread.pm
+
+=back
+
+=head2 Platforms with no supporting programmers:
+
+=over
+
+=item BeOS
+
+=item djgpp
+
+=item dgux
+
+=item EPOC
+
+=item MPE/iX
+
+=item Rhapsody
+
+=item UTS
+
+=item VM/ESA
+
+=back
+
+=head2 Other Future Deprecations
+
+=over
+
+=item Swapping of $< and $>
+
+https://rt.perl.org/rt3/Ticket/Display.html?id=96212
+
+=item sfio, stdio
+
+=back
+
+ XXX THIS HUNK IS XXX
+ XXX HERE TO REMIND RJBS XXX
+ XXX JUST HOW FAR HE EDITED XXX
+
+=head2 Anonymous handles
+
+Automatically generated file handles are now named __ANONIO__ when the
+variable name cannot be determined, rather than $__ANONIO__.
+
+=head2 Last-accessed filehandle
+
+Perl has an internal variable that stores the last filehandle to be
+accessed. It is used by C<$.> and by C<tell> and C<eof> without
+arguments.
-Various warnings and error messages that mention variable names or values,
-methods, etc.
+It used to be possible to set this internal variable to a glob copy and
+then modify that glob copy to be something other than a glob, and still
+have the last-accessed filehandle associated with the variable after
+assigning a glob to it again:
-=back
+ my $foo = *STDOUT; # $foo is a glob copy
+ <$foo>; # $foo is now the last-accessed handle
+ $foo = 3; # no longer a glob
+ $foo = *STDERR; # still the last-accessed handle
-In addition, a parsing bug has been fixed that prevented C<*{é}> from
-implicitly quoting the name, but instead interpreted it as C<*{+é}>, which
-would cause a strict violation.
+Now the C<$foo = 3> assignment unsets that internal variable, so there
+is no last-accessed filehandle, just as if C<< <$foo> >> had never
+happened.
-C<*{"*a::b"}> automatically strips off the * if it is followed by an ASCII
-letter. That has been extended to all Unicode identifier characters.
+=head2 $^X converted to an absolute path on FreeBSD, OS X and Solaris
-C<$é> is now subject to "Used only once" warnings. It used to be exempt,
-as it was treated as a punctuation variable.
+C<$^X> is now converted to an absolute path on OS X, FreeBSD (without
+needing F</proc> mounted) and Solaris 10 and 11. This augments the
+previous approach of using F</proc> on Linux, FreeBSD and NetBSD
+(in all cases, where mounted).
-Also, single-character Unicode punctuation variables (like $‰) are now
-supported [perl #69032]. They are also supported with C<our> and C<my>,
-but that is a mistake that will be fixed before 5.16.
+This makes relocatable perl installations more useful on these platforms.
+(See "Relocatable @INC" in F<INSTALL>)
=head2 Support for Embedded Nulls
sub AUTOLOAD { ... }
@sorted = sort foo @list; # uses AUTOLOAD
-=head2 Improved typemaps for Some Builtin Types
-
-Most XS authors will be aware that there is a longstanding bug
-in the OUTPUT typemap for T_AVREF (C<AV*>), T_HVREF (C<HV*>),
-T_CVREF (C<CV*>), and T_SVREF (C<SVREF> or C<\$foo>) that requires
-manually decrementing the reference count of the return value
-instead of the typemap taking care of this. For
-backwards-compatibility, this cannot be changed in the default
-typemaps. But we now provide additional typemaps
-C<T_AVREF_REFCOUNT_FIXED>, etc. that do not exhibit this bug.
-Using them in your extension is as simple as having one line
-in your C<TYPEMAP> section:
-
- HV* T_HVREF_REFCOUNT_FIXED
-
-=head1 Performance Enhancements
-
-=over 4
-
-=item *
-
-Version declarations with the C<use> keyword (e.g., C<use 5.012>) are now
-faster, as they enable features without loading F<feature.pm>.
-
-=item *
-
-C<local $_> is faster now, as it no longer iterates through magic that it
-is not going to copy anyway.
-
-=item *
-
-Perl 5.12.0 sped up the destruction of objects whose classes define
-empty C<DESTROY> methods (to prevent autoloading), by simply not
-calling such empty methods. This release takes this optimisation a
-step further, by not calling any C<DESTROY> method that begins with a
-C<return> statement. This can be useful for destructors that are only
-used for debugging:
-
- use constant DEBUG => 1;
- sub DESTROY { return unless DEBUG; ... }
-
-Constant-folding will reduce the first statement to C<return;> if DEBUG
-is set to 0, triggering this optimisation.
-
-=item *
-
-Assigning to a variable that holds a typeglob or copy-on-write scalar
-is now much faster. Previously the typeglob would be stringified or
-the copy-on-write scalar would be copied before being clobbered.
-
-=item *
-
-Assignment to C<substr> in void context is now more than twice its
-previous speed. Instead of creating and returning a special lvalue
-scalar that is then assigned to, C<substr> modifies the original string
-itself.
-
-
-=item *
-
-C<substr> no longer calculates a value to return when called in void
-context.
-
-=back
-
-=head2 C<CORE::> works on all keywords
-
-The C<CORE::> prefix can now be used on keywords enabled by
-L<feature.pm|feature>, even outside the scope of C<use feature>. Relevant
-documentation files L<CORE>, L<feature>, L<perlfunc>, L<perlsub>, and
-L<perlsyn> have been updated.
-
-Perl 5.15.2 introduced subroutines in the CORE namespace. Most of them
-could only be called as barewords; i.e., they could be aliased at compile
-time and then inlined under new names.
-
-Almost all of these functions can now be called through references and via
-C<&foo()> syntax, bypassing the prototype. See L<CORE> for a list of the
-exceptions.
-
=head2 C<continue> no longer requires the "switch" feature
The C<continue> keyword has two meanings. It can introduce a C<continue>
avoid conflicts with user-defined subroutines, there is no reason for
C<continue> to depend on it.
-=head2 New debugger commands
-
-The debugger now has C<disable> and C<enable> commands for disabling
-existing breakpoints and reënabling them. See L<perldebug>.
-
=head2 C<$$> can be assigned to
C<$$> was made read-only in Perl 5.8.0. But only sometimes: C<local $$>
read-only. (This change also allowed a bug to be fixed while maintaining
backward compatibility.)
-=head2 Features inside the debugger
-
-The current Perl's feature bundle is now enabled for commands entered in
-the interactive debugger.
-
=head2 C<\N{...}> can now have Unicode loose name matching
This is described in the C<charnames> item in
L</Updated Modules and Pragmata> below.
-=head2 Breakpoints with file names
-
-The debugger's "b" command for setting breakpoints now allows a line number
-to be prefixed with a file name. See
-L<perldebug/"b [file]:[line] [condition]">.
-
=head2 C<splice()> doesn't warn when truncating
You can now limit the size of an array using C<splice(@a,MAX_LEN)> without
arguments. This means that one can override the built-in functions with
custom subroutines that parse their arguments the same way.
-=head2 You can now C<study> more than one string
-
-The restriction that you can only have one C<study> active at a time has been
-removed. You can now usefully C<study> as many strings as you want (until you
-exhaust memory).
-
-=head2 The Unicode C<Script_Extensions> property is now supported.
-
-New in Unicode 6.0, this is an improved C<Script> property. Details
-are in L<perlunicode/Scripts>.
-
=head2 DTrace probes for interpreter phase change
The C<phase-change> probes will fire when the interpreter's phase
Many new functions have been added to the API for manipulating lexical
pads. See L<perlapi/Pad Data Structures> for more information.
-=head2 Subroutines in the CORE namespace
-
-Many Perl keywords are now available as subroutines in the CORE namespace.
-Most of these cannot be called through references or via C<&foo> syntax
-yet, but must be called as barewords. In other words, you can now do
-this:
-
- BEGIN { *entangle = \&CORE::tie }
- entangle $variable, $package, @args;
-
-This currently works for overridable keywords other than C<dump> and the
-infix operators. Calling through references only works for functions that
-take no arguments (like C<wantarray>).
-
-Work is under way to allow more of these subroutines to be called through
-references.
-
=head2 C<__FILE__()> Syntax
The C<__FILE__>, C<__LINE__> and C<__PACKAGE__> tokens can now be written
with an empty pair of parentheses after them. This makes them parse the
same way as C<time>, C<fork> and other built-in functions.
-=head1 Security
-
-=head2 Privileges are now set correctly when assigning to C<$(>
-
-A hypothetical bug (probably non-exploitable in practice) due to the
-incorrect setting of the effective group ID while setting C<$(> has been
-fixed. The bug would only have affected systems that have C<setresgid()>
-but not C<setregid()>, but no such systems are known of.
-
-=head2 C<File::Glob::bsd_glob()> memory error with GLOB_ALTDIRFUNC (CVE-2011-2728).
-
-Calling C<File::Glob::bsd_glob> with the unsupported flag
-GLOB_ALTDIRFUNC would cause an access violation / segfault. A Perl
-program that accepts a flags value from an external source could expose
-itself to denial of service or arbitrary code execution attacks. There
-are no known exploits in the wild. The problem has been corrected by
-explicitly disabling all unsupported flags and setting unused function
-pointers to null. Bug reported by Clément Lecigne.
-
=head1 Incompatible Changes
=head2 Certain deprecated Unicode properties are no longer supported by default
The solution was to make it stringify like a normal anonymous typeglob,
like those produced by C<< open($foo->{bar}, ...) >> [perl #96326].
-
=head2 User-defined case changing operations.
This feature was deprecated in Perl 5.14, and has now been removed.
L</Core Enhancements>, C<$$> is now writable, but it will be reset during a
fork.
-=head1 Deprecations
-
-=head2 Don't read the Unicode data base files in F<lib/unicore>
-
-It is now deprecated to directly read the Unicode data base files.
-These are stored in the F<lib/unicore> directory. Instead, you should
-use the new functions in L<Unicode::UCD>. These provide a stable API,
-and give complete information. (This API is, however, subject to change
-somewhat during the 5.15 development cycle, as we gain experience and
-get feedback from using it.)
-
-Perl may at some point in the future change or remove the files. The
-file most likely for applications to have used is F<lib/unicore/ToDigit.pl>.
-L<Unicode::UCD/prop_invmap()> can be used to get at its data instead.
-
-=head1 Future Deprecations
-
-This section serves as a notice of feature that are I<likely> to be
-L<deprecated|perlpolicy/deprecated> in the next release of perl (5.18.0). If
-your code depends on these features, you should contact the Perl 5 Porters via
-the L<mailing list|http://lists.perl.org/list/perl5-porters.html> or L<perlbug>
-to explain your use case and inform the deprecation process.
-
-=head2 Core Modules
-
-These modules may be marked as deprecated I<from the core>. This only means
-that they will no longer be installed by default with the core distribution,
-but will remain available on the CPAN.
+=head1 Performance Enhancements
=over
-=item CPANPLUS
-
-=item Filter::Simple
-
-=item PerlIO::mmap
-
-=item Pod::Parser, Pod::LaTeX
-
-=item SelfLoader
-
-=item Text::Soundex
-
-=item Thread.pm
+=item *
-=back
+Improved performance for Unicode properties in regular expressions
-=item Platforms with no supporting programmers:
+=for comment Can this be compacted some? -- rjbs, 2012-02-20
-=over
+Matching a code point against a Unicode property is now done via a
+binary search instead of linear. This means for example that the worst
+case for a 1000 item property is 10 probes instead of 1000. This
+inefficiency has been compensated for in the past by permanently storing
+in a hash the results of a given probe plus the results for the adjacent
+64 code points, under the theory that near-by code points are likely to
+be searched for. A separate hash was used for each mention of a Unicode
+property in each regular expression. Thus, C<qr/\p{foo}abc\p{foo}/>
+would generate two hashes. Any probes in one instance would be unknown
+to the other, and the hashes could expand separately to be quite large
+if the regular expression were used on many different widely-separated
+code points. This can lead to running out of memory in extreme cases.
+Now, however, there is just one hash shared by all instances of a given
+property. This means that if C<\p{foo}> is matched against "A" in one
+regular expression in a thread, the result will be known immediately to
+all regular expressions, and the relentless march of using up memory is
+slowed considerably.
-=item BeOS
+=item *
-=item djgpp
+Version declarations with the C<use> keyword (e.g., C<use 5.012>) are now
+faster, as they enable features without loading F<feature.pm>.
-=item dgux
+=item *
-=item EPOC
+C<local $_> is faster now, as it no longer iterates through magic that it
+is not going to copy anyway.
-=item MPE/iX
+=item *
-=item Rhapsody
+Perl 5.12.0 sped up the destruction of objects whose classes define
+empty C<DESTROY> methods (to prevent autoloading), by simply not
+calling such empty methods. This release takes this optimisation a
+step further, by not calling any C<DESTROY> method that begins with a
+C<return> statement. This can be useful for destructors that are only
+used for debugging:
-=item UTS
+ use constant DEBUG => 1;
+ sub DESTROY { return unless DEBUG; ... }
-=item VM/ESA
+Constant-folding will reduce the first statement to C<return;> if DEBUG
+is set to 0, triggering this optimisation.
-=back
+=item *
-=head2 Other Future Deprecations
+Assigning to a variable that holds a typeglob or copy-on-write scalar
+is now much faster. Previously the typeglob would be stringified or
+the copy-on-write scalar would be copied before being clobbered.
-=over
+=item *
-=item Swapping of $< and $>
+Assignment to C<substr> in void context is now more than twice its
+previous speed. Instead of creating and returning a special lvalue
+scalar that is then assigned to, C<substr> modifies the original string
+itself.
-https://rt.perl.org/rt3/Ticket/Display.html?id=96212
+=item *
-=item sfio, stdio
+C<substr> no longer calculates a value to return when called in void
+context.
=back
-=head1 Performance Enhancements
-
=over 4
=item *
-Due to changes in L<File::Glob>, Perl's C<glob> function and its
-C<< <...> >> equivalent are now much faster. The splitting of the pattern
-into words has been rewritten in C, resulting in speed-ups of 20% in some
-cases.
+Due to changes in L<File::Glob>, Perl's C<glob> function and its C<<
+<...> >> equivalent are now much faster. The splitting of the pattern
+into words has been rewritten in C, resulting in speed-ups of 20% in
+some cases.
This does not affect VMS, as it does not use File::Glob.
=head3 Old OO Documentation
All the old OO tutorials, perltoot, perltooc, and perlboot, have been
-removed. The perlbot (bag of object tricks) document has been removed as well.
+removed. The perlbot (bag of object tricks) document has been removed
+as well.
=head3 Development Deltas
including warnings and fatal error messages. For the complete list of
diagnostic messages, see L<perldiag>.
-XXX New or changed warnings emitted by the core's C<C> code go here. Also
-include any changes in L<perldiag> that reconcile it to the C<C> code.
-
-[ Within each section, list entries as a =item entry that links to perldiag,
- e.g.
-
- =item *
-
- L<Invalid version object|perldiag/"Invalid version object">
-]
-
=head2 New Diagnostics
-XXX Newly added diagnostic messages go here
-
=head3 New Errors
=over 4
=item *
-L<That use of $[ is unsupported|perldiag/"That use of $[ is unsupported">
-
-This previously removed error has been restored with the re-implementation
-of C<$[> as a module.
-
-=item *
-
L<&CORE::%s cannot be called directly|perldiag/"&CORE::%s cannot be called directly">
(F) You tried to call a subroutine in the C<CORE::> namespace
"sort is now a reserved word"
-This error used to occur when C<sort> was called without arguments, followed by C<;> or C<)>. (E.g., C<sort;> would die, but C<{sort}> was
+This error used to occur when C<sort> was called without arguments,
+followed by C<;> or C<)>. (E.g., C<sort;> would die, but C<{sort}> was
OK.) This error message was added in Perl 3 to catch code like
C<close(sort)> which would no longer work. More than two decades later,
this message is no longer appropriate. Now C<sort> without arguments is
-always allowed, and returns an empty list, as it did in those cases where
-it was already allowed [perl #90030].
+always allowed, and returns an empty list, as it did in those cases
+where it was already allowed [perl #90030].
=back
=item *
The error messages for using C<default> and C<when> outside of a
-topicalizer have been standardised to match the messages for
-C<continue> and loop controls. They now read 'Can't "default" outside
-a topicalizer' and 'Can't "when" outside a topicalizer'. They both
-used to be 'Can't use when() outside a topicalizer' [perl #91514].
-
+topicalizer have been standardised to match the messages for C<continue>
+and loop controls. They now read 'Can't "default" outside a
+topicalizer' and 'Can't "when" outside a topicalizer'. They both used
+to be 'Can't use when() outside a topicalizer' [perl #91514].
=item *
-The uninitialized warning for C<y///r> when C<$_> is implicit and undefined
-now mentions the variable name, just like the non-/r variation of the
-operator.
+The uninitialized warning for C<y///r> when C<$_> is implicit and
+undefined now mentions the variable name, just like the non-/r variation
+of the operator.
=item *
-The "Applying pattern match..." or similar warning produced when an array
-or hash is on the left-hand side of the C<=~> operator now mentions the
-name of the variable.
+The "Applying pattern match..." or similar warning produced when an
+array or hash is on the left-hand side of the C<=~> operator now
+mentions the name of the variable.
=item *
=item *
-The message,
-"Code point 0x%X is not Unicode, no properties match it; all inverse
-prop erties do" has been changed to "Code point 0x%X is not Unicode, all
-\p{} matches fail; all \P{} matches succeed"
+The message, "Code point 0x%X is not Unicode, no properties match it;
+all inverse prop erties do" has been changed to "Code point 0x%X is not
+Unicode, all \p{} matches fail; all \P{} matches succeed"
=item *
-Warnings that mention the names of lexical (C<my>) variables with Unicode
-characters in them now respect the presence or absence of the C<:utf8>
-layer on the output handle, instead of outputting UTF8 regardless. Also,
-the correct names are included in the strings passed to C<$SIG{__WARN__}>
-handlers, rather than the raw UTF8 bytes.
+Warnings that mention the names of lexical (C<my>) variables with
+Unicode characters in them now respect the presence or absence of the
+C<:utf8> layer on the output handle, instead of outputting UTF8
+regardless. Also, the correct names are included in the strings passed
+to C<$SIG{__WARN__}> handlers, rather than the raw UTF8 bytes.
=back
=item *
-splain no longer emits backtraces with the first line number repeated.
+F<splain> no longer emits backtraces with the first line number repeated.
+
This:
Uncaught exception from user code:
=item *
-The -Dusesitecustomize and -Duserelocatableinc options now work
+The C<-Dusesitecustomize> and C<-Duserelocatableinc> options now work
together properly.
=item *
https://perl5.git.perl.org / perl5.git / commitdiff