package feature;
-our $VERSION = '1.46';
+our $VERSION = '1.57';
our %feature = (
fc => 'feature_fc',
+ isa => 'feature_isa',
say => 'feature_say',
state => 'feature_state',
switch => 'feature_switch',
bitwise => 'feature_bitwise',
evalbytes => 'feature_evalbytes',
- array_base => 'feature_arybase',
signatures => 'feature_signatures',
current_sub => 'feature___SUB__',
refaliasing => 'feature_refaliasing',
);
our %feature_bundle = (
- "5.10" => [qw(array_base say state switch)],
- "5.11" => [qw(array_base say state switch unicode_strings)],
+ "5.10" => [qw(say state switch)],
+ "5.11" => [qw(say state switch unicode_strings)],
"5.15" => [qw(current_sub evalbytes fc say state switch unicode_eval unicode_strings)],
"5.23" => [qw(current_sub evalbytes fc postderef_qq say state switch unicode_eval unicode_strings)],
- "all" => [qw(array_base bitwise current_sub declared_refs evalbytes fc postderef_qq refaliasing say signatures state switch unicode_eval unicode_strings)],
- "default" => [qw(array_base)],
+ "5.27" => [qw(bitwise current_sub evalbytes fc postderef_qq say state switch unicode_eval unicode_strings)],
+ "all" => [qw(bitwise current_sub declared_refs evalbytes fc isa postderef_qq refaliasing say signatures state switch unicode_eval unicode_strings)],
+ "default" => [qw()],
);
$feature_bundle{"5.12"} = $feature_bundle{"5.11"};
$feature_bundle{"5.24"} = $feature_bundle{"5.23"};
$feature_bundle{"5.25"} = $feature_bundle{"5.23"};
$feature_bundle{"5.26"} = $feature_bundle{"5.23"};
+$feature_bundle{"5.28"} = $feature_bundle{"5.27"};
+$feature_bundle{"5.29"} = $feature_bundle{"5.27"};
+$feature_bundle{"5.30"} = $feature_bundle{"5.27"};
+$feature_bundle{"5.31"} = $feature_bundle{"5.27"};
+$feature_bundle{"5.32"} = $feature_bundle{"5.27"};
$feature_bundle{"5.9.5"} = $feature_bundle{"5.10"};
my %noops = (
postderef => 1,
lexical_subs => 1,
);
+my %removed = (
+ array_base => 1,
+);
our $hint_shift = 26;
our $hint_mask = 0x1c000000;
-our @hint_bundles = qw( default 5.10 5.11 5.15 5.23 );
+our @hint_bundles = qw( default 5.10 5.11 5.15 5.23 5.27 );
# This gets set (for now) in $^H as well as in %^H,
# for runtime speed of the uc/lc/ucfirst/lcfirst functions.
This feature is available starting with Perl 5.12; was almost fully
implemented in Perl 5.14; and extended in Perl 5.16 to cover C<quotemeta>;
-and extended further in Perl 5.26 to cover L<the range
-operator|perlop/Range Operators>.
+was extended further in Perl 5.26 to cover L<the range
+operator|perlop/Range Operators>; and was extended again in Perl 5.28 to
+cover L<special-cased whitespace splitting|perlfunc/split>.
=head2 The 'unicode_eval' and 'evalbytes' features
-Under the C<unicode_eval> feature, Perl's C<eval> function, when passed a
-string, will evaluate it as a string of characters, ignoring any
-C<use utf8> declarations. C<use utf8> exists to declare the encoding of
-the script, which only makes sense for a stream of bytes, not a string of
-characters. Source filters are forbidden, as they also really only make
-sense on strings of bytes. Any attempt to activate a source filter will
-result in an error.
-
-The C<evalbytes> feature enables the C<evalbytes> keyword, which evaluates
-the argument passed to it as a string of bytes. It dies if the string
-contains any characters outside the 8-bit range. Source filters work
-within C<evalbytes>: they apply to the contents of the string being
-evaluated.
-
-Together, these two features are intended to replace the historical C<eval>
-function, which has (at least) two bugs in it, that cannot easily be fixed
-without breaking existing programs:
-
-=over
-
-=item *
-
-C<eval> behaves differently depending on the internal encoding of the
-string, sometimes treating its argument as a string of bytes, and sometimes
-as a string of characters.
-
-=item *
+Together, these two features are intended to replace the legacy string
+C<eval> function, which behaves problematically in some instances. They are
+available starting with Perl 5.16, and are enabled by default by a
+S<C<use 5.16>> or higher declaration.
-Source filters activated within C<eval> leak out into whichever I<file>
-scope is currently being compiled. To give an example with the CPAN module
-L<Semi::Semicolons>:
+C<unicode_eval> changes the behavior of plain string C<eval> to work more
+consistently, especially in the Unicode world. Certain (mis)behaviors
+couldn't be changed without breaking some things that had come to rely on
+them, so the feature can be enabled and disabled. Details are at
+L<perlfunc/Under the "unicode_eval" feature>.
- BEGIN { eval "use Semi::Semicolons; # not filtered here " }
- # filtered here!
-
-C<evalbytes> fixes that to work the way one would expect:
-
- use feature "evalbytes";
- BEGIN { evalbytes "use Semi::Semicolons; # filtered " }
- # not filtered
-
-=back
-
-These two features are available starting with Perl 5.16.
+C<evalbytes> is like string C<eval>, but operating on a byte stream that is
+not UTF-8 encoded. Details are at L<perlfunc/evalbytes EXPR>. Without a
+S<C<use feature 'evalbytes'>> nor a S<C<use v5.16>> (or higher) declaration in
+the current scope, you can still access it by instead writing
+C<CORE::evalbytes>.
=head2 The 'current_sub' feature
=head2 The 'array_base' feature
-This feature supports the legacy C<$[> variable. See L<perlvar/$[> and
-L<arybase>. It is on by default but disabled under C<use v5.16> (see
-L</IMPLICIT LOADING>, below).
+This feature supported the legacy C<$[> variable. See L<perlvar/$[>.
+It was on by default but disabled under C<use v5.16> (see
+L</IMPLICIT LOADING>, below) and unavailable since perl 5.30.
This feature is available under this name starting with Perl 5.16. In
previous versions, it was simply on all the time, and this pragma knew
=head2 The 'bitwise' feature
-B<WARNING>: This feature is still experimental and the implementation may
-change in future versions of Perl. For this reason, Perl will
-warn when you use the feature, unless you have explicitly disabled the
-warning:
-
- no warnings "experimental::bitwise";
-
This makes the four standard bitwise operators (C<& | ^ ~>) treat their
operands consistently as numbers, and introduces four new dotted operators
(C<&. |. ^. ~.>) that treat their operands consistently as strings. The
See L<perlop/Bitwise String Operators> for details.
-This feature is available from Perl 5.22 onwards.
+This feature is available from Perl 5.22 onwards. Starting in Perl 5.28,
+C<use v5.28> will enable the feature. Before 5.28, it was still
+experimental and would emit a warning in the "experimental::bitwise"
+category.
=head2 The 'declared_refs' feature
This feature is available from Perl 5.26 onwards.
+=head2 The 'isa' feature
+
+This allows the use of the C<isa> infix operator, which tests whether the
+scalar given by the left operand is an object of the class given by the
+right operand. See L<perlop/Class Instance Operator> for more details.
+
+This feature is available from Perl 5.32 onwards.
+
=head1 FEATURE BUNDLES
It's possible to load multiple features together, using
bundle features included
--------- -----------------
- :default array_base
+ :default
- :5.10 say state switch array_base
+ :5.10 say state switch
- :5.12 say state switch unicode_strings array_base
+ :5.12 say state switch unicode_strings
- :5.14 say state switch unicode_strings array_base
+ :5.14 say state switch unicode_strings
:5.16 say state switch unicode_strings
unicode_eval evalbytes current_sub fc
unicode_eval evalbytes current_sub fc
postderef_qq
+ :5.28 say state switch unicode_strings
+ unicode_eval evalbytes current_sub fc
+ postderef_qq bitwise
+
+ :5.30 say state switch unicode_strings
+ unicode_eval evalbytes current_sub fc
+ postderef_qq bitwise
+
+ :5.32 say state switch unicode_strings
+ unicode_eval evalbytes current_sub fc
+ postderef_qq bitwise
+
The C<:default> bundle represents the feature set that is enabled before
any C<use feature> or C<no feature> declaration.
If the required version is older than Perl 5.10, the ":default" feature
bundle is automatically loaded instead.
+Unlike C<use feature ":5.12">, saying C<use v5.12> (or any higher version)
+also does the equivalent of C<use strict>; see L<perlfunc/use> for details.
+
=back
=cut
my $import = shift;
my $bundle_number = $^H & $hint_mask;
my $features = $bundle_number != $hint_mask
- && $feature_bundle{$hint_bundles[$bundle_number >> $hint_shift]};
+ && $feature_bundle{$hint_bundles[$bundle_number >> $hint_shift]};
if ($features) {
# Features are enabled implicitly via bundle hints.
# Delete any keys that may be left over from last time.
if (exists $noops{$name}) {
next;
}
+ if (!$import && exists $removed{$name}) {
+ next;
+ }
unknown_feature($name);
}
if ($import) {
https://perl5.git.perl.org / perl5.git / blobdiff