Skip some File::Copy tests on Win32 since file permissions do not

[perl5.git] / lib / feature.pm

diff --git a/lib/feature.pm b/lib/feature.pm
index 39eaf8e..915b5c7 100644 (file)
--- a/lib/feature.pm
+++ b/lib/feature.pm
@@ -1,21 +1,23 @@
 package feature;
 
-our $VERSION = '1.01';
+our $VERSION = '1.13';
 
 # (feature name) => (internal name, used in %^H)
 my %feature = (
     switch => 'feature_switch',
-    "~~"   => "feature_~~",
     say    => "feature_say",
-    err    => "feature_err",
-    dor    => "feature_err",
     state  => "feature_state",
 );
 
+# NB. the latest bundle must be loaded by the -E switch (see toke.c)
+
 my %feature_bundle = (
-    "5.10" => [qw(switch ~~ say err state)],
+    "5.10" => [qw(switch say state)],
+    "5.11" => [qw(switch say state)],
 );
 
+# special case
+$feature_bundle{"5.9.5"} = $feature_bundle{"5.10"};
 
 # TODO:
 # - think about versioned features (use feature switch => 2)
@@ -35,6 +37,8 @@ feature - Perl pragma to enable new syntactic features
        default           { say "None of the above" }
     }
 
+    use feature ':5.10'; # loads all features available in perl 5.10
+
 =head1 DESCRIPTION
 
 It is usually impossible to add new syntax to Perl without breaking
@@ -46,7 +50,7 @@ scope.
 =head2 Lexical effect
 
 Like other pragmas (C<use strict>, for example), features have a lexical
-effect.  C<use feature qw(foo)> will only make the feature "foo" available
+effect. C<use feature qw(foo)> will only make the feature "foo" available
 from that point to the end of the enclosing block.
 
     {
@@ -55,6 +59,21 @@ from that point to the end of the enclosing block.
     }
     print "But not here.\n";
 
+=head2 C<no feature>
+
+Features can also be turned off by using C<no feature "foo">. This too
+has lexical effect.
+
+    use feature 'say';
+    say "say is available here";
+    {
+        no feature 'say';
+        print "But not here.\n";
+    }
+    say "Yet it is here.";
+
+C<no feature> with no features specified will turn off all features.
+
 =head2 The 'switch' feature
 
 C<use feature 'switch'> tells the compiler to enable the Perl 6
@@ -62,13 +81,6 @@ given/when construct.
 
 See L<perlsyn/"Switch statements"> for details.
 
-=head2 The '~~' feature
-
-C<use feature '~~'> tells the compiler to enable the Perl 6
-smart match C<~~> operator.
-
-See L<perlsyn/"Smart Matching in Detail"> for details.
-
 =head2 The 'say' feature
 
 C<use feature 'say'> tells the compiler to enable the Perl 6
@@ -76,18 +88,6 @@ C<say> function.
 
 See L<perlfunc/say> for details.
 
-=head2 the 'err' feature
-
-C<use feature 'err'> tells the compiler to enable the C<err>
-operator.
-
-C<err> is a low-precedence variant of the C<//> operator:
-see C<perlop> for details.
-
-=head2 the 'dor' feature
-
-The 'dor' feature is an alias for the 'err' feature.
-
 =head2 the 'state' feature
 
 C<use feature 'state'> tells the compiler to enable C<state>
@@ -100,8 +100,45 @@ See L<perlsub/"Persistent Private Variables"> for details.
 It's possible to load a whole slew of features in one go, using
 a I<feature bundle>. The name of a feature bundle is prefixed with
 a colon, to distinguish it from an actual feature. At present, the
-only feature bundle is C<use feature ":5.10">, which is equivalent
-to C<use feature qw(switch ~~ say err state)>.
+only feature bundle is C<use feature ":5.10"> which is equivalent
+to C<use feature qw(switch say state)>.
+
+Specifying sub-versions such as the C<0> in C<5.10.0> in feature bundles has
+no effect: feature bundles are guaranteed to be the same for all sub-versions.
+
+=head1 IMPLICIT LOADING
+
+There are two ways to load the C<feature> pragma implicitly :
+
+=over 4
+
+=item *
+
+By using the C<-E> switch on the command-line instead of C<-e>. It enables
+all available features in the main compilation unit (that is, the one-liner.)
+
+=item *
+
+By requiring explicitly a minimal Perl version number for your program, with
+the C<use VERSION> construct, and when the version is higher than or equal to
+5.10.0. That is,
+
+    use 5.10.0;
+
+will do an implicit
+
+    use feature ':5.10';
+
+and so on. Note how the trailing sub-version is automatically stripped from the
+version.
+
+But to avoid portability warnings (see L<perlfunc/use>), you may prefer:
+
+    use 5.010;
+
+with the same effect.
+
+=back
 
 =cut
 
@@ -112,11 +149,15 @@ sub import {
     }
     while (@_) {
        my $name = shift(@_);
-       if ($name =~ /^:(.*)/) {
-           if (!exists $feature_bundle{$1}) {
-               unknown_feature_bundle($1);
+       if (substr($name, 0, 1) eq ":") {
+           my $v = substr($name, 1);
+           if (!exists $feature_bundle{$v}) {
+               $v =~ s/^([0-9]+)\.([0-9]+).[0-9]+$/$1.$2/;
+               if (!exists $feature_bundle{$v}) {
+                   unknown_feature_bundle(substr($name, 1));
+               }
            }
-           unshift @_, @{$feature_bundle{$1}};
+           unshift @_, @{$feature_bundle{$v}};
            next;
        }
        if (!exists $feature{$name}) {
@@ -137,11 +178,15 @@ sub unimport {
 
     while (@_) {
        my $name = shift;
-       if ($name =~ /^:(.*)/) {
-           if (!exists $feature_bundle{$1}) {
-               unknown_feature_bundle($1);
+       if (substr($name, 0, 1) eq ":") {
+           my $v = substr($name, 1);
+           if (!exists $feature_bundle{$v}) {
+               $v =~ s/^([0-9]+)\.([0-9]+).[0-9]+$/$1.$2/;
+               if (!exists $feature_bundle{$v}) {
+                   unknown_feature_bundle(substr($name, 1));
+               }
            }
-           unshift @_, @{$feature_bundle{$1}};
+           unshift @_, @{$feature_bundle{$v}};
            next;
        }
        if (!exists($feature{$name})) {