Create a default-on 'format_vars' feature

Perl · May 4, 2021 · 7f31b17 · 7f31b17
1 parent acd998d
commit 7f31b17
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Showing 3 changed files with 92 additions and 51 deletions.
diff --git a/feature.h b/feature.h
@@ -18,18 +18,19 @@
 #define FEATURE_MYREF_BIT                0x0008
 #define FEATURE_EVALBYTES_BIT            0x0010
 #define FEATURE_FC_BIT                   0x0020
-#define FEATURE_INDIRECT_BIT             0x0040
-#define FEATURE_ISA_BIT                  0x0080
-#define FEATURE_MULTIDIMENSIONAL_BIT     0x0100
-#define FEATURE_POSTDEREF_QQ_BIT         0x0200
-#define FEATURE_REFALIASING_BIT          0x0400
-#define FEATURE_SAY_BIT                  0x0800
-#define FEATURE_SIGNATURES_BIT           0x1000
-#define FEATURE_STATE_BIT                0x2000
-#define FEATURE_SWITCH_BIT               0x4000
-#define FEATURE_TRY_BIT                  0x8000
-#define FEATURE_UNIEVAL_BIT              0x10000
-#define FEATURE_UNICODE_BIT              0x20000
+#define FEATURE_FORMAT_VARS_BIT          0x0040
+#define FEATURE_INDIRECT_BIT             0x0080
+#define FEATURE_ISA_BIT                  0x0100
+#define FEATURE_MULTIDIMENSIONAL_BIT     0x0200
+#define FEATURE_POSTDEREF_QQ_BIT         0x0400
+#define FEATURE_REFALIASING_BIT          0x0800
+#define FEATURE_SAY_BIT                  0x1000
+#define FEATURE_SIGNATURES_BIT           0x2000
+#define FEATURE_STATE_BIT                0x4000
+#define FEATURE_SWITCH_BIT               0x8000
+#define FEATURE_TRY_BIT                  0x10000
+#define FEATURE_UNIEVAL_BIT              0x20000
+#define FEATURE_UNICODE_BIT              0x40000
 
 #define FEATURE_BUNDLE_DEFAULT	0
 #define FEATURE_BUNDLE_510	1
@@ -131,6 +132,13 @@
 	 FEATURE_IS_ENABLED_MASK(FEATURE___SUB___BIT)) \
     )
 
+#define FEATURE_FORMAT_VARS_IS_ENABLED \
+    ( \
+	CURRENT_FEATURE_BUNDLE <= FEATURE_BUNDLE_527 \
+     || (CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
+	 FEATURE_IS_ENABLED_MASK(FEATURE_FORMAT_VARS_BIT)) \
+    )
+
 #define FEATURE_REFALIASING_IS_ENABLED \
     ( \
 	CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \
@@ -277,6 +285,11 @@ S_magic_sethint_feature(pTHX_ SV *keysv, const char *keypv, STRLEN keylen,
                 mask = FEATURE_FC_BIT;
                 break;
             }
+            else if (keylen == sizeof("feature_format_vars")-1
+                 && memcmp(subf+1, "ormat_vars", keylen - sizeof("feature_")) == 0) {
+                mask = FEATURE_FORMAT_VARS_BIT;
+                break;
+            }
             return;
 
         case 'i':

diff --git a/lib/feature.pm b/lib/feature.pm
@@ -5,7 +5,7 @@
 
 package feature;
 
-our $VERSION = '1.64';
+our $VERSION = '1.65';
 
 our %feature = (
     fc                   => 'feature_fc',
@@ -19,6 +19,7 @@ our %feature = (
     evalbytes            => 'feature_evalbytes',
     signatures           => 'feature_signatures',
     current_sub          => 'feature___SUB__',
+    format_vars          => 'feature_format_vars',
     refaliasing          => 'feature_refaliasing',
     postderef_qq         => 'feature_postderef_qq',
     unicode_eval         => 'feature_unieval',
@@ -29,13 +30,13 @@ our %feature = (
 );
 
 our %feature_bundle = (
-    "5.10"    => [qw(bareword_filehandles indirect multidimensional say state switch)],
-    "5.11"    => [qw(bareword_filehandles indirect multidimensional say state switch unicode_strings)],
-    "5.15"    => [qw(bareword_filehandles current_sub evalbytes fc indirect multidimensional say state switch unicode_eval unicode_strings)],
-    "5.23"    => [qw(bareword_filehandles current_sub evalbytes fc indirect multidimensional postderef_qq say state switch unicode_eval unicode_strings)],
-    "5.27"    => [qw(bareword_filehandles bitwise current_sub evalbytes fc indirect multidimensional postderef_qq say state switch unicode_eval unicode_strings)],
-    "all"     => [qw(bareword_filehandles bitwise current_sub declared_refs evalbytes fc indirect isa multidimensional postderef_qq refaliasing say signatures state switch try unicode_eval unicode_strings)],
-    "default" => [qw(bareword_filehandles indirect multidimensional)],
+    "5.10"    => [qw(bareword_filehandles format_vars indirect multidimensional say state switch)],
+    "5.11"    => [qw(bareword_filehandles format_vars indirect multidimensional say state switch unicode_strings)],
+    "5.15"    => [qw(bareword_filehandles current_sub evalbytes fc format_vars indirect multidimensional say state switch unicode_eval unicode_strings)],
+    "5.23"    => [qw(bareword_filehandles current_sub evalbytes fc format_vars indirect multidimensional postderef_qq say state switch unicode_eval unicode_strings)],
+    "5.27"    => [qw(bareword_filehandles bitwise current_sub evalbytes fc format_vars indirect multidimensional postderef_qq say state switch unicode_eval unicode_strings)],
+    "all"     => [qw(bareword_filehandles bitwise current_sub declared_refs evalbytes fc format_vars indirect isa multidimensional postderef_qq refaliasing say signatures state switch try unicode_eval unicode_strings)],
+    "default" => [qw(bareword_filehandles format_vars indirect multidimensional)],
 );
 
 $feature_bundle{"5.12"} = $feature_bundle{"5.11"};
@@ -429,6 +430,19 @@ C<try> are caught by executing the body of the C<catch> block.
 
 For more information, see L<perlsyn/"Try Catch Exception Handling">.
 
+=head2 The 'format_vars' feature.
+
+This feature enables the punctuation variables that affect the operation of
+formats. It is enabled by default, but can be turned off to disallow the use
+of these variables.
+
+  $^A  $^L  $%  $-  $:  $=  $^  $~
+
+This is provided for the possible future expansion of the language, which may
+wish to use variable syntax including these characters, but currently cannot
+due to its collision with these little-used variables. By disabling this
+feature it permits these as a possible future expansion.
+
 =head1 FEATURE BUNDLES
 
 It's possible to load multiple features together, using
@@ -442,64 +456,64 @@ The following feature bundles are available:
   bundle    features included
   --------- -----------------
   :default  indirect multidimensional
-            bareword_filehandles
+            bareword_filehandles format_vars
 
-  :5.10     bareword_filehandles indirect
+  :5.10     bareword_filehandles format_vars indirect
             multidimensional say state switch
 
-  :5.12     bareword_filehandles indirect
+  :5.12     bareword_filehandles format_vars indirect
             multidimensional say state switch
             unicode_strings
 
-  :5.14     bareword_filehandles indirect
+  :5.14     bareword_filehandles format_vars indirect
             multidimensional say state switch
             unicode_strings
 
   :5.16     bareword_filehandles current_sub evalbytes
-            fc indirect multidimensional say state
-            switch unicode_eval unicode_strings
+            fc format_vars indirect multidimensional say
+            state switch unicode_eval unicode_strings
 
   :5.18     bareword_filehandles current_sub evalbytes
-            fc indirect multidimensional say state
-            switch unicode_eval unicode_strings
+            fc format_vars indirect multidimensional say
+            state switch unicode_eval unicode_strings
 
   :5.20     bareword_filehandles current_sub evalbytes
-            fc indirect multidimensional say state
-            switch unicode_eval unicode_strings
+            fc format_vars indirect multidimensional say
+            state switch unicode_eval unicode_strings
 
   :5.22     bareword_filehandles current_sub evalbytes
-            fc indirect multidimensional say state
-            switch unicode_eval unicode_strings
+            fc format_vars indirect multidimensional say
+            state switch unicode_eval unicode_strings
 
   :5.24     bareword_filehandles current_sub evalbytes
-            fc indirect multidimensional postderef_qq
-            say state switch unicode_eval
+            fc format_vars indirect multidimensional
+            postderef_qq say state switch unicode_eval
             unicode_strings
 
   :5.26     bareword_filehandles current_sub evalbytes
-            fc indirect multidimensional postderef_qq
-            say state switch unicode_eval
+            fc format_vars indirect multidimensional
+            postderef_qq say state switch unicode_eval
             unicode_strings
 
   :5.28     bareword_filehandles bitwise current_sub
-            evalbytes fc indirect multidimensional
-            postderef_qq say state switch unicode_eval
-            unicode_strings
+            evalbytes fc format_vars indirect
+            multidimensional postderef_qq say state
+            switch unicode_eval unicode_strings
 
   :5.30     bareword_filehandles bitwise current_sub
-            evalbytes fc indirect multidimensional
-            postderef_qq say state switch unicode_eval
-            unicode_strings
+            evalbytes fc format_vars indirect
+            multidimensional postderef_qq say state
+            switch unicode_eval unicode_strings
 
   :5.32     bareword_filehandles bitwise current_sub
-            evalbytes fc indirect multidimensional
-            postderef_qq say state switch unicode_eval
-            unicode_strings
+            evalbytes fc format_vars indirect
+            multidimensional postderef_qq say state
+            switch unicode_eval unicode_strings
 
   :5.34     bareword_filehandles bitwise current_sub
-            evalbytes fc indirect multidimensional
-            postderef_qq say state switch unicode_eval
-            unicode_strings
+            evalbytes fc format_vars indirect
+            multidimensional postderef_qq say state
+            switch unicode_eval unicode_strings
 
 The C<:default> bundle represents the feature set that is enabled before
 any C<use feature> or C<no feature> declaration.

diff --git a/regen/feature.pl b/regen/feature.pl
@@ -41,6 +41,7 @@ BEGIN
     multidimensional => 'multidimensional',
     bareword_filehandles => 'bareword_filehandles',
     try             => 'try',
+    format_vars     => 'format_vars',
 );
 
 # NOTE: If a feature is ever enabled in a non-contiguous range of Perl
@@ -50,15 +51,15 @@ BEGIN
 # 5.odd implies the next 5.even, but an explicit 5.even can override it.
 
 # features bundles
-use constant V5_9_5 => sort qw{say state switch indirect multidimensional bareword_filehandles};
+use constant V5_9_5 => sort qw{say state switch indirect multidimensional bareword_filehandles format_vars};
 use constant V5_11  => sort ( +V5_9_5, qw{unicode_strings} );
 use constant V5_15  => sort ( +V5_11, qw{unicode_eval evalbytes current_sub fc} );
 use constant V5_23  => sort ( +V5_15, qw{postderef_qq} );
 use constant V5_27  => sort ( +V5_23, qw{bitwise} );
 
 my %feature_bundle = (
     all     => [ sort keys %feature ],
-    default => [ qw{indirect multidimensional bareword_filehandles} ],
+    default => [ qw{indirect multidimensional bareword_filehandles format_vars} ],
     # using 5.9.5 features bundle
     "5.9.5" => [ +V5_9_5 ],
     "5.10"  => [ +V5_9_5 ],
@@ -478,7 +479,7 @@ sub longest {
 __END__
 package feature;
 
-our $VERSION = '1.64';
+our $VERSION = '1.65';
 
 FEATURES
 
@@ -835,6 +836,19 @@ =head2 The 'try' feature.
 
 For more information, see L<perlsyn/"Try Catch Exception Handling">.
 
+=head2 The 'format_vars' feature.
+
+This feature enables the punctuation variables that affect the operation of
+formats. It is enabled by default, but can be turned off to disallow the use
+of these variables.
+
+  $^A  $^L  $%  $-  $:  $=  $^  $~
+
+This is provided for the possible future expansion of the language, which may
+wish to use variable syntax including these characters, but currently cannot
+due to its collision with these little-used variables. By disabling this
+feature it permits these as a possible future expansion.
+
 =head1 FEATURE BUNDLES
 
 It's possible to load multiple features together, using